Introduction Population growth and the excessive use of natural resources have caused significant changes in natural ecosystems, including a decrease in rainfall and an increase in temperature. The potential exists for them to decrease... more
Introduction
Population growth and the excessive use of natural resources have caused significant changes in natural ecosystems, including a decrease in rainfall and an increase in temperature. The potential exists for them to decrease vegetation and increase barren areas. Serious economic, social, and environmental damage can occur in natural ecosystems due to the destruction of land cover and other damages, such as dust storms. Therefore, ecosystem changes are taking place worldwide, both at the temporal and spatial scale, due to human activities and natural factors. So, investigating the amount of land use/cover changes, their effect on dust storms, and predicting these changes for the coming years can be an important step in reducing and controlling unprincipled changes, planning, and optimizing resource. Climate change and human activities, such as drought, human activities, and non-compliance with water rights, have a significant impact on the Hamon wetland area, so that the dry bed of the wetland has become the main sources of dust. This research is focused on investigating the impact of land use changes on dust storms and forecasting land use changes in the Sistan region for the next 20 years.
Material and Methods
The impact of land use changes on dust storms in the Sistan region was examined using Markov chain forecasting methods. For this purpose, first of all, the land use maps of 2002, 2011 and 2022 were prepared using satellite images. An anomalous method was used to investigate climatic parameters, including temperature, rainfall, and the number of days with dust, in the next step. To evaluate climatic changes, it is necessary to use a method that shows long-term changes. The anomaly method was employed for this purpose. The values of this index can be
either positiveor negative. In order to predict land use changes for the next 20 years, the combination of the maps of 2002 and 2022 for severe drought conditions were used by using Markov chain and Cell models. The Markov model was predicted to generate multiple images. The transfer probability matrix allows for the expression of the probability that any type of land cover will be found in any location in the future. Despite the accuracy of transmission probabilities for each user is unknown, due to the lack of information on the spatial distribution of users, the Markov model does not have any spatial dependence information. In contrast, to the automatic network, it is an agent that has the ability to change its state based on the application of the law that shows the new state in accordance with the previous state and the state of its neighbors.
Results and Discussion
This study examined the impact of land use change on dust in the Sistan region. At first, climatic changes of temperature, rainfall and number of dusty days were investigated and the results showed that the temperature has increased and rainfall has decreased in the Sistan region during the last two decades. The land use maps also showed that in the years when the Hamon wetland has been drained, pastures and dense vegetation have increased and barren lands and salt marshes have decreased. But due to the recent droughts like the year 2022, when a drought has occurred in the region, the use of vegetation and pasture has decreased and barren and salt marshes have increased. These conditions cause an increase in the level of dust in the region. The land use map for severe drought conditions in the next 20 years was predicted using the Markov model. It showed that in the future, pastures and dense vegetation will decrease, but barren lands and salt marsh areas will increase dramatically. As desertification and wind erosion increase, dust storms will also increase as a result of these conditions. The economic, social, environmental, and health conditions of residents in the region are adversely affected by dust storms. Therefore, proper planning and management can reduce the damages caused by dust storms in the Sistan region.
Population growth and the excessive use of natural resources have caused significant changes in natural ecosystems, including a decrease in rainfall and an increase in temperature. The potential exists for them to decrease vegetation and increase barren areas. Serious economic, social, and environmental damage can occur in natural ecosystems due to the destruction of land cover and other damages, such as dust storms. Therefore, ecosystem changes are taking place worldwide, both at the temporal and spatial scale, due to human activities and natural factors. So, investigating the amount of land use/cover changes, their effect on dust storms, and predicting these changes for the coming years can be an important step in reducing and controlling unprincipled changes, planning, and optimizing resource. Climate change and human activities, such as drought, human activities, and non-compliance with water rights, have a significant impact on the Hamon wetland area, so that the dry bed of the wetland has become the main sources of dust. This research is focused on investigating the impact of land use changes on dust storms and forecasting land use changes in the Sistan region for the next 20 years.
Material and Methods
The impact of land use changes on dust storms in the Sistan region was examined using Markov chain forecasting methods. For this purpose, first of all, the land use maps of 2002, 2011 and 2022 were prepared using satellite images. An anomalous method was used to investigate climatic parameters, including temperature, rainfall, and the number of days with dust, in the next step. To evaluate climatic changes, it is necessary to use a method that shows long-term changes. The anomaly method was employed for this purpose. The values of this index can be
either positiveor negative. In order to predict land use changes for the next 20 years, the combination of the maps of 2002 and 2022 for severe drought conditions were used by using Markov chain and Cell models. The Markov model was predicted to generate multiple images. The transfer probability matrix allows for the expression of the probability that any type of land cover will be found in any location in the future. Despite the accuracy of transmission probabilities for each user is unknown, due to the lack of information on the spatial distribution of users, the Markov model does not have any spatial dependence information. In contrast, to the automatic network, it is an agent that has the ability to change its state based on the application of the law that shows the new state in accordance with the previous state and the state of its neighbors.
Results and Discussion
This study examined the impact of land use change on dust in the Sistan region. At first, climatic changes of temperature, rainfall and number of dusty days were investigated and the results showed that the temperature has increased and rainfall has decreased in the Sistan region during the last two decades. The land use maps also showed that in the years when the Hamon wetland has been drained, pastures and dense vegetation have increased and barren lands and salt marshes have decreased. But due to the recent droughts like the year 2022, when a drought has occurred in the region, the use of vegetation and pasture has decreased and barren and salt marshes have increased. These conditions cause an increase in the level of dust in the region. The land use map for severe drought conditions in the next 20 years was predicted using the Markov model. It showed that in the future, pastures and dense vegetation will decrease, but barren lands and salt marsh areas will increase dramatically. As desertification and wind erosion increase, dust storms will also increase as a result of these conditions. The economic, social, environmental, and health conditions of residents in the region are adversely affected by dust storms. Therefore, proper planning and management can reduce the damages caused by dust storms in the Sistan region.
Introduction The temperature of the earth has been rising by about 0.74 degrees Celsius over the past century. A gradual increase in the average annual temperature has been reported by many researchers worldwide, while other reports... more
Introduction
The temperature of the earth has been rising by about 0.74 degrees Celsius over the past century. A gradual increase in the average annual temperature has been reported by many researchers worldwide, while other reports suggest a decrease in this parameter. The assumption is that there will be more areas of the world experiencing higher temperatures. The climate changes are effectively represented by temperature changes, which is considered one of the main indicators in climate studies. The chemical composition of the atmosphere has changed because of the increase in human industrial activities, so it is responsible for unprecedented changes in the global climate in the past century. The increase in greenhouse gas concentration is the cause of this change. The evidence indicates that the increase in atmospheric gas concentration has caused a significant increase in global temperature. The use of thermal data from sensors is widely used in the study of terrestrial phenomena, as indicated by many studies. The temperature of the earth's surface is directly and indirectly linked to all human activities. It is still not possible to calculate the temperature of the earth's surface with perfect and accurate methods, but some sensors with suitable temporal, spectral, and spatial performance are able to take photos of the entire surface of the Earth. The study is more important due to the fact that various species of animals, such as Jebeer (belonging to the Bovidae), are exposed to climate changes in arid and desert areas. Due to its impact on humans, other creatures, and the entire environment, it is imperative to pay attention to climate change nowadays. In this regard, the main aim of the current study is to evaluate the LST (Land Surface Temperature) trends, changes, and temperature threats of the land surface in the Central Plateau of Iran. Time series remote sensing data of the MODIS (MOD11A2) sensor and Terra satellite, in 8 days with spatial resolution of 1km from 2002 to 2018 have been used.
Material and Methods
The current study has been focused on the central plateau of Iran. The central plateau of Iran lies within the arid lands belt of the northern hemisphere. The current study has been attempting to extract exact information from the images by employing specific techniques. To achieve this goal, the MOD11A2 product of Terra satellite MODIS sensor, the trend of temperature changes and time series construction of the significance of Man Kendall methods and linear correlation parameters such as maximum monthly temperature, maximum annually temperature based on maximum monthly temperature, median monthly temperature, maximum annually temperature based on median monthly temperature, minimum monthly temperature, minimum annually temperature for daily and nightly temperature were used in TerrSet software and Earth Trends Modeler section to extract significant increasing and decreasing areas. After identifying some parts of provinces with significant temperatures based on analysis and results, we can identify the vital numerical value of the temperature in each pixel of those significant parts in the next stage. This can be achieved by utilizing the difference between the final temperature and the initial temperature. Trend analysis was used to simulate daily and nightly temperature changes for parameters of maximum monthly temperature, maximum annually temperature based on maximum monthly temperature, median monthly temperature, maximum annually temperature based on median monthly temperature, minimum monthly temperature and minimum annual temperature.
Results and Discussion
Daily temperature data in the Central Plateau of Iran, which includes monthly minimum temperature, annual minimum temperature, monthly maximum temperature, annual maximum temperature based on monthly maximum temperature, monthly median temperature and annual maximum temperature based on monthly median temperature, common in Semnan and Isfahan provinces, showed a significant increase in linear correlation according to the results. In Isfahan province, the linear correlation decreased significantly between the maximum annual temperature based on the maximum monthly temperature and the median monthly temperature. There was no significant trend in other provinces. The linear correlation between temperature data in Isfahan and Semnan provinces, including the minimum monthly, minimum annual, maximum annual, and median monthly temperature, decreased significantly. The linear correlation between average annual temperature, average monthly temperature, maximum annual temperature determined by maximum monthly temperature, average monthly temperature, and maximum annual temperature determined by median monthly temperature increased significantly in Yazd and Isfahan provinces. No significant trends were observed in other provinces. To estimate the amount and approximate number of significant increases and decreases, simulations of temperature changes were conducted. The range and approximate range of numbers for significant increase and decrease in temperature were calculated in degrees Celsius. In all analyses, the parts with higher temperatures had a reddish color. The intensity of the red color increased as the temperature increased, and as the temperature decreased, the red color became fainter and turned blue. The central plateau of Iran recorded a maximum temperature of 44C°and a minimum temperature of -7C°according to this study. The central plateau of Iran has three main provinces, which include Isfahan, Semnan, and Yazd. Considering the temperatures mentioned for these three provinces, the temperatures obtained from this study are very similar, which means that the conducted study is approved to a large extent. Animals are considered to be at risk due to temperature changes. Future research should emphasize the impact of climate change and temperature increase on the living conditions of various animals, particularly those found on the central plateau of Iran.
The temperature of the earth has been rising by about 0.74 degrees Celsius over the past century. A gradual increase in the average annual temperature has been reported by many researchers worldwide, while other reports suggest a decrease in this parameter. The assumption is that there will be more areas of the world experiencing higher temperatures. The climate changes are effectively represented by temperature changes, which is considered one of the main indicators in climate studies. The chemical composition of the atmosphere has changed because of the increase in human industrial activities, so it is responsible for unprecedented changes in the global climate in the past century. The increase in greenhouse gas concentration is the cause of this change. The evidence indicates that the increase in atmospheric gas concentration has caused a significant increase in global temperature. The use of thermal data from sensors is widely used in the study of terrestrial phenomena, as indicated by many studies. The temperature of the earth's surface is directly and indirectly linked to all human activities. It is still not possible to calculate the temperature of the earth's surface with perfect and accurate methods, but some sensors with suitable temporal, spectral, and spatial performance are able to take photos of the entire surface of the Earth. The study is more important due to the fact that various species of animals, such as Jebeer (belonging to the Bovidae), are exposed to climate changes in arid and desert areas. Due to its impact on humans, other creatures, and the entire environment, it is imperative to pay attention to climate change nowadays. In this regard, the main aim of the current study is to evaluate the LST (Land Surface Temperature) trends, changes, and temperature threats of the land surface in the Central Plateau of Iran. Time series remote sensing data of the MODIS (MOD11A2) sensor and Terra satellite, in 8 days with spatial resolution of 1km from 2002 to 2018 have been used.
Material and Methods
The current study has been focused on the central plateau of Iran. The central plateau of Iran lies within the arid lands belt of the northern hemisphere. The current study has been attempting to extract exact information from the images by employing specific techniques. To achieve this goal, the MOD11A2 product of Terra satellite MODIS sensor, the trend of temperature changes and time series construction of the significance of Man Kendall methods and linear correlation parameters such as maximum monthly temperature, maximum annually temperature based on maximum monthly temperature, median monthly temperature, maximum annually temperature based on median monthly temperature, minimum monthly temperature, minimum annually temperature for daily and nightly temperature were used in TerrSet software and Earth Trends Modeler section to extract significant increasing and decreasing areas. After identifying some parts of provinces with significant temperatures based on analysis and results, we can identify the vital numerical value of the temperature in each pixel of those significant parts in the next stage. This can be achieved by utilizing the difference between the final temperature and the initial temperature. Trend analysis was used to simulate daily and nightly temperature changes for parameters of maximum monthly temperature, maximum annually temperature based on maximum monthly temperature, median monthly temperature, maximum annually temperature based on median monthly temperature, minimum monthly temperature and minimum annual temperature.
Results and Discussion
Daily temperature data in the Central Plateau of Iran, which includes monthly minimum temperature, annual minimum temperature, monthly maximum temperature, annual maximum temperature based on monthly maximum temperature, monthly median temperature and annual maximum temperature based on monthly median temperature, common in Semnan and Isfahan provinces, showed a significant increase in linear correlation according to the results. In Isfahan province, the linear correlation decreased significantly between the maximum annual temperature based on the maximum monthly temperature and the median monthly temperature. There was no significant trend in other provinces. The linear correlation between temperature data in Isfahan and Semnan provinces, including the minimum monthly, minimum annual, maximum annual, and median monthly temperature, decreased significantly. The linear correlation between average annual temperature, average monthly temperature, maximum annual temperature determined by maximum monthly temperature, average monthly temperature, and maximum annual temperature determined by median monthly temperature increased significantly in Yazd and Isfahan provinces. No significant trends were observed in other provinces. To estimate the amount and approximate number of significant increases and decreases, simulations of temperature changes were conducted. The range and approximate range of numbers for significant increase and decrease in temperature were calculated in degrees Celsius. In all analyses, the parts with higher temperatures had a reddish color. The intensity of the red color increased as the temperature increased, and as the temperature decreased, the red color became fainter and turned blue. The central plateau of Iran recorded a maximum temperature of 44C°and a minimum temperature of -7C°according to this study. The central plateau of Iran has three main provinces, which include Isfahan, Semnan, and Yazd. Considering the temperatures mentioned for these three provinces, the temperatures obtained from this study are very similar, which means that the conducted study is approved to a large extent. Animals are considered to be at risk due to temperature changes. Future research should emphasize the impact of climate change and temperature increase on the living conditions of various animals, particularly those found on the central plateau of Iran.
Introduction Extreme precipitation has a significant impact on the frequency, severity, and duration of natural hazards, such as floods, droughts, and landslides. This has a significant impact on human life, the economy, natural... more
Introduction
Extreme precipitation has a significant impact on the frequency, severity, and duration of natural hazards, such as floods, droughts, and landslides. This has a significant impact on human life, the economy, natural ecosystems, and agriculture (Song et al, 2015: 34). Between 1880 and 2012, there was a 0.85 °C increase in the average global temperature, with a general increase in precipitation in the mid-latitudes of the Northern Hemisphere (IPCC, 2013: 2; Lio et al, 2017: 822). In addition, there is a possibility of a rise in extreme precipitation in the future (Klein Tank et al, 2006: 1), and so far, the reason for these changes and their relationship with the general circulation of the atmosphere have not been considered. The aim of this study is to analyze the trend of changes in extreme precipitation indices in northwestern Iran and its association with the general circulation of the atmosphere.
Material and Methods
In order to analyze the changes in extreme precipitation events in northwestern Iran, daily precipitation data was collected from 20 synoptic stations in the region between 1986 and 2010. The region that is being studied encompasses West Azerbaijan, East Azerbaijan, Ardabil, Zanjan, and Kurdistan. In assessing limit events, high quality and reliable long-term climate data with daily (or higher) resolution is required (Clintanak et al., 2009: 9). The first step was to examine the quality control and homogeneity of data. The RClimDex software package, introduced as a standard tool by ETCCDI, was used to perform quality control and evaluate data homogeneity in this research. The Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI) introduced 11 indexes to examine changes in precipitation level indices in northwest Iran. RClimDex software calculates these indicators with a significance level of 0.05. This process seeks to establish a standard set of indicators to examine and compare the characteristics of
different regions. The software was used to calculate precipitation indices and display the trend and rate of change on a map.
Results and Discussion
The extreme precipitation indices were calculated to determine the regional trend and percentage of stations with positive and negative trends for the studied stations in northwestern Iran. Afterward, a map was created showing the spatial distribution of the slope for each of the indices. All precipitation indexes, except for the maximum growth period index (CDD), are declining according to the results. The probability of precipitation has decreased due to the more stable winter atmosphere in the region from the point of view of general atmospheric circulation. The region's spring atmosphere, similar to that of winter, shows an increase in stability, which will result in less rainfall. In summer, except for the coastal provinces of the Caspian Sea and the coasts of the Oman Sea, the rest of the country has recorded a decrease in rainfall of 1 mm per day. Most parts of the country experienced an increase in atmosphere thickness to 6 meters in autumn in the study area. Autumn in the region is typically stable and barotropic, but the study area is experiencing less rainfall. This study examines the trend of changes in extreme precipitation indices in northwestern Iran and its relation to a large-scale general circulation of the atmosphere. According to the results, 75% of stations in the region are experiencing a decrease in the maximum daily rainfall (RX1day) and 80% are experiencing a decrease in the maximum five-day rainfall (RX5day). While both the very wet (R95P) and ultra-wet (R99P) day indices are experiencing a downward trend, the R95P index is experiencing a more pronounced downward trend. All three indices R10, R20, and R25 have been declining for the past 25 years, but the R10 index has fallen more rapidly than the other two indices. Sarab station has a positive CWD trend alone, while other stations have a negative and decreasing trend of this index. In most stations throughout the region, the CDD index is increasing. In 85% of stations in the region, the PRCPTOT index is decreasing and there is a noticeable increase in rainfall. The SDII index is experiencing a decrease in 60% of the stations in northwestern Iran, while an increase is being observed in 40%. All precipitation indices, except for the CDD index, have a decreasing trend in general. Drawing and analyzing combined difference maps for geopotential height parameters of 500 hPa, relative rotation of 500 hPa, vertical velocity (omega), rainwater and precipitation rate to study the general atmospheric circulation of the region indicates an increase in altitude has led to a 500 hPa increase in climate stability in the study area (northwest of Iran). The study of omega and relative rotation shows that the region is experiencing a decrease in upward currents and positive rotation. The lack of atmospheric moisture load and rainfall in all seasons can be seen in rainfall water difference maps and rates. Precipitation indices and the general circulation model of the region's atmosphere are compared, indicating that the moisture load of the region's atmosphere has decreased, resulting in drought.
Extreme precipitation has a significant impact on the frequency, severity, and duration of natural hazards, such as floods, droughts, and landslides. This has a significant impact on human life, the economy, natural ecosystems, and agriculture (Song et al, 2015: 34). Between 1880 and 2012, there was a 0.85 °C increase in the average global temperature, with a general increase in precipitation in the mid-latitudes of the Northern Hemisphere (IPCC, 2013: 2; Lio et al, 2017: 822). In addition, there is a possibility of a rise in extreme precipitation in the future (Klein Tank et al, 2006: 1), and so far, the reason for these changes and their relationship with the general circulation of the atmosphere have not been considered. The aim of this study is to analyze the trend of changes in extreme precipitation indices in northwestern Iran and its association with the general circulation of the atmosphere.
Material and Methods
In order to analyze the changes in extreme precipitation events in northwestern Iran, daily precipitation data was collected from 20 synoptic stations in the region between 1986 and 2010. The region that is being studied encompasses West Azerbaijan, East Azerbaijan, Ardabil, Zanjan, and Kurdistan. In assessing limit events, high quality and reliable long-term climate data with daily (or higher) resolution is required (Clintanak et al., 2009: 9). The first step was to examine the quality control and homogeneity of data. The RClimDex software package, introduced as a standard tool by ETCCDI, was used to perform quality control and evaluate data homogeneity in this research. The Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI) introduced 11 indexes to examine changes in precipitation level indices in northwest Iran. RClimDex software calculates these indicators with a significance level of 0.05. This process seeks to establish a standard set of indicators to examine and compare the characteristics of
different regions. The software was used to calculate precipitation indices and display the trend and rate of change on a map.
Results and Discussion
The extreme precipitation indices were calculated to determine the regional trend and percentage of stations with positive and negative trends for the studied stations in northwestern Iran. Afterward, a map was created showing the spatial distribution of the slope for each of the indices. All precipitation indexes, except for the maximum growth period index (CDD), are declining according to the results. The probability of precipitation has decreased due to the more stable winter atmosphere in the region from the point of view of general atmospheric circulation. The region's spring atmosphere, similar to that of winter, shows an increase in stability, which will result in less rainfall. In summer, except for the coastal provinces of the Caspian Sea and the coasts of the Oman Sea, the rest of the country has recorded a decrease in rainfall of 1 mm per day. Most parts of the country experienced an increase in atmosphere thickness to 6 meters in autumn in the study area. Autumn in the region is typically stable and barotropic, but the study area is experiencing less rainfall. This study examines the trend of changes in extreme precipitation indices in northwestern Iran and its relation to a large-scale general circulation of the atmosphere. According to the results, 75% of stations in the region are experiencing a decrease in the maximum daily rainfall (RX1day) and 80% are experiencing a decrease in the maximum five-day rainfall (RX5day). While both the very wet (R95P) and ultra-wet (R99P) day indices are experiencing a downward trend, the R95P index is experiencing a more pronounced downward trend. All three indices R10, R20, and R25 have been declining for the past 25 years, but the R10 index has fallen more rapidly than the other two indices. Sarab station has a positive CWD trend alone, while other stations have a negative and decreasing trend of this index. In most stations throughout the region, the CDD index is increasing. In 85% of stations in the region, the PRCPTOT index is decreasing and there is a noticeable increase in rainfall. The SDII index is experiencing a decrease in 60% of the stations in northwestern Iran, while an increase is being observed in 40%. All precipitation indices, except for the CDD index, have a decreasing trend in general. Drawing and analyzing combined difference maps for geopotential height parameters of 500 hPa, relative rotation of 500 hPa, vertical velocity (omega), rainwater and precipitation rate to study the general atmospheric circulation of the region indicates an increase in altitude has led to a 500 hPa increase in climate stability in the study area (northwest of Iran). The study of omega and relative rotation shows that the region is experiencing a decrease in upward currents and positive rotation. The lack of atmospheric moisture load and rainfall in all seasons can be seen in rainfall water difference maps and rates. Precipitation indices and the general circulation model of the region's atmosphere are compared, indicating that the moisture load of the region's atmosphere has decreased, resulting in drought.
Introduction With the increasing world's population, the need for food and medicine, and their continuous supply, are essential for mankind. Medicinal plants are one of the important factors for human life, as they can be used both as... more
Introduction
With the increasing world's population, the need for food and medicine, and their continuous supply, are essential for mankind. Medicinal plants are one of the important factors for human life, as they can be used both as food and medicine. The ancients had a long history of using medicinal plants, and they used their many properties extensively. The scientific name for Caper plant is Capparis spinosa L. Due to its resistance to environmental stress and its ability to act as a protector against soil destruction, this valuable medicinal plant is suitable for growing in arid and desert areas. Commercial cultivation of this plant is very valuable because it is rich in bioactive compounds. This plant's compounds can be extremely useful and effective in protecting humans from various diseases or enhancing the treatment of diseases. This study aimed to examine the total phenol and flavonoid composition, antioxidant activity, and extraction efficacy of various parts of this plant in two desert locations in Yazd and Isfahan to select the best cultivation region from these two sites for expanding cultivation. To determine the most effective compounds and the optimal extraction method, various organs of the plant were examined separately in this research. The best extraction efficiency can be achieved by growing the plant in the region and harvesting the desired organ, and the extracted materials can be used to prevent and treat diseases.
Material and Methods
The caper plant was collected from desert sites in Yazd and Isfahan in different parts, which included leaves, stems, buds, flowers, fruits, and roots. Plants were collected from four different locations on the site, and finally, the plants from four different locations were combined. After the botany expert's approval, extraction was done from different parts of the plant with hydroalcoholic solvent (80% ethanol) by the Soxhlet method. In this research, different experiments of total phenol, total flavonoid, antioxidant content, and extraction efficiency were performed using standard methods. Different dilutions of extract and standard material were made for all experiments. Folin Ciocalto's reagent was used to measure the total phenol, and it was reported according to the Gallic Acid standard per gram dry weight of the plant. Different tests like ABTS, DPPH, CUPRAC, and FRAP were employed to measure the plant's antioxidant content. The standard for milligrams of Trolox per gram of dried plant weight was used to calculate all of them. The number of flavonoids was measured based on the Aluminium Chloride colorimetry method and was expressed in the standard form of milligrams of Quercetin per gram of weight of the dried plant. To determine the extraction efficiency, the weight of the powder extract obtained from the extraction of different organs was calculated with a scale, and then the ratio of the weight of the powder extract of the weight of dried plant was reported as extraction method efficiency. For each of the experiments, 3 repetitions were performed. A two-way analysis of variance was utilized to examine the data's normality, and finally, IBM SPSS Statistics 26 software was utilized to analyse them.
Results and Discussion
The findings demonstrated that phenolic and flavonoid compounds were abundant in various parts of the caper plant from both locations. The leaves demonstrated a higher concentration of phenolic and flavonol compounds, with 48.611 mgGA/gDW and 19.842 mgQE/gDW, respectively. The antioxidant activity of roots was the highest among all parts of the plant. The Yazd site's caper plants were found to have a higher total phenolic and flavonoid content, with 35.572 mgGA/gDW and 14.14.164 mgQE/gDW, when compared to the other regions. The highest antioxidant activity was found in the fruit and root of the caper plant using the DPPH method. The ABTS method's measurement of antioxidant activity resulted in the same results and indicated that fruits had the highest activity. A positive correlation was observed between the amount of phenol and flavonoids. Furthermore, the Yazd site had a higher extraction efficiency than the Isfahan site, measuring 16.754%. The best region between two desert sites is also the best organ for extraction, as per the results of the current investigation. These results can be utilized to cultivate caper plants that contain more effective substances. These findings emphasize the status of the Caper plant as a rich source of secondary metabolites and show its potential as a potent healing agent with highly beneficial compounds, the site of Yazd is a suitable site for the cultivation of this plant. By cultivating this plant, in addition to helping to reduce desertification and prevent soil erosion, it is possible to have a source of secondary metabolites, especially phenol and flavonoid compounds, and use them in many medicinal applications.
With the increasing world's population, the need for food and medicine, and their continuous supply, are essential for mankind. Medicinal plants are one of the important factors for human life, as they can be used both as food and medicine. The ancients had a long history of using medicinal plants, and they used their many properties extensively. The scientific name for Caper plant is Capparis spinosa L. Due to its resistance to environmental stress and its ability to act as a protector against soil destruction, this valuable medicinal plant is suitable for growing in arid and desert areas. Commercial cultivation of this plant is very valuable because it is rich in bioactive compounds. This plant's compounds can be extremely useful and effective in protecting humans from various diseases or enhancing the treatment of diseases. This study aimed to examine the total phenol and flavonoid composition, antioxidant activity, and extraction efficacy of various parts of this plant in two desert locations in Yazd and Isfahan to select the best cultivation region from these two sites for expanding cultivation. To determine the most effective compounds and the optimal extraction method, various organs of the plant were examined separately in this research. The best extraction efficiency can be achieved by growing the plant in the region and harvesting the desired organ, and the extracted materials can be used to prevent and treat diseases.
Material and Methods
The caper plant was collected from desert sites in Yazd and Isfahan in different parts, which included leaves, stems, buds, flowers, fruits, and roots. Plants were collected from four different locations on the site, and finally, the plants from four different locations were combined. After the botany expert's approval, extraction was done from different parts of the plant with hydroalcoholic solvent (80% ethanol) by the Soxhlet method. In this research, different experiments of total phenol, total flavonoid, antioxidant content, and extraction efficiency were performed using standard methods. Different dilutions of extract and standard material were made for all experiments. Folin Ciocalto's reagent was used to measure the total phenol, and it was reported according to the Gallic Acid standard per gram dry weight of the plant. Different tests like ABTS, DPPH, CUPRAC, and FRAP were employed to measure the plant's antioxidant content. The standard for milligrams of Trolox per gram of dried plant weight was used to calculate all of them. The number of flavonoids was measured based on the Aluminium Chloride colorimetry method and was expressed in the standard form of milligrams of Quercetin per gram of weight of the dried plant. To determine the extraction efficiency, the weight of the powder extract obtained from the extraction of different organs was calculated with a scale, and then the ratio of the weight of the powder extract of the weight of dried plant was reported as extraction method efficiency. For each of the experiments, 3 repetitions were performed. A two-way analysis of variance was utilized to examine the data's normality, and finally, IBM SPSS Statistics 26 software was utilized to analyse them.
Results and Discussion
The findings demonstrated that phenolic and flavonoid compounds were abundant in various parts of the caper plant from both locations. The leaves demonstrated a higher concentration of phenolic and flavonol compounds, with 48.611 mgGA/gDW and 19.842 mgQE/gDW, respectively. The antioxidant activity of roots was the highest among all parts of the plant. The Yazd site's caper plants were found to have a higher total phenolic and flavonoid content, with 35.572 mgGA/gDW and 14.14.164 mgQE/gDW, when compared to the other regions. The highest antioxidant activity was found in the fruit and root of the caper plant using the DPPH method. The ABTS method's measurement of antioxidant activity resulted in the same results and indicated that fruits had the highest activity. A positive correlation was observed between the amount of phenol and flavonoids. Furthermore, the Yazd site had a higher extraction efficiency than the Isfahan site, measuring 16.754%. The best region between two desert sites is also the best organ for extraction, as per the results of the current investigation. These results can be utilized to cultivate caper plants that contain more effective substances. These findings emphasize the status of the Caper plant as a rich source of secondary metabolites and show its potential as a potent healing agent with highly beneficial compounds, the site of Yazd is a suitable site for the cultivation of this plant. By cultivating this plant, in addition to helping to reduce desertification and prevent soil erosion, it is possible to have a source of secondary metabolites, especially phenol and flavonoid compounds, and use them in many medicinal applications.
Introduction Dust is a phenomenon that is mostly seen in arid and semi-arid areas due to high wind speeds and turbulence on the soil surface without vegetation, and prone to erosion. Wind erosion and its dust are a result of various... more
Introduction
Dust is a phenomenon that is mostly seen in arid and semi-arid areas due to high wind speeds and turbulence on the soil surface without vegetation, and prone to erosion. Wind erosion and its dust are a result of various factors including wind speed, vegetation cover, soil characteristics, and climatic conditions. The interaction of all of them leads to an increase or decrease in wind erosion and dust storms. The absence of sufficient information about the prevailing conditions in the region, and knowledge about sensitive and prone areas to dust storms is the cause of the problems caused by them. To address this phenomenon and provide effective management solutions, it is necessary to understand the areas that are most susceptible to dust and the factors that contribute to its occurrence. Remote sensing and modeling can be highly effective in investigating the dust phenomenon in this regard. Remote sensing data and machine learning have been utilized in numerous studies to investigate dust storms and their sources, as well as to model areas that are susceptible to this phenomenon. Although Isfahan province is considered one of the most significant geographical regions of the country, it is prone to repeated droughts, desertification, and dust storms due to its special geographical location, low rainfall, and proximity to the desert. Conducting studies that will lead us to a better understanding of dust-prone areas in this province is necessary. Therefore, In the current research, zoning of dust-prone areas in Isfahan province was done using meteorological codes related to dust, aerosol optical depth values of MODIS sensor of Terra satellite (2001-2022), and machine learning algorithms including RF, BRT, SVM, and CART.
Material and Methods
Isfahan Province with an area of nearly 107017 km2, is located between 30° 43′ to 34° 30′ N and 49° 38′ to 55° 31′ E in Central Iran (Fig. 1). This province experiences an annual rainfall of between 40 mm and more than 800 mm. According to the Iran Meteorological Organization, the average annual temperature is between 10 °C and 20 °C. According to the Thornthwaite method, the climate of Isfahan province is arid in 58.73% of its area (eastern, northeastern, and sub-central parts of the province), semi-arid in 28% of its area (central
and northern parts of the province), and humid and semi-humid in 13.27% of its area (western and southern parts of the province). The first step was to determine the occurrence and non-occurrence points of dust through the use of AOD values. Predictive factors were determined by analyzing 10 different factors, which include land use, temperature, rainfall, erosive wind speed, slope, altitude, albedo, EVI, NDSI, and NDMI. The variance inflation factor (VIF) was used to calculate the correlation between the predictive factors in the next step. Machine learning algorithms were employed to model areas susceptible to dust, and the jackknife test was used to determine the significance of predictive factors in zoning. The model was verified by measuring the value of the area under the ROC curve (ROC-AUC).
Results and Discussion
According to the zoning map for dust-prone areas in Isfahan province, areas with low altitude and flat parts of the north, parts of the northeast, southeast of the province, and the central areas towards the southwest and west of Isfahan province are susceptible to dust. In the RF model, the very low class had the highest percentage of areas that were prone to dust, with a value of 21.36%, and in the BRT model, 22.66% was in the medium class, and in the SVM and CART models, it was very high and low classes with values of 23.92% and 37.6%, respectively. The results of validation illustrated that the RF model with AUC of 0.86 was the most efficient, followed by BRT, CART, and SVM models with AUC values of 0.82, 0.79, and 0.77 respectively. According to the Jackknife test results, in RF, BRT, and CART models, rainfall had the most effect in modeling, while in the SVM model, temperature and rainfall had the most effect in the modeling. The results indicate that salty, barren, and rangeland with poor quality are the most susceptible areas to dust. The lack of vegetation or weak vegetation is a result of the low amount of surface soil moisture, lowest rainfall, and highest temperature in these areas. These areas are susceptible to dust, and when winds blow at a speed above the threshold for wind erosion, dust storms will happen. The validation results indicate that the RF model is the most effective among the applied models, followed by BRT, CART, and SVM models. The Random Forest algorithm is an advanced decision tree model that is utilized for classification and regression. This algorithm's performance is significantly better than other simple regression trees or parametric statistical methods, and it is determined by a large number of decision trees. Rainfall was identified as the most important factor in RF, BRT, and CART models by the jackknife test results. In the RF model, which is considered the best model, the temperature and altitude factors are more important than other factors, after the rainfall factor. The low rainfall in dust-prone areas can lead to soil dryness and low vegetation, which increases the conditions for wind erosion and dust.
Dust is a phenomenon that is mostly seen in arid and semi-arid areas due to high wind speeds and turbulence on the soil surface without vegetation, and prone to erosion. Wind erosion and its dust are a result of various factors including wind speed, vegetation cover, soil characteristics, and climatic conditions. The interaction of all of them leads to an increase or decrease in wind erosion and dust storms. The absence of sufficient information about the prevailing conditions in the region, and knowledge about sensitive and prone areas to dust storms is the cause of the problems caused by them. To address this phenomenon and provide effective management solutions, it is necessary to understand the areas that are most susceptible to dust and the factors that contribute to its occurrence. Remote sensing and modeling can be highly effective in investigating the dust phenomenon in this regard. Remote sensing data and machine learning have been utilized in numerous studies to investigate dust storms and their sources, as well as to model areas that are susceptible to this phenomenon. Although Isfahan province is considered one of the most significant geographical regions of the country, it is prone to repeated droughts, desertification, and dust storms due to its special geographical location, low rainfall, and proximity to the desert. Conducting studies that will lead us to a better understanding of dust-prone areas in this province is necessary. Therefore, In the current research, zoning of dust-prone areas in Isfahan province was done using meteorological codes related to dust, aerosol optical depth values of MODIS sensor of Terra satellite (2001-2022), and machine learning algorithms including RF, BRT, SVM, and CART.
Material and Methods
Isfahan Province with an area of nearly 107017 km2, is located between 30° 43′ to 34° 30′ N and 49° 38′ to 55° 31′ E in Central Iran (Fig. 1). This province experiences an annual rainfall of between 40 mm and more than 800 mm. According to the Iran Meteorological Organization, the average annual temperature is between 10 °C and 20 °C. According to the Thornthwaite method, the climate of Isfahan province is arid in 58.73% of its area (eastern, northeastern, and sub-central parts of the province), semi-arid in 28% of its area (central
and northern parts of the province), and humid and semi-humid in 13.27% of its area (western and southern parts of the province). The first step was to determine the occurrence and non-occurrence points of dust through the use of AOD values. Predictive factors were determined by analyzing 10 different factors, which include land use, temperature, rainfall, erosive wind speed, slope, altitude, albedo, EVI, NDSI, and NDMI. The variance inflation factor (VIF) was used to calculate the correlation between the predictive factors in the next step. Machine learning algorithms were employed to model areas susceptible to dust, and the jackknife test was used to determine the significance of predictive factors in zoning. The model was verified by measuring the value of the area under the ROC curve (ROC-AUC).
Results and Discussion
According to the zoning map for dust-prone areas in Isfahan province, areas with low altitude and flat parts of the north, parts of the northeast, southeast of the province, and the central areas towards the southwest and west of Isfahan province are susceptible to dust. In the RF model, the very low class had the highest percentage of areas that were prone to dust, with a value of 21.36%, and in the BRT model, 22.66% was in the medium class, and in the SVM and CART models, it was very high and low classes with values of 23.92% and 37.6%, respectively. The results of validation illustrated that the RF model with AUC of 0.86 was the most efficient, followed by BRT, CART, and SVM models with AUC values of 0.82, 0.79, and 0.77 respectively. According to the Jackknife test results, in RF, BRT, and CART models, rainfall had the most effect in modeling, while in the SVM model, temperature and rainfall had the most effect in the modeling. The results indicate that salty, barren, and rangeland with poor quality are the most susceptible areas to dust. The lack of vegetation or weak vegetation is a result of the low amount of surface soil moisture, lowest rainfall, and highest temperature in these areas. These areas are susceptible to dust, and when winds blow at a speed above the threshold for wind erosion, dust storms will happen. The validation results indicate that the RF model is the most effective among the applied models, followed by BRT, CART, and SVM models. The Random Forest algorithm is an advanced decision tree model that is utilized for classification and regression. This algorithm's performance is significantly better than other simple regression trees or parametric statistical methods, and it is determined by a large number of decision trees. Rainfall was identified as the most important factor in RF, BRT, and CART models by the jackknife test results. In the RF model, which is considered the best model, the temperature and altitude factors are more important than other factors, after the rainfall factor. The low rainfall in dust-prone areas can lead to soil dryness and low vegetation, which increases the conditions for wind erosion and dust.
Introduction Soil erosion is a serious threat to human well-being and life, especially in arid and semi-arid regions, and is one of the important issues in land management. Rill erosion is one of the most significant events in water... more
Introduction
Soil erosion is a serious threat to human well-being and life, especially in arid and semi-arid regions, and is one of the important issues in land management. Rill erosion is one of the most significant events in water erosion that affect soil loss, landscape, water resources, and land degradation can cause significant loss of soil in different climates. Identifying the effective processes that lead to the creation and expansion of rill erosion is necessary, and finding effective solutions to prevent rills is essential. In the meantime, one of the management solutions is determining the prone area to rill erosion. The high sensitivity of the lands of Nehbandan city (Kaji wetland watershed) to erosion is the reason for determining the prone areas to rill erosion. The maximum entropy method was used to identify the area that is susceptible to rill erosion.
Material and Methods
The modeling process used 9 effective factors, including height, slope steepness, slope direction, rainfall, land use, land cover, soil texture, geomorphology, and geology, based on similar research. Factors affecting the occurrence of rill erosion were analyzed as independent variables. The first step in preparing a rill erosion sensitivity map was to determine the location of rill erosions in the Kaji wetland watershed using Google Earth and then to conduct field surveys. The basin was monitored in the field using GPS and 138 cases of rill erosion were recorded. The occurrence points were divided into two groups: training and validation, with a 70:30 ratio. The total occurrence points were divided into 97 incident points that were randomly selected for model training (validation stage) and 41 incident points that were used for validation purposes. The MaxEnt model relied on the data set used for training as independent variables. In order to use the maximum entropy model to determine rill erosion, first the independent variables (factors affecting the occurrence of rill erosion) and the dependent variable (identification of points with rill erosion) was converted to the required format and introduced to MaxEnt software. To evaluate the effectiveness of the model in detecting occurrence points (rill erosion) from pseudo-non-
occurrence points, the area under the ROC curve was used. The Jack Knife test was utilized to investigate the identification and prioritization of 9 influential factors (independent variables) that influence the results. The model was implemented using the remaining variables as input factors after removing the independent variables separately for this purpose. The efficiency of the model built using all independent variables was measured in comparison to the case where the model was built based on other variables. To determine its effect on the output, the contribution of the omitted independent variable was examined.
Results and Discussion
According to the validation results, the sensitivity map for rill erosion has a high efficiency. The test stage should have a ROC curve of 0.859 (very good) and the test stage should have an average curve of 0.6 (moderate). The Jack Knife test revealed that the slope's steepness was the most significant environmental factor in the predicted sensitivity map for rill erosion in the study area. Geology and land cover were also recognized as other important factors. The MaxEnt model was found to be an effective model for preparing the rill erosion susceptibility map, according to the results. According to the findings, the slope steepness factor, which is 25%, is the main factor that affects the rill erosion of the Kaji wetland watershed. The high frequency of the slope class with a slope class below 20% suggests that this slope class is a significant factor in the development of rill erosion. The geological map of the region indicates that the majority of the region is dedicated to Quaternary formations, which is crucial for the development and creation of erosion in the region. The watershed's proneness to rill erosion is caused by poor rangeland usage. Management of vegetation and rangeland is necessary to reduce the potential for soil erosion in the region. According to the results, the soil texture of the region had less effect on the development of rill erosion; because most of the soil in the area is related to sand-gravel texture, which has a low effect on rill erosion. The MaxEnt model's high accuracy in modeling the sensitivity of rill erosion is evidenced by the results of the present study.
Soil erosion is a serious threat to human well-being and life, especially in arid and semi-arid regions, and is one of the important issues in land management. Rill erosion is one of the most significant events in water erosion that affect soil loss, landscape, water resources, and land degradation can cause significant loss of soil in different climates. Identifying the effective processes that lead to the creation and expansion of rill erosion is necessary, and finding effective solutions to prevent rills is essential. In the meantime, one of the management solutions is determining the prone area to rill erosion. The high sensitivity of the lands of Nehbandan city (Kaji wetland watershed) to erosion is the reason for determining the prone areas to rill erosion. The maximum entropy method was used to identify the area that is susceptible to rill erosion.
Material and Methods
The modeling process used 9 effective factors, including height, slope steepness, slope direction, rainfall, land use, land cover, soil texture, geomorphology, and geology, based on similar research. Factors affecting the occurrence of rill erosion were analyzed as independent variables. The first step in preparing a rill erosion sensitivity map was to determine the location of rill erosions in the Kaji wetland watershed using Google Earth and then to conduct field surveys. The basin was monitored in the field using GPS and 138 cases of rill erosion were recorded. The occurrence points were divided into two groups: training and validation, with a 70:30 ratio. The total occurrence points were divided into 97 incident points that were randomly selected for model training (validation stage) and 41 incident points that were used for validation purposes. The MaxEnt model relied on the data set used for training as independent variables. In order to use the maximum entropy model to determine rill erosion, first the independent variables (factors affecting the occurrence of rill erosion) and the dependent variable (identification of points with rill erosion) was converted to the required format and introduced to MaxEnt software. To evaluate the effectiveness of the model in detecting occurrence points (rill erosion) from pseudo-non-
occurrence points, the area under the ROC curve was used. The Jack Knife test was utilized to investigate the identification and prioritization of 9 influential factors (independent variables) that influence the results. The model was implemented using the remaining variables as input factors after removing the independent variables separately for this purpose. The efficiency of the model built using all independent variables was measured in comparison to the case where the model was built based on other variables. To determine its effect on the output, the contribution of the omitted independent variable was examined.
Results and Discussion
According to the validation results, the sensitivity map for rill erosion has a high efficiency. The test stage should have a ROC curve of 0.859 (very good) and the test stage should have an average curve of 0.6 (moderate). The Jack Knife test revealed that the slope's steepness was the most significant environmental factor in the predicted sensitivity map for rill erosion in the study area. Geology and land cover were also recognized as other important factors. The MaxEnt model was found to be an effective model for preparing the rill erosion susceptibility map, according to the results. According to the findings, the slope steepness factor, which is 25%, is the main factor that affects the rill erosion of the Kaji wetland watershed. The high frequency of the slope class with a slope class below 20% suggests that this slope class is a significant factor in the development of rill erosion. The geological map of the region indicates that the majority of the region is dedicated to Quaternary formations, which is crucial for the development and creation of erosion in the region. The watershed's proneness to rill erosion is caused by poor rangeland usage. Management of vegetation and rangeland is necessary to reduce the potential for soil erosion in the region. According to the results, the soil texture of the region had less effect on the development of rill erosion; because most of the soil in the area is related to sand-gravel texture, which has a low effect on rill erosion. The MaxEnt model's high accuracy in modeling the sensitivity of rill erosion is evidenced by the results of the present study.
Introduction The impact of dust storms on the ecosystem, human health, and economy is significant in the affected areas. In arid and semi-arid regions, dust is a natural occurrence that covers about one third of the earth's surface. This... more
Introduction
The impact of dust storms on the ecosystem, human health, and economy is significant in the affected areas. In arid and semi-arid regions, dust is a natural occurrence that covers about one third of the earth's surface. This phenomenon is caused by wind erosion and factors such as the size of soil particles and their adhesion force, surface roughness, weather conditions such as long-term droughts cause it to intensify. To understand the impact of the dust phenomenon on humans and the environment, it is essential to evaluate the spatial and temporal distribution of dust and its changes and effects. Numerous studies have been carried out in the field of evaluating dust changes using different methods. For example, using CMIP5 models, synoptic fog systems are predicted to increase during the 21st century in the Middle East. In addition, using AOD obtained from MODIS and MERRA-2 sensors, researchers showed a significant upward trend in dust changes from 2000 to 2010. A significant upward trend was shown in Iran's winter AOD values during the period 2000 to 2010, and a decreasing trend during the period 2010 to 2018. A point can be spotted by examining various studies in the Middle East and Iran that evaluate the spatio-temporal changes of dust. Statistical tests of time series study, such as Mann-Kendall spatially and pixel by pixel, have been used in limited research to evaluate the trend of dust changes. In Iran, there is a research gap in not using spatial and pixel-by-pixel statistical tests to evaluate the trend of dust changes, as stated. This research aimed to provide a solution and address the problem by analyzing the spatial and temporal changes of dust using the AOD index in the eastern half of the country.
Material and Methods
In this research, in order to evaluate the temporal-spatial changes of dust, the AOD data of the blue band (470 nm) of the MCD19A2 product of the MODIS sensor was used. AOD parameter is known as one of the most key factors in studying the climatic effects of aerosols and atmospheric pollution. In order to extract AOD data, monthly data from 2001 to 2022 were obtained in the Google Earth Engine system by averaging the daily AOD data. Over a 22-year period, the average of each month was calculated. The months that had the highest average AOD values were chosen and their changes were evaluated. In this research, the Mann-Kendall test was used to evaluate the change process. Menkendall's ZM coefficient was calculated for months in the Earth Trend Modeler (ETM) of the TerrSet software to achieve this. In the next step, the intensity of monthly AOD changes per time unit was calculated for 22 years in selected months. To simulate the process of changes, linear regression analysis can be utilized for this purpose. This method is used to determine the linear relationship between all the data of a dependent variable and the corresponding data of the independent index. If the slope is higher than zero, the dependent variable will change in the same direction as the independent variable. The dependent variable changes in the opposite direction of the independent variable if the slope is smaller than zero. The steeper the slope of changes, the greater the impact of the independent variable on the dependent variable. The Earth Trend Modeler (ETM) of TerrSet software also carried out this step.
Results and Discussion
Based on the evaluation of the monthly average AOD changes in the studied area, the trend and intensity of AOD changes from 2001 to 2022 were assessed in April, May, June, and July. In most areas of the studied area, AOD is increasing with a probability of more than 70%, and the intensity of changes is mostly high and very high in April. It can be concluded that AOD is experiencing a strong increase in April. This is despite the fact that in May, June and July, respectively, a considerable part of the western half, northern half and eastern half is increasing with different intensities with a probability of more than 70%. It can be concluded that the trend and intensity of AOD changes in the above-mentioned months follow a different spatial pattern. The dispersion of dust production centers inside and outside Iran, and the local and regional synoptic conditions governing dust production centers is the cause of changes in the spatio-temporal patterns of dust storms. The unprincipled extraction of water resources by humans, land degradation, soil moisture reduction, and the loss of vegetation due to climate change all affect these factors in turn. The results showed that the monitoring of monthly average AOD changes can help to identify new hotspots and evaluate the results of wind and dust erosion control and management activities. Therefore, it can be suggested that a system based on remote sensing must be designed and presented to monitor dust changes, so that the management of the dust phenomenon in Iran becomes more. We need to pay attention to the factors that influence these changes and evaluate their impact on the dust phenomenon. On the other hand, by modeling the environmental factors affecting on the trend of dust changes in each region by using methods such as dust evaluation, it is possible to determine the role of each factor and the most important factor affecting the trend of dust changes in each region.
The impact of dust storms on the ecosystem, human health, and economy is significant in the affected areas. In arid and semi-arid regions, dust is a natural occurrence that covers about one third of the earth's surface. This phenomenon is caused by wind erosion and factors such as the size of soil particles and their adhesion force, surface roughness, weather conditions such as long-term droughts cause it to intensify. To understand the impact of the dust phenomenon on humans and the environment, it is essential to evaluate the spatial and temporal distribution of dust and its changes and effects. Numerous studies have been carried out in the field of evaluating dust changes using different methods. For example, using CMIP5 models, synoptic fog systems are predicted to increase during the 21st century in the Middle East. In addition, using AOD obtained from MODIS and MERRA-2 sensors, researchers showed a significant upward trend in dust changes from 2000 to 2010. A significant upward trend was shown in Iran's winter AOD values during the period 2000 to 2010, and a decreasing trend during the period 2010 to 2018. A point can be spotted by examining various studies in the Middle East and Iran that evaluate the spatio-temporal changes of dust. Statistical tests of time series study, such as Mann-Kendall spatially and pixel by pixel, have been used in limited research to evaluate the trend of dust changes. In Iran, there is a research gap in not using spatial and pixel-by-pixel statistical tests to evaluate the trend of dust changes, as stated. This research aimed to provide a solution and address the problem by analyzing the spatial and temporal changes of dust using the AOD index in the eastern half of the country.
Material and Methods
In this research, in order to evaluate the temporal-spatial changes of dust, the AOD data of the blue band (470 nm) of the MCD19A2 product of the MODIS sensor was used. AOD parameter is known as one of the most key factors in studying the climatic effects of aerosols and atmospheric pollution. In order to extract AOD data, monthly data from 2001 to 2022 were obtained in the Google Earth Engine system by averaging the daily AOD data. Over a 22-year period, the average of each month was calculated. The months that had the highest average AOD values were chosen and their changes were evaluated. In this research, the Mann-Kendall test was used to evaluate the change process. Menkendall's ZM coefficient was calculated for months in the Earth Trend Modeler (ETM) of the TerrSet software to achieve this. In the next step, the intensity of monthly AOD changes per time unit was calculated for 22 years in selected months. To simulate the process of changes, linear regression analysis can be utilized for this purpose. This method is used to determine the linear relationship between all the data of a dependent variable and the corresponding data of the independent index. If the slope is higher than zero, the dependent variable will change in the same direction as the independent variable. The dependent variable changes in the opposite direction of the independent variable if the slope is smaller than zero. The steeper the slope of changes, the greater the impact of the independent variable on the dependent variable. The Earth Trend Modeler (ETM) of TerrSet software also carried out this step.
Results and Discussion
Based on the evaluation of the monthly average AOD changes in the studied area, the trend and intensity of AOD changes from 2001 to 2022 were assessed in April, May, June, and July. In most areas of the studied area, AOD is increasing with a probability of more than 70%, and the intensity of changes is mostly high and very high in April. It can be concluded that AOD is experiencing a strong increase in April. This is despite the fact that in May, June and July, respectively, a considerable part of the western half, northern half and eastern half is increasing with different intensities with a probability of more than 70%. It can be concluded that the trend and intensity of AOD changes in the above-mentioned months follow a different spatial pattern. The dispersion of dust production centers inside and outside Iran, and the local and regional synoptic conditions governing dust production centers is the cause of changes in the spatio-temporal patterns of dust storms. The unprincipled extraction of water resources by humans, land degradation, soil moisture reduction, and the loss of vegetation due to climate change all affect these factors in turn. The results showed that the monitoring of monthly average AOD changes can help to identify new hotspots and evaluate the results of wind and dust erosion control and management activities. Therefore, it can be suggested that a system based on remote sensing must be designed and presented to monitor dust changes, so that the management of the dust phenomenon in Iran becomes more. We need to pay attention to the factors that influence these changes and evaluate their impact on the dust phenomenon. On the other hand, by modeling the environmental factors affecting on the trend of dust changes in each region by using methods such as dust evaluation, it is possible to determine the role of each factor and the most important factor affecting the trend of dust changes in each region.
Introduction The growth of plants is affected by environmental stresses, particularly drought and salinity, which are the main problems of arid and semi-arid lands. Germination is a crucial stage in the life of most plants. Plant... more
Introduction
The growth of plants is affected by environmental stresses, particularly drought and salinity, which are the main problems of arid and semi-arid lands. Germination is a crucial stage in the life of most plants. Plant establishment in arid and semi-arid regions requires special tolerance to stresses like salinity and drought during the germination stage. In most plants, increasing salinity and drought stress during the germination stage prevents the plant from germinate. Therefore, knowing the resistance to salinity and drought in different plants can be used in the management of natural environments. Considering the increase in global temperature and the decrease in rainfall in Iran, as well as the soil salinization, it is very important to choose plants with high tolerance to salinity and drought in rangeland. In the southern rangeland of Kohgiluyeh Va Boyer Ahmad province, which are located in arid and semi-arid climates, non-native species such as Atriplex spp. and Prosopis spp. have been used for improvement and restoration in the past decades. The soil and native vegetation of the region are negatively impacted by non-native plants, which have problems like lack of natural regeneration. Identifying suitable native plants that can grow in specific ecological conditions of arid and semi-arid areas, such as drought and salinity, is necessary. The current research aims to identify native resistant species to the mentioned stresses for vegetation restoration in biological and bio-mechanical projects.
Material and Methods
In order to identify the species tolerant to environmental stress in the rangeland of Kohgiluyeh Va Boyer Ahmad province, three native species including Zygophyllum eurypterum Boiss. & Buhse, Sanguisorba minor L. and Salsola orientalis S. G. Gmelin (Salsola rigida) were selected. The habitats of the species were identified through field surveys and the cooperation of experts from the General Department of Natural Resources and Watershed Management of Kohgiluyeh Va Boyer Ahmad province. Sampling of plant seeds for experiments was done in
range habitats. Seed germination reaction of three species Z. eurypterum, S. minor. and S. orientalis were studied in the laboratory with respect to different levels of salinity and drought stress. The drought stress test included six levels (0, -0.3, -0.6, -0.9, -1.2, and -1.5 MP) which were prepared using polyethylene glycol 6000. The second experiment included 6 salinity levels (0, 50, 100, 150, 200, 250 mM). Sodium chloride was used to create salinity stress. Before conducting the salinity and drought tests, treatments were applied to break the seed dormancy of different species, and after identifying the best treatment for each species, dormancy tests were performed. Germination was done as a factorial experiment in a completely randomized design with 4 replications (20 seeds per replication) in a germinator at a temperature of 25°C. During a period of 20 days, every day the germinated seeds whose root length was more than 2 mm were counted and their germination percentage, germination rate, length of root, stem and seedling and their seed germination index were measured. Using SPSSVer.23 software, analysis of variance and comparison of average data was done.
Results and Discussion
Variance analysis shows that there is a significant difference between drought and salinity levels in the traits measured in plants (p<0.01). There is a significant difference between plant species and drought-salinity interaction and species(p<0.01). With the increase of dryness, a significant difference was observed in terms of germination percentage in all three species. In this condition, the highest amount of measured traits including, germination percentage and seed germination index was observed in Z. eurypterum. with increasing salinity, the germination rate of all three species decreases significantly. In the condition without salt stress (control treatment), the highest percentage of germination (77%) was obtained in S. minor. But with increasing salinity levels, the highest germination percentage is observed in S. orientalis, and also with increasing salinity levels, the lowest germination percentage is related to S. minor species. Plants responded differently to environmental stresses, as shown by the results in general. The restoration and improvement of rangelands requires knowledge of plants that are resistant to existing stresses in order to manage natural areas. According to the current research, the rate of germination and growth of seedlings decreases as salinity and drought levels increase. Among the studied species, Z. eurypterum is the most resistant to drought and S. minor is the most sensitive. It can be concluded that the highest germination is observed in S. orientalis, when salinity levels increase, and the lowest germination is observed in S. minor species. Therefore, S. orientalis can be considered as a salt resistant. As the species studied are indigenous and native in the south of Kohgiluyeh Va Boyer Ahmad provinces, the results of this research are suggested for use in biological projects.
The growth of plants is affected by environmental stresses, particularly drought and salinity, which are the main problems of arid and semi-arid lands. Germination is a crucial stage in the life of most plants. Plant establishment in arid and semi-arid regions requires special tolerance to stresses like salinity and drought during the germination stage. In most plants, increasing salinity and drought stress during the germination stage prevents the plant from germinate. Therefore, knowing the resistance to salinity and drought in different plants can be used in the management of natural environments. Considering the increase in global temperature and the decrease in rainfall in Iran, as well as the soil salinization, it is very important to choose plants with high tolerance to salinity and drought in rangeland. In the southern rangeland of Kohgiluyeh Va Boyer Ahmad province, which are located in arid and semi-arid climates, non-native species such as Atriplex spp. and Prosopis spp. have been used for improvement and restoration in the past decades. The soil and native vegetation of the region are negatively impacted by non-native plants, which have problems like lack of natural regeneration. Identifying suitable native plants that can grow in specific ecological conditions of arid and semi-arid areas, such as drought and salinity, is necessary. The current research aims to identify native resistant species to the mentioned stresses for vegetation restoration in biological and bio-mechanical projects.
Material and Methods
In order to identify the species tolerant to environmental stress in the rangeland of Kohgiluyeh Va Boyer Ahmad province, three native species including Zygophyllum eurypterum Boiss. & Buhse, Sanguisorba minor L. and Salsola orientalis S. G. Gmelin (Salsola rigida) were selected. The habitats of the species were identified through field surveys and the cooperation of experts from the General Department of Natural Resources and Watershed Management of Kohgiluyeh Va Boyer Ahmad province. Sampling of plant seeds for experiments was done in
range habitats. Seed germination reaction of three species Z. eurypterum, S. minor. and S. orientalis were studied in the laboratory with respect to different levels of salinity and drought stress. The drought stress test included six levels (0, -0.3, -0.6, -0.9, -1.2, and -1.5 MP) which were prepared using polyethylene glycol 6000. The second experiment included 6 salinity levels (0, 50, 100, 150, 200, 250 mM). Sodium chloride was used to create salinity stress. Before conducting the salinity and drought tests, treatments were applied to break the seed dormancy of different species, and after identifying the best treatment for each species, dormancy tests were performed. Germination was done as a factorial experiment in a completely randomized design with 4 replications (20 seeds per replication) in a germinator at a temperature of 25°C. During a period of 20 days, every day the germinated seeds whose root length was more than 2 mm were counted and their germination percentage, germination rate, length of root, stem and seedling and their seed germination index were measured. Using SPSSVer.23 software, analysis of variance and comparison of average data was done.
Results and Discussion
Variance analysis shows that there is a significant difference between drought and salinity levels in the traits measured in plants (p<0.01). There is a significant difference between plant species and drought-salinity interaction and species(p<0.01). With the increase of dryness, a significant difference was observed in terms of germination percentage in all three species. In this condition, the highest amount of measured traits including, germination percentage and seed germination index was observed in Z. eurypterum. with increasing salinity, the germination rate of all three species decreases significantly. In the condition without salt stress (control treatment), the highest percentage of germination (77%) was obtained in S. minor. But with increasing salinity levels, the highest germination percentage is observed in S. orientalis, and also with increasing salinity levels, the lowest germination percentage is related to S. minor species. Plants responded differently to environmental stresses, as shown by the results in general. The restoration and improvement of rangelands requires knowledge of plants that are resistant to existing stresses in order to manage natural areas. According to the current research, the rate of germination and growth of seedlings decreases as salinity and drought levels increase. Among the studied species, Z. eurypterum is the most resistant to drought and S. minor is the most sensitive. It can be concluded that the highest germination is observed in S. orientalis, when salinity levels increase, and the lowest germination is observed in S. minor species. Therefore, S. orientalis can be considered as a salt resistant. As the species studied are indigenous and native in the south of Kohgiluyeh Va Boyer Ahmad provinces, the results of this research are suggested for use in biological projects.
Introduction One of the environmental challenges in the world is desertification. Desertification is land degradation in arid, semi-arid and dry sub-humid caused by several factors such as climate change and human activities.... more
Introduction
One of the environmental challenges in the world is desertification. Desertification is land degradation in arid, semi-arid and dry sub-humid caused by several factors such as climate change and human activities. Desertification is a significant phenomenon, particularly in arid and semi-arid regions. In many instances, it is seen as a serious threat to human societies. The desertification process in developing countries is very intense, and this issue can have a significant impact on the future of these countries. Iran is a country that is exposed to the phenomenon of desertification. Due to the geographical location, arid and semi-arid areas cover approximately two-thirds of Iran. The desertification phenomenon is present in Yazd province. Due to its climate and hydrogeomorphology, this province, which is located in the central regions of Iran, has a high vulnerability potential against land use changes and desertification. Considering the importance of the topic, this research has identified the vulnerable areas of Yazd province against desertification using the DVI index.
Material and Methods
In this research, library information, statistical data related to the population of Yazd province, climatic data of Yazd province, as well as the 30-meter SRTM DEM as the most important research data were used. The model used in this research was based on DVI vulnerability index. The DVI vulnerability index was the basis for the model used in this research. The time-spatial changes of vulnerability to desertification in the Banas River basin in India have been investigated using the DVI model. The DVI model uses 9 indicators, which are grouped into 4 groups: demographic indicators, weather indicators, topographic indicators, and soil indicators.
Results and Discussion
In this research, in order to identify the vulnerable areas of Yazd province to desertification from demographic indicators (population density, population growth and illiteracy percentage), weather indicators (precipitation rate, average temperature, and evaporation rate and dryness index), topographic indices (slope percentage) and soil science indices (soil type) have been used.
The slope index indicates that the western parts of Yazd province are more vulnerable. According to the geological index, the northern and eastern parts of this province are highly vulnerable. The northern, central, and eastern regions of Yazd province are highly vulnerable in terms of precipitation, average temperature, evaporation, and dryness indicators. Yazd city has a high vulnerability potential in terms of population density index. In terms of population growth index, Ardakan city has a high vulnerability potential and also in terms of illiteracy index, Taft city has a high vulnerability potential. The location of Yazd province has resulted in a large portion of its area being covered in arid and hyper-arid areas. Due to their high vulnerability to erosion, destruction, and vulnerability, many parts of this province are prone to desertification. The DVI model was used to evaluate the vulnerability potential of Yazd province against desertification in this research. The DVI model results are divided into 4 vulnerability potential classes: low, medium, high, and very high. The results indicate that the class with a high vulnerability potential covers 42.9% of the area, which is primarily concentrated in the northern and central areas of Yazd province. The class with high vulnerability potential covers 41/4 of the area, which primarily encompasses the western regions of Yazd province. The classes with medium and low vulnerability potential are distributed in the central, southeastern, and southern parts of Yazd province, with 14.3 and 1.4 percent of the area, respectively. The vulnerability status of cities in Yazd province has been assessed in this research. Khatam and Bahabad cities have the lowest vulnerability percentage, while Yazd, Meibod, and Ardakan cities have the highest vulnerability potential, according to the results. Many parts of Yazd province, including its northern and central regions, have a high vulnerability potential, which requires special attention and the implementation of long-term programs to prevent vulnerability and increase desertification.
One of the environmental challenges in the world is desertification. Desertification is land degradation in arid, semi-arid and dry sub-humid caused by several factors such as climate change and human activities. Desertification is a significant phenomenon, particularly in arid and semi-arid regions. In many instances, it is seen as a serious threat to human societies. The desertification process in developing countries is very intense, and this issue can have a significant impact on the future of these countries. Iran is a country that is exposed to the phenomenon of desertification. Due to the geographical location, arid and semi-arid areas cover approximately two-thirds of Iran. The desertification phenomenon is present in Yazd province. Due to its climate and hydrogeomorphology, this province, which is located in the central regions of Iran, has a high vulnerability potential against land use changes and desertification. Considering the importance of the topic, this research has identified the vulnerable areas of Yazd province against desertification using the DVI index.
Material and Methods
In this research, library information, statistical data related to the population of Yazd province, climatic data of Yazd province, as well as the 30-meter SRTM DEM as the most important research data were used. The model used in this research was based on DVI vulnerability index. The DVI vulnerability index was the basis for the model used in this research. The time-spatial changes of vulnerability to desertification in the Banas River basin in India have been investigated using the DVI model. The DVI model uses 9 indicators, which are grouped into 4 groups: demographic indicators, weather indicators, topographic indicators, and soil indicators.
Results and Discussion
In this research, in order to identify the vulnerable areas of Yazd province to desertification from demographic indicators (population density, population growth and illiteracy percentage), weather indicators (precipitation rate, average temperature, and evaporation rate and dryness index), topographic indices (slope percentage) and soil science indices (soil type) have been used.
The slope index indicates that the western parts of Yazd province are more vulnerable. According to the geological index, the northern and eastern parts of this province are highly vulnerable. The northern, central, and eastern regions of Yazd province are highly vulnerable in terms of precipitation, average temperature, evaporation, and dryness indicators. Yazd city has a high vulnerability potential in terms of population density index. In terms of population growth index, Ardakan city has a high vulnerability potential and also in terms of illiteracy index, Taft city has a high vulnerability potential. The location of Yazd province has resulted in a large portion of its area being covered in arid and hyper-arid areas. Due to their high vulnerability to erosion, destruction, and vulnerability, many parts of this province are prone to desertification. The DVI model was used to evaluate the vulnerability potential of Yazd province against desertification in this research. The DVI model results are divided into 4 vulnerability potential classes: low, medium, high, and very high. The results indicate that the class with a high vulnerability potential covers 42.9% of the area, which is primarily concentrated in the northern and central areas of Yazd province. The class with high vulnerability potential covers 41/4 of the area, which primarily encompasses the western regions of Yazd province. The classes with medium and low vulnerability potential are distributed in the central, southeastern, and southern parts of Yazd province, with 14.3 and 1.4 percent of the area, respectively. The vulnerability status of cities in Yazd province has been assessed in this research. Khatam and Bahabad cities have the lowest vulnerability percentage, while Yazd, Meibod, and Ardakan cities have the highest vulnerability potential, according to the results. Many parts of Yazd province, including its northern and central regions, have a high vulnerability potential, which requires special attention and the implementation of long-term programs to prevent vulnerability and increase desertification.
Introduction Widespread lands in arid, semi-arid, or dry sub-humid areas of the world have been influenced by the consequences of the land degradation resulting from natural factors and human activities like agriculture, changes in the... more
Introduction
Widespread lands in arid, semi-arid, or dry sub-humid areas of the world have been influenced by the consequences of the land degradation resulting from natural factors and human activities like agriculture, changes in the land use. A large part of Iran is located in arid and semi-arid regions. The degradation of soil can be greatly impacted by agricultural activities, incorrect management, and improper land management. The most suitable solution to reduce the negative effects of land use change on the desert is to choose the best type of land management with the least degradation. The fragile nature of these ecosystems and the large area of arid and semi-arid areas of the country require proper and accurate management. Soil is an important and valuable terrestrial source of OC storage, which plays a significant role in the global C cycle by storing about 1500 billion tons of C. The total C in microbial biomass is 1.4% of the total SOC. demonstrating the significant contribution of this sector to the global C cycle. Land use change can be one of the most important factors of land degradation that affects the quality and quantity of soil organic C, and soil characteristics. The present study was done to investigate the role of different land uses including rangeland as control, abandoned land, Triticum aestivum L. cultivation, Hordeum vulgare L. cultivated lands and Medicago sativa L. cultivation, on some soil microbial indices such as basal soil respiration, substrate induced respiration, microbial biomass carbon, microbial biomass nitrogen, microbial quotient, metabolic coefficient and carbon access index, in Lasjerd , Semnan province in two depths of 0 to 10 cm and 10 to 30 cm.
Material and Methods
The initial step was to select various treatments that included rangeland as control treatment, abandoned land, Triticum aestivum cultivation, Hordeum vulgare cultivated lands and Medicago sativa cultivation. In the second step, soil sampling was performed at two depths of 0-10 and 10-30 cm in five replications. In this regard, one soil profile in the center and four other profiles were dug in the form of a cross, considering the marginal effect. The samples needed for soil biological tests were carried and stored in the refrigerator containing dry ice and biological tests were performed later. The considered factors were measured by valid scientific guidelines and methods. Data related to soil microbial properties were analyzed by a factorial test in the form of
a completely random design with five repetitions. All statistical computing was done using SPSS 19 software and the mean comparison tests were performed by Duncan test.
Results and Discussion
The results of the present study indicated that there is significant impact of the treatments on the properties studied at the two depths, at the first soil layer equals to the depth of 0 to 10 cm, basal soil respiration, substrate induced respiration, microbial biomass carbon, microbial biomass nitrogen, microbial quotient, and metabolic coefficient have been affected by different land uses, as the highest level of basal soil respiration in the abandoned land equals to 0.424 mgCO2g-1dm24h-1 and the lowest in Triticum aestivum cultivation 0.006 mgCO2g-1dm24h-1, as well as the second depth- 10 to 30 cm- basal soil respiration, microbial quotient, metabolic coefficient are affected by different types of land uses. The highest amount of metabolic coefficient was observed in abandoned lands as 0.068 mgCO2-Cg-1MBCday-1 and the lowest was found in Medicago sativa cultivation lands equals to 0.013 mgCO2-Cg-1MBCday-1. Soil microbial indices are sensitive to land use changes. The first top 10 cm of the soil studied, has been most affected by these indices.
Due to the failure of soil pedons, the change in land use from rangeland to agricultural lands increases the speed of litter decomposition and decreases the storage of soil nutrients, the microbial population, composition and activity of the soil as an indicator of soil quality, health and fertility. But techniques of no-tillage or minimal-tillage, as well as the principles of sustainable agriculture (such as returning the residues to the soil, proper use of chemical fertilizers, using biological fertilizers, and biological control of pests) cause the destructive process of the biological indices to be adjusted and get balanced in a shorter time period with environment. Considering the changes in the biological indicators of the soil, which have caused the destruction of the cultivated lands in the studied area, it is suggested to rehabilitate the bare lands with native rangeland species of the region, such as Artemisia sieberi Besser, Zygophyllum eurypterum Boiss. & Buhse, and Astragalus tribuloides Delile. Range management plans are the only way to allocate rangelands in the region, and a detailed survey of rangelands in the region is necessary. To prevent land use change, it is important to address the multi-purpose uses of rangelands and the determination of economic units to support the lives of beneficiary households.
Widespread lands in arid, semi-arid, or dry sub-humid areas of the world have been influenced by the consequences of the land degradation resulting from natural factors and human activities like agriculture, changes in the land use. A large part of Iran is located in arid and semi-arid regions. The degradation of soil can be greatly impacted by agricultural activities, incorrect management, and improper land management. The most suitable solution to reduce the negative effects of land use change on the desert is to choose the best type of land management with the least degradation. The fragile nature of these ecosystems and the large area of arid and semi-arid areas of the country require proper and accurate management. Soil is an important and valuable terrestrial source of OC storage, which plays a significant role in the global C cycle by storing about 1500 billion tons of C. The total C in microbial biomass is 1.4% of the total SOC. demonstrating the significant contribution of this sector to the global C cycle. Land use change can be one of the most important factors of land degradation that affects the quality and quantity of soil organic C, and soil characteristics. The present study was done to investigate the role of different land uses including rangeland as control, abandoned land, Triticum aestivum L. cultivation, Hordeum vulgare L. cultivated lands and Medicago sativa L. cultivation, on some soil microbial indices such as basal soil respiration, substrate induced respiration, microbial biomass carbon, microbial biomass nitrogen, microbial quotient, metabolic coefficient and carbon access index, in Lasjerd , Semnan province in two depths of 0 to 10 cm and 10 to 30 cm.
Material and Methods
The initial step was to select various treatments that included rangeland as control treatment, abandoned land, Triticum aestivum cultivation, Hordeum vulgare cultivated lands and Medicago sativa cultivation. In the second step, soil sampling was performed at two depths of 0-10 and 10-30 cm in five replications. In this regard, one soil profile in the center and four other profiles were dug in the form of a cross, considering the marginal effect. The samples needed for soil biological tests were carried and stored in the refrigerator containing dry ice and biological tests were performed later. The considered factors were measured by valid scientific guidelines and methods. Data related to soil microbial properties were analyzed by a factorial test in the form of
a completely random design with five repetitions. All statistical computing was done using SPSS 19 software and the mean comparison tests were performed by Duncan test.
Results and Discussion
The results of the present study indicated that there is significant impact of the treatments on the properties studied at the two depths, at the first soil layer equals to the depth of 0 to 10 cm, basal soil respiration, substrate induced respiration, microbial biomass carbon, microbial biomass nitrogen, microbial quotient, and metabolic coefficient have been affected by different land uses, as the highest level of basal soil respiration in the abandoned land equals to 0.424 mgCO2g-1dm24h-1 and the lowest in Triticum aestivum cultivation 0.006 mgCO2g-1dm24h-1, as well as the second depth- 10 to 30 cm- basal soil respiration, microbial quotient, metabolic coefficient are affected by different types of land uses. The highest amount of metabolic coefficient was observed in abandoned lands as 0.068 mgCO2-Cg-1MBCday-1 and the lowest was found in Medicago sativa cultivation lands equals to 0.013 mgCO2-Cg-1MBCday-1. Soil microbial indices are sensitive to land use changes. The first top 10 cm of the soil studied, has been most affected by these indices.
Due to the failure of soil pedons, the change in land use from rangeland to agricultural lands increases the speed of litter decomposition and decreases the storage of soil nutrients, the microbial population, composition and activity of the soil as an indicator of soil quality, health and fertility. But techniques of no-tillage or minimal-tillage, as well as the principles of sustainable agriculture (such as returning the residues to the soil, proper use of chemical fertilizers, using biological fertilizers, and biological control of pests) cause the destructive process of the biological indices to be adjusted and get balanced in a shorter time period with environment. Considering the changes in the biological indicators of the soil, which have caused the destruction of the cultivated lands in the studied area, it is suggested to rehabilitate the bare lands with native rangeland species of the region, such as Artemisia sieberi Besser, Zygophyllum eurypterum Boiss. & Buhse, and Astragalus tribuloides Delile. Range management plans are the only way to allocate rangelands in the region, and a detailed survey of rangelands in the region is necessary. To prevent land use change, it is important to address the multi-purpose uses of rangelands and the determination of economic units to support the lives of beneficiary households.
Introduction Marl formations are one of the most important sources of sediment production in arid and semi-arid regions. Marl lands are highly susceptible to erosion, causing an increase in drinking water treatment costs, reducing the... more
Introduction
Marl formations are one of the most important sources of sediment production in arid and semi-arid regions. Marl lands are highly susceptible to erosion, causing an increase in drinking water treatment costs, reducing the useful life of dams, and significantly decreasing the permeability of floodwater spreading areas. Different forms of erosion have been shown to have a relationship with the geological characteristics of marls, as evidenced by research. The results of the study of the effect of the physical and chemical properties of marl sediments on erosion in Latshore-Pakdasht showed that the amount of Na+, SO4-2 and silt in the marl lands increased, while the percentage of clay decreased from surface to gully erosion. The form and intensity of water erosion are greatly influenced by changes in soil texture. Gully erosion can be developed by increasing the amount of sand compared to the finer particles of silt and clay. Despite the difficulty of vegetation establishment on marl lands, in some areas, surprisingly, a relatively dense cover of rangeland species can be observed, which can cause erosion control and soil stability. The results of the systematic survey of plant species and their protective role in the marl lands of Ilam, Yazd and Gilan provinces all indicate that rangeland species are one of the most effective and suitable methods to prevent soil erosion by creating a stable vegetation cover on marl formations. The relationship between the physical and chemical properties of the soil with vegetation characteristics including distribution, canopy cover and density is inevitable. In the marl lands of Borujen, the research revealed that vegetation type named Astragalus brachycalyx-Daphne mucronata-Cirsium bracteosum can be established in neutral marl lands, with medium CaCO3 content and minimal presence of Na+ and Cl-. On the other hand, the vegetation type named Astragalus susianus-Daphne mucronata-Amygdalus elaeagnifolia can be established in alkaline and calcareous marl lands with very high amounts of Cl- and can be effective in controlling water erosion in marl lands. Considering arid and desert climate and the occurrence of surface, rill and gully erosions in the marl lands of Kashan region, as well as the importance of protecting and controlling erosion in the marl formations of the region and the lack of detailed vegetation studies
in this region, accurate identification of the vegetation of the marl lands and prioritizing native and resistant plant species is necessary for the rehabilitation management of vegetation and biological protection of soil in these areas. Therefore, the aim of the current research is to identify rangeland species and investigate their role in erosion control in the selected marl formations in Kashan. In addition, the physical and chemical soil parameters of marl lands and the vegetation characteristics of plant species in different types of erosion are investigated.
Material and Methods
Kashan is one of the marl regions chosen for the current study on the classification and determination of marl erodibility indices in Isfahan province. Two vegetation types named Anabasis setifera-Artemisia sieberi-Salsola tomentosa and Pteropyrum aucheri-Pteropyrum olivieri-Artemisia sieberi have been identified in the selected Marl lands of Kashan. In order to evaluate the erosion condition in three erosion forms of surface, rill and gully, BLM (Bureau of Land Management) form was completed in the same marl units and control areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. The physical and chemical soil properties including texture, EC, N, P, SAR, OC, CEC, CaSO4 and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, three 100 m transects were established in a random-systematic method. In each transect 10 plots of 2 m2 were placed and vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software, and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was done by SPSS statistical software.
Results and Discussion
The results showed that in terms of erodibility, Marl lands with vegetation cover had a better condition than those without vegetation. Based on analysis of variance, the physical and chemical parameters of soil and vegetation characteristics in three types of erosion had significant differences at level of 1% and 5%. In gully erosion, the amount of N, P, SAR, OC, litter and canopy cover were in better conditions compared to other types of erosion. The results of correlation between soil properties and vegetation characteristics showed that the canopy cover had significant correlation with the percentage of sand (r=0.92) and a negative correlation with the amount of CaCO3 at (r=0.97). In terms of the type of dominant plant species, in surface erosion Ephedra strobilacea Bunge. with canopy cover of 1.71%, in rill erosion Anabaisis setifera Moq. with canopy cover of 1.24% and in gully erosion Artemisia sieberi Besser. with canopy cover of 12.3% were identified as the most suitable species for soil protection. In all three types of erosion, bushes had the highest percentage of density in terms of growth form. In surface erosion and gully erosion, shrubs occupied the highest percentage of canopy cover. In gully erosion, due to better conditions of soil moisture and organic matter, bushes and shrubs were successful in competition with annual and herbaceous plants. They established well due to deep and extensive root system. The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.
Marl formations are one of the most important sources of sediment production in arid and semi-arid regions. Marl lands are highly susceptible to erosion, causing an increase in drinking water treatment costs, reducing the useful life of dams, and significantly decreasing the permeability of floodwater spreading areas. Different forms of erosion have been shown to have a relationship with the geological characteristics of marls, as evidenced by research. The results of the study of the effect of the physical and chemical properties of marl sediments on erosion in Latshore-Pakdasht showed that the amount of Na+, SO4-2 and silt in the marl lands increased, while the percentage of clay decreased from surface to gully erosion. The form and intensity of water erosion are greatly influenced by changes in soil texture. Gully erosion can be developed by increasing the amount of sand compared to the finer particles of silt and clay. Despite the difficulty of vegetation establishment on marl lands, in some areas, surprisingly, a relatively dense cover of rangeland species can be observed, which can cause erosion control and soil stability. The results of the systematic survey of plant species and their protective role in the marl lands of Ilam, Yazd and Gilan provinces all indicate that rangeland species are one of the most effective and suitable methods to prevent soil erosion by creating a stable vegetation cover on marl formations. The relationship between the physical and chemical properties of the soil with vegetation characteristics including distribution, canopy cover and density is inevitable. In the marl lands of Borujen, the research revealed that vegetation type named Astragalus brachycalyx-Daphne mucronata-Cirsium bracteosum can be established in neutral marl lands, with medium CaCO3 content and minimal presence of Na+ and Cl-. On the other hand, the vegetation type named Astragalus susianus-Daphne mucronata-Amygdalus elaeagnifolia can be established in alkaline and calcareous marl lands with very high amounts of Cl- and can be effective in controlling water erosion in marl lands. Considering arid and desert climate and the occurrence of surface, rill and gully erosions in the marl lands of Kashan region, as well as the importance of protecting and controlling erosion in the marl formations of the region and the lack of detailed vegetation studies
in this region, accurate identification of the vegetation of the marl lands and prioritizing native and resistant plant species is necessary for the rehabilitation management of vegetation and biological protection of soil in these areas. Therefore, the aim of the current research is to identify rangeland species and investigate their role in erosion control in the selected marl formations in Kashan. In addition, the physical and chemical soil parameters of marl lands and the vegetation characteristics of plant species in different types of erosion are investigated.
Material and Methods
Kashan is one of the marl regions chosen for the current study on the classification and determination of marl erodibility indices in Isfahan province. Two vegetation types named Anabasis setifera-Artemisia sieberi-Salsola tomentosa and Pteropyrum aucheri-Pteropyrum olivieri-Artemisia sieberi have been identified in the selected Marl lands of Kashan. In order to evaluate the erosion condition in three erosion forms of surface, rill and gully, BLM (Bureau of Land Management) form was completed in the same marl units and control areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. The physical and chemical soil properties including texture, EC, N, P, SAR, OC, CEC, CaSO4 and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, three 100 m transects were established in a random-systematic method. In each transect 10 plots of 2 m2 were placed and vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software, and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was done by SPSS statistical software.
Results and Discussion
The results showed that in terms of erodibility, Marl lands with vegetation cover had a better condition than those without vegetation. Based on analysis of variance, the physical and chemical parameters of soil and vegetation characteristics in three types of erosion had significant differences at level of 1% and 5%. In gully erosion, the amount of N, P, SAR, OC, litter and canopy cover were in better conditions compared to other types of erosion. The results of correlation between soil properties and vegetation characteristics showed that the canopy cover had significant correlation with the percentage of sand (r=0.92) and a negative correlation with the amount of CaCO3 at (r=0.97). In terms of the type of dominant plant species, in surface erosion Ephedra strobilacea Bunge. with canopy cover of 1.71%, in rill erosion Anabaisis setifera Moq. with canopy cover of 1.24% and in gully erosion Artemisia sieberi Besser. with canopy cover of 12.3% were identified as the most suitable species for soil protection. In all three types of erosion, bushes had the highest percentage of density in terms of growth form. In surface erosion and gully erosion, shrubs occupied the highest percentage of canopy cover. In gully erosion, due to better conditions of soil moisture and organic matter, bushes and shrubs were successful in competition with annual and herbaceous plants. They established well due to deep and extensive root system. The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.
Introduction Sand covers around 20% of the world's drylands, and 97% of it is found in the sandy land of the arid region of the earth. Different landforms are created by the wind in these regions. Sand dunes are a landform that is... more
Introduction
Sand covers around 20% of the world's drylands, and 97% of it is found in the sandy land of the arid region of the earth. Different landforms are created by the wind in these regions. Sand dunes are a landform that is mentioned in arid lands. Knowing the distribution of sand in these areas is crucial because wind erosion can cause a lot of damage. The significance of studying sand dunes lies in its impact on water and soil resources, plants and animals, human infrastructure, and roads. In Iran, various researchers and related organizations have reported various areas of the sand dunes. Different tools and methods have been utilized by these researchers, including aerial photos, topographic maps, satellite images, and field visits. This study was conducted to improve accuracy and update the existing maps due to the differences between the maps provided by previous researchers. By providing a new map of sand dunes distribution in Iran, more precise information can be obtained. Precipitation, temperature, evapotranspiration, and UNEP aridity index were used to calculate climate characteristics for Iran's sand dunes.
Material and Methods
Remote sensing was used to export the sand dunes distribution map in this research using the Google earth engine system. The image collection of the OLI sensor of the Landsat 8 satellite was used. The process of image classification involved introducing 4000 points as training points. The land use map of Iran was exported after verifying and calculating the overall accuracy and kappa coefficient, which were 0.91 and 0.89, respectively. The map's sand dune class was imported into ArcMap. The maps of the distribution of sand dunes obtained from previous researchers were compared with the obtained map. The boundary of sand dunes was modified by drawing 1020 polygons using vision recognition. We aim was always to utilize the most up-to-date satellite
images for visual interpretation. Due to differences in tools and study time, and the prepared maps based on different criteria, there are numerous differences between the maps in practice. The research utilized up-to-date satellite images and geological maps, topography, hand-planted forests, residential lands, agricultural lands, and land use as auxiliary maps. In the next step, the long-term climate maps prepared by Jamab's consulting engineers for the period of 1350 to 1390 were used to investigate climate characteristics such as temperature, precipitation, evaporation and transpiration and UNEP aridity index. The mentioned maps were interpolated and classified in ArcMap for this purpose. The distribution of the country's sand dunes was examined in each of the categories mentioned in the climatic indicators.
Results and Discussion
Based on the result, the updated area of Iran's sand dunes is 5.15 mha which includes the sand sheets and different forms of sand dunes such as barchans, star dunes and nebkas. Based on this, the provinces of Kerman, Sistan and Baluchistan, Isfahan, South Khorasan and Yazd respectively, with an area of about 1000000, 700000 and 590000 ha, have allocated the largest area of sand dunes in the country. There are some differences in the obtained results compared to the previous maps of sand dunes. In Dehlran city in Ilam province, some regions that were previously considered sand dunes have now become agricultural lands, for instance. The border modification resulted in a 366% increase in the area of Qaen city in South Khorasan province. According to climate data, sand dunes are distributed in three climates that are hyper- arid, arid, and semi-arid. The highest and lowest amount of precipitation can be found in Farashband city in Fars province and Hirmand city in Sistan and Baluchestan Province, respectively. The range of precipitation changes is ranging from 6 to 312 mm. The hottest sand dunes are located in Shahrud city in Semnan province and the coldest sand dunes are located in Buin Zahra city in Qazvin Province. The temperature of sand dunes is in the ranges of 10 to 28.5 °C. the dominant thermal regime of sand dunes is thermic, which covers about 68% of the sand dunes in 8 provinces. Hyperthermic thermal regime dominates 31% of sand dunes in 7 provinces. Only about 1% of sand dunes have mesic thermal regime which are scattered in 3 provinces. The range of changes in evapotranspiration in the sand dunes of Iran is between 1500 to 4000 mm per year. Evaluating the UNEP aridity index showed that 89% of the sand seas are classified as hyper arid and 11% of them is in arid class. The result of this research by determining the location of sand seas and their climate classification, will help the administrators to locate appropriate areas for reclamation and wind erosion control projects, especially the biological project.
Sand covers around 20% of the world's drylands, and 97% of it is found in the sandy land of the arid region of the earth. Different landforms are created by the wind in these regions. Sand dunes are a landform that is mentioned in arid lands. Knowing the distribution of sand in these areas is crucial because wind erosion can cause a lot of damage. The significance of studying sand dunes lies in its impact on water and soil resources, plants and animals, human infrastructure, and roads. In Iran, various researchers and related organizations have reported various areas of the sand dunes. Different tools and methods have been utilized by these researchers, including aerial photos, topographic maps, satellite images, and field visits. This study was conducted to improve accuracy and update the existing maps due to the differences between the maps provided by previous researchers. By providing a new map of sand dunes distribution in Iran, more precise information can be obtained. Precipitation, temperature, evapotranspiration, and UNEP aridity index were used to calculate climate characteristics for Iran's sand dunes.
Material and Methods
Remote sensing was used to export the sand dunes distribution map in this research using the Google earth engine system. The image collection of the OLI sensor of the Landsat 8 satellite was used. The process of image classification involved introducing 4000 points as training points. The land use map of Iran was exported after verifying and calculating the overall accuracy and kappa coefficient, which were 0.91 and 0.89, respectively. The map's sand dune class was imported into ArcMap. The maps of the distribution of sand dunes obtained from previous researchers were compared with the obtained map. The boundary of sand dunes was modified by drawing 1020 polygons using vision recognition. We aim was always to utilize the most up-to-date satellite
images for visual interpretation. Due to differences in tools and study time, and the prepared maps based on different criteria, there are numerous differences between the maps in practice. The research utilized up-to-date satellite images and geological maps, topography, hand-planted forests, residential lands, agricultural lands, and land use as auxiliary maps. In the next step, the long-term climate maps prepared by Jamab's consulting engineers for the period of 1350 to 1390 were used to investigate climate characteristics such as temperature, precipitation, evaporation and transpiration and UNEP aridity index. The mentioned maps were interpolated and classified in ArcMap for this purpose. The distribution of the country's sand dunes was examined in each of the categories mentioned in the climatic indicators.
Results and Discussion
Based on the result, the updated area of Iran's sand dunes is 5.15 mha which includes the sand sheets and different forms of sand dunes such as barchans, star dunes and nebkas. Based on this, the provinces of Kerman, Sistan and Baluchistan, Isfahan, South Khorasan and Yazd respectively, with an area of about 1000000, 700000 and 590000 ha, have allocated the largest area of sand dunes in the country. There are some differences in the obtained results compared to the previous maps of sand dunes. In Dehlran city in Ilam province, some regions that were previously considered sand dunes have now become agricultural lands, for instance. The border modification resulted in a 366% increase in the area of Qaen city in South Khorasan province. According to climate data, sand dunes are distributed in three climates that are hyper- arid, arid, and semi-arid. The highest and lowest amount of precipitation can be found in Farashband city in Fars province and Hirmand city in Sistan and Baluchestan Province, respectively. The range of precipitation changes is ranging from 6 to 312 mm. The hottest sand dunes are located in Shahrud city in Semnan province and the coldest sand dunes are located in Buin Zahra city in Qazvin Province. The temperature of sand dunes is in the ranges of 10 to 28.5 °C. the dominant thermal regime of sand dunes is thermic, which covers about 68% of the sand dunes in 8 provinces. Hyperthermic thermal regime dominates 31% of sand dunes in 7 provinces. Only about 1% of sand dunes have mesic thermal regime which are scattered in 3 provinces. The range of changes in evapotranspiration in the sand dunes of Iran is between 1500 to 4000 mm per year. Evaluating the UNEP aridity index showed that 89% of the sand seas are classified as hyper arid and 11% of them is in arid class. The result of this research by determining the location of sand seas and their climate classification, will help the administrators to locate appropriate areas for reclamation and wind erosion control projects, especially the biological project.
Research Interests:
Introduction Groundwater is the main source of fresh water in arid and semi-arid regions, making it resilient to the lack of precipitation. Previously, groundwater was considered an unlimited or, at a minimum, entirely renewable natural... more
Introduction
Groundwater is the main source of fresh water in arid and semi-arid regions, making it resilient to the lack of precipitation. Previously, groundwater was considered an unlimited or, at a minimum, entirely renewable natural resource. However, in recent decades, primarily because of population growth and industrial development, it has been under irreparable pressure, which has resulted in groundwater depletion in most parts of the world, in particular in Iran. In addition to the mentioned factors, climatic events, climatic changes caused by global warming and drought sequences, geological and topographical characteristics are also effective at raising and lowering ground water levels. Several studies have been conducted to investigate factors affecting the depletion of aquifers. Studies such as the investigation of climatic factors and aquifer extraction on changes in the level of the Maharluo lake, changes in groundwater quantity and quality in Sistan and Balochistan and factors affecting the depletion of aquifer storage in Darab have shown that the human and climatic factors have been effective in depleting groundwater. Studies in China have stated that socio-economic and agricultural development, land use changes, and dam construction are the most important factors in depleting groundwater resources. The Minab Plain is one of the fertile areas of Hormozgan province, where excessive groundwater extraction has reduced groundwater levels in the area. This plain also plays an important part in the transfer of water between basins from Minab to Bandar Abbas, so that a large quantity of water is pumped and transferred daily. Therefore, it is important to study the variables that affect the depletion of groundwater reserves in this plain. Considerable research has been carried out in the Minab plain to investigate changes in hydroclimatic variables, land use and groundwater. However, no research was conducted on the effect of these factors on groundwater loss. The aim of this research is to analyze the trend of hydro-climatic variables and groundwater level, to investigate land use changes, to detect the trend of groundwater extraction, water transfer operations from Minab plain to Bandar Abbas and, to investigate its effects on depletion in the Minab plain.
Material and Methods
The study area in the present study is the Minab Plain which the Esteghlal Dam was built on this river in 1983, with a water intake volume of 250 MCM. The data used in the research including the groundwater level, precipitation, discharge, and temperature. The number of 47 piezometric or observation wells have measured water level variations in the Minab plain since 1986, and 20 rain gauge stations have been distributed around case studies, of which 10 active rain gauge stations, six evapotranspiration stations and four hydrometer stations are used with a long statistical period. In the current study, the Mann-Kendall non-parametric method was used to analyze the trend. The point change was determined by the Pettitt’s test. Landsat satellite time series images were used to extract land use classes. Considering the existing land uses in the region, five land uses were considered: agricultural, rock, rangeland, urban and waterbodies. The images were analyzed in three time periods of 1991, 2005 and 2021 using Landsat satellite images.
Results and Discussion
The results indicate that during the 1986-2020 statistical period, the average level of groundwater in the plain fell by 10.19 m. The calculated Mann-Kendall statistic is -6.69, indicating a significant negative trend and, according to the Pettitt test statistics, 2013 was reported as a time of change. With respect to the trend of hydroclimatic variables, temperature and evapotranspiration are increasing at all stations, while precipitation and flow are trending downward which is not statistically significant. In addition, at most stations, change points were from 2001. The results of the land use change survey showed that rangeland decreased by 22%, and irrigated agricultural land and urban land increased by 2.2 and 2.8 times, respectively. In investigating the effect of human factors on groundwater depletion levels, it showed that the number of wells increased from about 100 to 796 wells, 16 wells were drilled in this plain to provide drinking water to Bandar Abbas, and the inter-basin water transfer with a discharge flow of 1200 lit/s, started since 2002 has put double pressure on the storage. The other reason for groundwater depletion is the decrease in aquifer feeding because of the decrease in precipitation, increase in temperature and evaporation, and decrease in infiltration of water from the Minab River, especially after the operation of Esteghlal dam in 1984. The amount of aquifer feed due to runoff infiltration is 12/77 MCM, or 22% of the total aquifer feed. Finally, it can be concluded that natural factors, including a reduction in precipitation and runoff and an increase in temperature, and non-natural factors such as building dams, increasing the allocation of aquifers for agriculture, domestic and industrial purposes, inter-basin transfer water, the increase in agricultural land and residential areas led to a double pressure on groundwater storage in the Minab Plain, resulting in a marked depletion of groundwater levels in the Minab Plain.
Groundwater is the main source of fresh water in arid and semi-arid regions, making it resilient to the lack of precipitation. Previously, groundwater was considered an unlimited or, at a minimum, entirely renewable natural resource. However, in recent decades, primarily because of population growth and industrial development, it has been under irreparable pressure, which has resulted in groundwater depletion in most parts of the world, in particular in Iran. In addition to the mentioned factors, climatic events, climatic changes caused by global warming and drought sequences, geological and topographical characteristics are also effective at raising and lowering ground water levels. Several studies have been conducted to investigate factors affecting the depletion of aquifers. Studies such as the investigation of climatic factors and aquifer extraction on changes in the level of the Maharluo lake, changes in groundwater quantity and quality in Sistan and Balochistan and factors affecting the depletion of aquifer storage in Darab have shown that the human and climatic factors have been effective in depleting groundwater. Studies in China have stated that socio-economic and agricultural development, land use changes, and dam construction are the most important factors in depleting groundwater resources. The Minab Plain is one of the fertile areas of Hormozgan province, where excessive groundwater extraction has reduced groundwater levels in the area. This plain also plays an important part in the transfer of water between basins from Minab to Bandar Abbas, so that a large quantity of water is pumped and transferred daily. Therefore, it is important to study the variables that affect the depletion of groundwater reserves in this plain. Considerable research has been carried out in the Minab plain to investigate changes in hydroclimatic variables, land use and groundwater. However, no research was conducted on the effect of these factors on groundwater loss. The aim of this research is to analyze the trend of hydro-climatic variables and groundwater level, to investigate land use changes, to detect the trend of groundwater extraction, water transfer operations from Minab plain to Bandar Abbas and, to investigate its effects on depletion in the Minab plain.
Material and Methods
The study area in the present study is the Minab Plain which the Esteghlal Dam was built on this river in 1983, with a water intake volume of 250 MCM. The data used in the research including the groundwater level, precipitation, discharge, and temperature. The number of 47 piezometric or observation wells have measured water level variations in the Minab plain since 1986, and 20 rain gauge stations have been distributed around case studies, of which 10 active rain gauge stations, six evapotranspiration stations and four hydrometer stations are used with a long statistical period. In the current study, the Mann-Kendall non-parametric method was used to analyze the trend. The point change was determined by the Pettitt’s test. Landsat satellite time series images were used to extract land use classes. Considering the existing land uses in the region, five land uses were considered: agricultural, rock, rangeland, urban and waterbodies. The images were analyzed in three time periods of 1991, 2005 and 2021 using Landsat satellite images.
Results and Discussion
The results indicate that during the 1986-2020 statistical period, the average level of groundwater in the plain fell by 10.19 m. The calculated Mann-Kendall statistic is -6.69, indicating a significant negative trend and, according to the Pettitt test statistics, 2013 was reported as a time of change. With respect to the trend of hydroclimatic variables, temperature and evapotranspiration are increasing at all stations, while precipitation and flow are trending downward which is not statistically significant. In addition, at most stations, change points were from 2001. The results of the land use change survey showed that rangeland decreased by 22%, and irrigated agricultural land and urban land increased by 2.2 and 2.8 times, respectively. In investigating the effect of human factors on groundwater depletion levels, it showed that the number of wells increased from about 100 to 796 wells, 16 wells were drilled in this plain to provide drinking water to Bandar Abbas, and the inter-basin water transfer with a discharge flow of 1200 lit/s, started since 2002 has put double pressure on the storage. The other reason for groundwater depletion is the decrease in aquifer feeding because of the decrease in precipitation, increase in temperature and evaporation, and decrease in infiltration of water from the Minab River, especially after the operation of Esteghlal dam in 1984. The amount of aquifer feed due to runoff infiltration is 12/77 MCM, or 22% of the total aquifer feed. Finally, it can be concluded that natural factors, including a reduction in precipitation and runoff and an increase in temperature, and non-natural factors such as building dams, increasing the allocation of aquifers for agriculture, domestic and industrial purposes, inter-basin transfer water, the increase in agricultural land and residential areas led to a double pressure on groundwater storage in the Minab Plain, resulting in a marked depletion of groundwater levels in the Minab Plain.
Introduction Over the past 60 years, the use of plastic covers as a tool to increase the harvest and increase the yield of horticultural crops has steadily increased worldwide. Plastic greenhouses have turned desert areas into areas with... more
Introduction
Over the past 60 years, the use of plastic covers as a tool to increase the harvest and increase the yield of horticultural crops has steadily increased worldwide. Plastic greenhouses have turned desert areas into areas with modern agricultural development, the province of Almera in the south of Spain is a good example. It now has many greenhouses, making it a global model of agricultural development; but greenhouses contain large quantities of phthalates and cause harm to people, like hormonal disturbances, heart problems, cancer, etc. However, plastic greenhouses are widely built to produce vegetables and fruits near cities. As a result, several remote sensing methods have been developed to identify and monitor the distribution of plastic covered greenhouses in order to manage water resources, identify sites and quantities of plastic greenhouses. Remote detection is the only practical method to monitor plastic greenhouses in a vast geographic area. In the past few years, there have been few studies using high spatial resolution images. In one study, three main absorption ranges were identified that are unaffected by dust, washing and surface factors. In Spain, an artificial intelligence neural network has been proposed to identify greenhouse using Quick Bird images with a resolution of 1.5m. Studies based on medium spatial resolution imagery were also conducted, resulting in different results. In search on land cover classification using Landsat TM images, no favorable results were found. Research has proposed a new method for mapping greenhouses using Sentinel-2 dual-time images and 1D-CNN deep learning. The aim of the current research is to identify the length of the cultivation period of greenhouse crops using Sentinel-2 satellite images. Researchers used a variety of satellite imagery to identify and classify greenhouses. The innovative objective of the current research is to evaluate the Sentinel-2 satellite images in determining the length of the cultivation period of greenhouse crops; which was done for the first time within the country.
Material and Methods
In the first step, the cultivated area of greenhouses was identified using an aerial photograph. Then, useful bands were extracted in greenhouse studies using Sentinel-2 time series images. Next, vegetation and plastic cover indices were calculated for the greenhouse growing period.
1) Identify and determine the area under cultivation in greenhouses: By comparing the pixel-based classification algorithms and the object-oriented classification algorithms, the cultivated area of greenhouses was identified. ENVI and eCognition software were used for pixel-based classification and object-oriented classification, respectively. It should be noted that only one aerial photograph with three bands, blue, green and red, has been used in object-oriented classification. In order to classify the base pixel, learning samples were selected using expert knowledge from the study area. In some instances, Google Earth was used as well. Learning samples were selected scattered across the image to improve accuracy. For validation of the maps obtained from these algorithms, ground control points were used. To reduce human error, these points were also entered into Google Earth. 2) Identifying functional bands in the greenhouse study: The spectral behavior curve of different earth surface covers in Blue, Green, Red, SWIR, NIR bands was drawn in an image of the Sentinel-2 satellite. These spectral signatures were compared on May 20, 2020 i.e., when outdoor vegetation and greenhouse cultivation were at their peak. 3) Determining the duration of the greenhouse growing season: Vegetation indices of the NDVI, SAVI, OSAVI, MSAVI, GNDVI, RVI, DVI, RGVI, IPVI and plastic cover indices PGI, RPGI, PI, PMLI were compared using Sentinel-2 satellite time series images.
Results and Discussion
Greenhouse cultivation is used to improve quality and increase food production. However, their development has many negative effects on the environment. Therefore, obtaining accurate and timely information on the distribution of greenhouses and the time of planting and harvesting crops under plastic covers can make a significant contribution to agricultural management, water management and soil protection. The present study is the first study to identify the length of the greenhouse cultivation period using Sentinel-2 satellite time series images. The results showed that among the object-oriented classification algorithms, two classification algorithms, Bayes and KNN, were more precise for the identification and determination of the cultivated area of greenhouses. The reflection of the plant below the plastic cover of the greenhouse in the NIR, Narrow NIR, Red Edge and SWIR bands increases by an equal amount in comparison with the reflection from the vegetation in the open space. Comparing vegetation cover and greenhouse cover indices showed that the indices designed based on SWIR and Red bands showed greater reflection during the hot season of the year. Indices based on NIR, Narrow NIR, and Red Edge bands were more reflective from October to late February. Based on the results obtained from the ground truth data, greenhouses are plastered during the warm season. This caused an increase in the reflectance in indices designed based on SWIR and Red bands and a decrease in reflectance in indices designed based on NIR, Narrow NIR, Red Edge bands, during the hot season. Therefore, combining all indices, two crop periods were observed: the first started in early March, peak cover was reached in April, and harvest continued. Until the middle of August. The second harvest started at the end of August and peaked in December, until the end of harvest in mid-February.
Over the past 60 years, the use of plastic covers as a tool to increase the harvest and increase the yield of horticultural crops has steadily increased worldwide. Plastic greenhouses have turned desert areas into areas with modern agricultural development, the province of Almera in the south of Spain is a good example. It now has many greenhouses, making it a global model of agricultural development; but greenhouses contain large quantities of phthalates and cause harm to people, like hormonal disturbances, heart problems, cancer, etc. However, plastic greenhouses are widely built to produce vegetables and fruits near cities. As a result, several remote sensing methods have been developed to identify and monitor the distribution of plastic covered greenhouses in order to manage water resources, identify sites and quantities of plastic greenhouses. Remote detection is the only practical method to monitor plastic greenhouses in a vast geographic area. In the past few years, there have been few studies using high spatial resolution images. In one study, three main absorption ranges were identified that are unaffected by dust, washing and surface factors. In Spain, an artificial intelligence neural network has been proposed to identify greenhouse using Quick Bird images with a resolution of 1.5m. Studies based on medium spatial resolution imagery were also conducted, resulting in different results. In search on land cover classification using Landsat TM images, no favorable results were found. Research has proposed a new method for mapping greenhouses using Sentinel-2 dual-time images and 1D-CNN deep learning. The aim of the current research is to identify the length of the cultivation period of greenhouse crops using Sentinel-2 satellite images. Researchers used a variety of satellite imagery to identify and classify greenhouses. The innovative objective of the current research is to evaluate the Sentinel-2 satellite images in determining the length of the cultivation period of greenhouse crops; which was done for the first time within the country.
Material and Methods
In the first step, the cultivated area of greenhouses was identified using an aerial photograph. Then, useful bands were extracted in greenhouse studies using Sentinel-2 time series images. Next, vegetation and plastic cover indices were calculated for the greenhouse growing period.
1) Identify and determine the area under cultivation in greenhouses: By comparing the pixel-based classification algorithms and the object-oriented classification algorithms, the cultivated area of greenhouses was identified. ENVI and eCognition software were used for pixel-based classification and object-oriented classification, respectively. It should be noted that only one aerial photograph with three bands, blue, green and red, has been used in object-oriented classification. In order to classify the base pixel, learning samples were selected using expert knowledge from the study area. In some instances, Google Earth was used as well. Learning samples were selected scattered across the image to improve accuracy. For validation of the maps obtained from these algorithms, ground control points were used. To reduce human error, these points were also entered into Google Earth. 2) Identifying functional bands in the greenhouse study: The spectral behavior curve of different earth surface covers in Blue, Green, Red, SWIR, NIR bands was drawn in an image of the Sentinel-2 satellite. These spectral signatures were compared on May 20, 2020 i.e., when outdoor vegetation and greenhouse cultivation were at their peak. 3) Determining the duration of the greenhouse growing season: Vegetation indices of the NDVI, SAVI, OSAVI, MSAVI, GNDVI, RVI, DVI, RGVI, IPVI and plastic cover indices PGI, RPGI, PI, PMLI were compared using Sentinel-2 satellite time series images.
Results and Discussion
Greenhouse cultivation is used to improve quality and increase food production. However, their development has many negative effects on the environment. Therefore, obtaining accurate and timely information on the distribution of greenhouses and the time of planting and harvesting crops under plastic covers can make a significant contribution to agricultural management, water management and soil protection. The present study is the first study to identify the length of the greenhouse cultivation period using Sentinel-2 satellite time series images. The results showed that among the object-oriented classification algorithms, two classification algorithms, Bayes and KNN, were more precise for the identification and determination of the cultivated area of greenhouses. The reflection of the plant below the plastic cover of the greenhouse in the NIR, Narrow NIR, Red Edge and SWIR bands increases by an equal amount in comparison with the reflection from the vegetation in the open space. Comparing vegetation cover and greenhouse cover indices showed that the indices designed based on SWIR and Red bands showed greater reflection during the hot season of the year. Indices based on NIR, Narrow NIR, and Red Edge bands were more reflective from October to late February. Based on the results obtained from the ground truth data, greenhouses are plastered during the warm season. This caused an increase in the reflectance in indices designed based on SWIR and Red bands and a decrease in reflectance in indices designed based on NIR, Narrow NIR, Red Edge bands, during the hot season. Therefore, combining all indices, two crop periods were observed: the first started in early March, peak cover was reached in April, and harvest continued. Until the middle of August. The second harvest started at the end of August and peaked in December, until the end of harvest in mid-February.
Introduction Today, one of the biggest challenges for mankind is the lack of water resources in the world. This is one of the limiting factors for agricultural development in Iran in recent years. Identifying and estimating reference... more
Introduction
Today, one of the biggest challenges for mankind is the lack of water resources in the world. This is one of the limiting factors for agricultural development in Iran in recent years. Identifying and estimating reference evapotranspiration (ET0) can help make decisions to plan and mitigate the use of water resources and appropriate management methods in the country. Thus, one of the ways to reduce water losses in the fields is good irrigation planning, which is based on accurate estimation of the water requirements of plants and ET0. The aim of this research is to evaluate the ET0 changes using temperature and radiation methods, statistical tests such as Man-Kendall, Sen’s slope analysis in Iran over the last decades.
Material and Methods
In the current research, primary evaluation of data, such as sorting, etc., was conducted in the desired ET0 calculation format. For the classification of weather station climate, annual precipitation and temperature data from 1976 to 2020 were used. To estimate ET0, maximum temperature (°C), minimum temperature (°C), average relative humidity (%), wind speed (m/s), and sunshine hour (h) were used on a monthly time scale. The Koppen-Geiger climate classification method was used to classify the meteorological stations studied. For estimating monthly and annual ET0, the methods such as FAO Penman-Monteith (FAO PM), Hargreaves-Samani (H-S), and Priestley Taylor (PT) were used. Then, an attempt was made to introduce the appropriate model for each climate by using the results of ET0 estimation using RMSE and MAE. ET0 maps were produced with more accuracy based on the results of the RMSE. Among different geostatistical interpolation methods, the Kriging method worked better than the other methods, which was used as the superior interpolation method. The Mann-Kendall non-parametric test was used to detect the trend of time series. To examine the trend slope in the ET0 time series, the
non-parametric Sen's slope method was used. For qualitative analysis of the ET0 trend, the innovative ITA trend was used for all three methods on a yearly basis
Results and Discussion
In this research, the station climate classification results show that climate varieties in Iran are high and can be divided into seven different climates. According to the RMSE and MAE statistical evaluations, the H-S method in semi-desert climates, dry and cold steppe, dry desert, temperate with dry summers, very hot semi-desert and snowy climates; and PT method in dry desert climates, moderate with dry summers, semi-desert, and very hot semi-desert were recognized as superior methods. In the temperate and rainy climate zone of Bandar Anzali, the H-S, and in Rasht, the PT methods were evaluated as suitable methods. Based on the monthly ET0 estimation, the amount of ET0 is significantly reduced in the northwestern, western and northeastern regions during the winter season. In winter, ET0 decreases as a result of increased air moisture. In the spring season, the amount of ET0 declined in the northern latitudes. The onset of convective spring rains in the northern latitudes of the country is one of the reasons behind this reduction in ET0 in these areas. During the summer season, regions in the upper latitudes have a lower ET0 because of their lower temperature than southern latitudes. In the autumn, there is a lower ET0 in the northern latitudes than in the southern regions of the country. Trend analysis shows that with the exception of the Arak station with an ET0 downward trend in April, most ET0 time series have a positive trend in the rest of the stations. Sanandaj is the only station that has a downward trend in ET0 in November. An increasing trend is observed in most of the studied stations, but in some other stations such as Arak and Sanandaj, a downward trend in the Reference Evapotranspiration may be observed. Finally, the results of the Innovative Trend Analysis (ITA) showed an upward trend in the amount of ET0 in both high and low areas in all seasons. This shows the increase of the long-term ET0 trend, indicating the increase in water requirements for plants in Iran. In the present study, climatic data from 40 stations from 1976 to 2020 were used to estimate ET0 in Iran. The Koppen- Geiger method was also used to classify the weather stations into the seven climates classes. The FAO PM, H-S, and PT models were used to estimate monthly and annually ET0. To choose the appropriate method of estimating ET0 in each climate zones; the H-S and PT methods were compared with the FAO PM method, and validated using RMSE and MAE statistics. Due to the involvement of various processes in ET0 changes, the best estimation method differs between stations. In this research, the H-S method was more compatible than the PT method at most of the stations. Results have been presented as monthly and annual zoning maps. The zoning results of the three ET0 calculation methods mentioned showed that changes in climatic elements in different regions and periods have different effects on the ET0 value. The trend in ET0 changes using the Mann-Kendall test showed that the ET0 data at most stations have an increasing slope. Only two stations (Arak representing the top stations and Sanandaj representing the bottom station) have a decreasing slope. Based on the results of the ET0 time series analysis using ITA, the ET0 trend increased at all stations representative of the high and low elevation zones. Overall results show that TE0 has increased in most parts of the country, resulting in increased water requirements for plants. In the absence of effective management, Iran will face a serious water crisis in the future.
Today, one of the biggest challenges for mankind is the lack of water resources in the world. This is one of the limiting factors for agricultural development in Iran in recent years. Identifying and estimating reference evapotranspiration (ET0) can help make decisions to plan and mitigate the use of water resources and appropriate management methods in the country. Thus, one of the ways to reduce water losses in the fields is good irrigation planning, which is based on accurate estimation of the water requirements of plants and ET0. The aim of this research is to evaluate the ET0 changes using temperature and radiation methods, statistical tests such as Man-Kendall, Sen’s slope analysis in Iran over the last decades.
Material and Methods
In the current research, primary evaluation of data, such as sorting, etc., was conducted in the desired ET0 calculation format. For the classification of weather station climate, annual precipitation and temperature data from 1976 to 2020 were used. To estimate ET0, maximum temperature (°C), minimum temperature (°C), average relative humidity (%), wind speed (m/s), and sunshine hour (h) were used on a monthly time scale. The Koppen-Geiger climate classification method was used to classify the meteorological stations studied. For estimating monthly and annual ET0, the methods such as FAO Penman-Monteith (FAO PM), Hargreaves-Samani (H-S), and Priestley Taylor (PT) were used. Then, an attempt was made to introduce the appropriate model for each climate by using the results of ET0 estimation using RMSE and MAE. ET0 maps were produced with more accuracy based on the results of the RMSE. Among different geostatistical interpolation methods, the Kriging method worked better than the other methods, which was used as the superior interpolation method. The Mann-Kendall non-parametric test was used to detect the trend of time series. To examine the trend slope in the ET0 time series, the
non-parametric Sen's slope method was used. For qualitative analysis of the ET0 trend, the innovative ITA trend was used for all three methods on a yearly basis
Results and Discussion
In this research, the station climate classification results show that climate varieties in Iran are high and can be divided into seven different climates. According to the RMSE and MAE statistical evaluations, the H-S method in semi-desert climates, dry and cold steppe, dry desert, temperate with dry summers, very hot semi-desert and snowy climates; and PT method in dry desert climates, moderate with dry summers, semi-desert, and very hot semi-desert were recognized as superior methods. In the temperate and rainy climate zone of Bandar Anzali, the H-S, and in Rasht, the PT methods were evaluated as suitable methods. Based on the monthly ET0 estimation, the amount of ET0 is significantly reduced in the northwestern, western and northeastern regions during the winter season. In winter, ET0 decreases as a result of increased air moisture. In the spring season, the amount of ET0 declined in the northern latitudes. The onset of convective spring rains in the northern latitudes of the country is one of the reasons behind this reduction in ET0 in these areas. During the summer season, regions in the upper latitudes have a lower ET0 because of their lower temperature than southern latitudes. In the autumn, there is a lower ET0 in the northern latitudes than in the southern regions of the country. Trend analysis shows that with the exception of the Arak station with an ET0 downward trend in April, most ET0 time series have a positive trend in the rest of the stations. Sanandaj is the only station that has a downward trend in ET0 in November. An increasing trend is observed in most of the studied stations, but in some other stations such as Arak and Sanandaj, a downward trend in the Reference Evapotranspiration may be observed. Finally, the results of the Innovative Trend Analysis (ITA) showed an upward trend in the amount of ET0 in both high and low areas in all seasons. This shows the increase of the long-term ET0 trend, indicating the increase in water requirements for plants in Iran. In the present study, climatic data from 40 stations from 1976 to 2020 were used to estimate ET0 in Iran. The Koppen- Geiger method was also used to classify the weather stations into the seven climates classes. The FAO PM, H-S, and PT models were used to estimate monthly and annually ET0. To choose the appropriate method of estimating ET0 in each climate zones; the H-S and PT methods were compared with the FAO PM method, and validated using RMSE and MAE statistics. Due to the involvement of various processes in ET0 changes, the best estimation method differs between stations. In this research, the H-S method was more compatible than the PT method at most of the stations. Results have been presented as monthly and annual zoning maps. The zoning results of the three ET0 calculation methods mentioned showed that changes in climatic elements in different regions and periods have different effects on the ET0 value. The trend in ET0 changes using the Mann-Kendall test showed that the ET0 data at most stations have an increasing slope. Only two stations (Arak representing the top stations and Sanandaj representing the bottom station) have a decreasing slope. Based on the results of the ET0 time series analysis using ITA, the ET0 trend increased at all stations representative of the high and low elevation zones. Overall results show that TE0 has increased in most parts of the country, resulting in increased water requirements for plants. In the absence of effective management, Iran will face a serious water crisis in the future.
Introduction Harsh ecological conditions, including water scarcity, have limited vegetation life in desert areas. Consequently, the cultivation of drought-resistant plants compatible with desert areas and their expansion, while creating... more
Introduction
Harsh ecological conditions, including water scarcity, have limited vegetation life in desert areas. Consequently, the cultivation of drought-resistant plants compatible with desert areas and their expansion, while creating suitable vegetation, increases biodiversity, controls desertification and is oriented towards the sustainability of desert ecosystems. Cannabis is a drought-tolerant plant which, because of its great genetic diversity, has the ability to grow in different climates, particularly in semi-desert areas. Appropriate agricultural management enhances the vegetation, production and productivity of agricultural products. In this context, it is important to study planting date and plant density as factors impacting production. Planting dates must be chosen to allow sufficient time for each stage of growth and development. The use of optimal plant density may improve plant growth and increase plant yield by reducing intra-plant competition. Results of search on two densities of cannabis plants of 8 and 16 plants per m-2 in Birjand, the highest seed yield was obtained from a density of 16 plants per m-2. Finding on densities of 50, 150, and 250 plants per m-2 in Mashhad, and 30, 90, and 150 plants per m-2 in Shirvan reported that as the density of cannabis plants increased, the flowering date decreased in both regions. Given the arid and semi-arid climate of South Khorasan, planting plants compatible with the climate of the region, such as cannabis, can increase vegetation cover while producing an acceptable yield. The objectives of the current research are to study the effect of agricultural management on the growth characteristics of the forgotten cannabis plant in semi-arid climate of Birjand.
Material and Methods
The current research was carried out in Center of Agriculture and Natural Resources Research if South Khorasan, located at 59′ 13° east longitude and 53° 32′north latitude, and 1491m above sea level. South Khorasan province has a desert and semi-desert climate. Before preparing the soil to determine the required amount of chemical and organic fertilizers, the soil in the field was analyzed. Data on temperature changes and the total number of sunny hours of various months
during the cannabis growing period were received from the Birjand weather station. The experiment was conducted as a split plot based on a randomized complete block design with three replications. Treatments investigated included planting date on three levels of May 12, May 27 and June 11 as the main plot and plant density at three levels of 22.2, 11.1 and 7.4 plants per m-2 as the sub plot. In this research, the phenological characteristics including the number of days to emergency, days to flowering, days to seed filling, days to physiological maturity, length of vegetative period, length of reproductive period, length of flowering period, and morphological characteristics including plant height, number of main stem branches, stem diameter and seed yield were investigated. Statistical analysis of the data was done using SAS software and the comparison of averages was done based on Duncan's 5% multiple range test.
Results and Discussion
The results showed that the impact of planting date on all morphophenological traits was significant, with the exception of stem diameter. The delay in planting between May 12 and June 11 significantly reduced the length of phenological stages, and vegetative growth of cannabis, and ultimately caused a 48% decrease in seed yield. Late cultivation, due to the increase in temperature, the plant completes its vegetative growth faster. The delay in planting by shortening the period of effective growth, reducing the photosynthetic potential of the plant, and coinciding with the period of seed filling with low temperatures and shortening of the day has led to a decrease in the quantity and the filling speed of the seeds, and subsequently the yield of the seeds decreases. It has been reported that a 20-day delay in seeding from 10 May led to a 46% decrease in seed yield under climatic conditions in Azerbaijan. The effect of plant density on morphological traits, number of days until flowering of female plants, days until seed set, days until physiological maturity, length of vegetative period, length of flowering period and seed yield were significant. The increase in density from 7.4 to 22.2 plants per m-2, while delaying flowering, increased seed yield by 15.4%. Increased plant density due to higher plant height and increased number of plants per unit area increased seed yield. Results of search on two densities of cannabis plants of 8 and 16 plants per m-2 in Birjand, the highest seed yield was obtained from a density of 16 plants per m-2. To achieve proper yield performance, and develop cannabis cultivation- as a plant compatible with the semi-desert region- the planting date of May 12 and the density of 22.2 plants per m-2 can be used.
Harsh ecological conditions, including water scarcity, have limited vegetation life in desert areas. Consequently, the cultivation of drought-resistant plants compatible with desert areas and their expansion, while creating suitable vegetation, increases biodiversity, controls desertification and is oriented towards the sustainability of desert ecosystems. Cannabis is a drought-tolerant plant which, because of its great genetic diversity, has the ability to grow in different climates, particularly in semi-desert areas. Appropriate agricultural management enhances the vegetation, production and productivity of agricultural products. In this context, it is important to study planting date and plant density as factors impacting production. Planting dates must be chosen to allow sufficient time for each stage of growth and development. The use of optimal plant density may improve plant growth and increase plant yield by reducing intra-plant competition. Results of search on two densities of cannabis plants of 8 and 16 plants per m-2 in Birjand, the highest seed yield was obtained from a density of 16 plants per m-2. Finding on densities of 50, 150, and 250 plants per m-2 in Mashhad, and 30, 90, and 150 plants per m-2 in Shirvan reported that as the density of cannabis plants increased, the flowering date decreased in both regions. Given the arid and semi-arid climate of South Khorasan, planting plants compatible with the climate of the region, such as cannabis, can increase vegetation cover while producing an acceptable yield. The objectives of the current research are to study the effect of agricultural management on the growth characteristics of the forgotten cannabis plant in semi-arid climate of Birjand.
Material and Methods
The current research was carried out in Center of Agriculture and Natural Resources Research if South Khorasan, located at 59′ 13° east longitude and 53° 32′north latitude, and 1491m above sea level. South Khorasan province has a desert and semi-desert climate. Before preparing the soil to determine the required amount of chemical and organic fertilizers, the soil in the field was analyzed. Data on temperature changes and the total number of sunny hours of various months
during the cannabis growing period were received from the Birjand weather station. The experiment was conducted as a split plot based on a randomized complete block design with three replications. Treatments investigated included planting date on three levels of May 12, May 27 and June 11 as the main plot and plant density at three levels of 22.2, 11.1 and 7.4 plants per m-2 as the sub plot. In this research, the phenological characteristics including the number of days to emergency, days to flowering, days to seed filling, days to physiological maturity, length of vegetative period, length of reproductive period, length of flowering period, and morphological characteristics including plant height, number of main stem branches, stem diameter and seed yield were investigated. Statistical analysis of the data was done using SAS software and the comparison of averages was done based on Duncan's 5% multiple range test.
Results and Discussion
The results showed that the impact of planting date on all morphophenological traits was significant, with the exception of stem diameter. The delay in planting between May 12 and June 11 significantly reduced the length of phenological stages, and vegetative growth of cannabis, and ultimately caused a 48% decrease in seed yield. Late cultivation, due to the increase in temperature, the plant completes its vegetative growth faster. The delay in planting by shortening the period of effective growth, reducing the photosynthetic potential of the plant, and coinciding with the period of seed filling with low temperatures and shortening of the day has led to a decrease in the quantity and the filling speed of the seeds, and subsequently the yield of the seeds decreases. It has been reported that a 20-day delay in seeding from 10 May led to a 46% decrease in seed yield under climatic conditions in Azerbaijan. The effect of plant density on morphological traits, number of days until flowering of female plants, days until seed set, days until physiological maturity, length of vegetative period, length of flowering period and seed yield were significant. The increase in density from 7.4 to 22.2 plants per m-2, while delaying flowering, increased seed yield by 15.4%. Increased plant density due to higher plant height and increased number of plants per unit area increased seed yield. Results of search on two densities of cannabis plants of 8 and 16 plants per m-2 in Birjand, the highest seed yield was obtained from a density of 16 plants per m-2. To achieve proper yield performance, and develop cannabis cultivation- as a plant compatible with the semi-desert region- the planting date of May 12 and the density of 22.2 plants per m-2 can be used.
Introduction Rangeland provides numerous ecosystem goods and services. Most rangeland management decisions focus on forage production, and this can lead to the loss of other rangeland ecosystem services. One of those services is carbon... more
Introduction
Rangeland provides numerous ecosystem goods and services. Most rangeland management decisions focus on forage production, and this can lead to the loss of other rangeland ecosystem services. One of those services is carbon sequestration, the removal of carbon dioxide from the Earth's atmosphere and its storage in the ground. Rangeland, which covers approximately half of terrestrial ecosystems, is one of the most important sinks for atmospheric carbon dioxide. Photosynthesis, respiration and decomposition are the main processes in the ecosystem that determine how carbon is stored in the soil. Anthropogenic activities like livestock grazing can significantly alter soil carbon storage. Unfortunately, human activities have resulted in lower soil carbon and increased global climate change. Livestock grazing is one of the most significant factors affecting the structure and functioning of ecosystems. Grazing livestock can affect the amount of carbon in the soil through reduced vegetation cover, altered species composition, soil degradation, urination and defecation. On the other hand, changes in the quantity and quality of forage production by livestock grazing have a strong effect on the welfare of the beneficiaries. Consequently, knowledge of the relationship between forage production and other ecosystem goods and services such as soil carbon is essential to the sustainability of ecosystems. It is important to study the quantity and quality changes in rangeland production in relation to different livestock grazing intensities on soil carbon. However, this information can assist range managers in providing techniques to promote soil carbon storage. The purpose of the study is 1) to determine annual forage production in rangelands at different grazing intensities, 2) to study the quality of rangeland forages produced, 3) to assess soil carbon content at different grazing intensities, and 4) to assess the relationship between rangeland production and soil carbon content at different grazing intensities.
Material and Methods
A rangeland adjacent to Khabr National Park in Kerman province was selected as the study area. The study area is shrub- dominated species Artemisia aucheri Boiss. Three sites with different grazing intensities (for example, exclosure, high grazing and moderate grazing) were sampled. At
each site, three 100m transects with 50m intervals were set up. Ten quadrats were randomly assigned to each transect. For each quadrat, the species met were recorded and their number of individuals and the amount of forage produced were measured. The annual forage production (forage quantity) was measured using the clip and weigh method. To determine forage quality, crude protein, acid detergent fibre (ADF), dry matter digestion and metabolizable energy were estimated for each species. Additionally, a soil sample was taken from each of the quadrats. The samples were air-dried and sieved with a 2 mm sieve. The organic carbon of the soil samples was determined through wet oxidation with Walkley-Black chromic acid. Then, the species importance index (IVI) was estimated using relative frequency (Fr), relative density (Dr) and relative dominance (Dor). One-way ANOVA and LSD were used to compare different grazing intensities in terms of soil carbon, annual production, crude protein, ADF and metabolizable energy. Pearson's correlation was used to examine the relationship between soil carbon and annual production with the qualitative attributes of production, ie. The primary component analysis (PCA) was used to identify the most important species in terms of production at the three sites with different grazing intensities (exclosure, high grazing and moderate grazing). Principal Component Analysis (PCA) was used to identify the most important species in terms of production at the three sites with differing grazing intensities (exclosure, high grazing and moderate grazing).
Results and Discussion
The quantity and quality of forage has been reduced in the livestock grazing sites. The study area has a long history of cattle grazing, which has significantly altered the composition of the vegetation. About 26% of the exclosure site species had been removed from the plant composition of medium pasture sites, most of which are appetizing species. Although the amount of organic carbon in the soil increased at the exclosure site, it was not significantly different from grazing sites. Therefore, despite the improvement in forage quality and quantity, soil organic carbon had shown a lower reaction to the exclosure. Due to the presence of acceptable species, there was a positive relationship between forage quantity and quality at the exclosure site. Although A. aucheri was still dominant shrub species in the site with medium grazing intensity, there was no significant relationship between forage quantity and quality due to the decrease of palatable species. With the increase in the number of non-platable species in the high grazing site, there was a significant negative relationship between forage quantity and quality. There was a positive and meaningful relationship between soil carbon and the amount and quality of forage at the exclos site. The relationship between soil carbon and forage quantity and quality was not significant on grazing sites because of a change in plant composition. In the sites under grazing, palatable forbs such as Tragopogon jesdianus Boiss. and Lathyrus annuus L. were not observed and perennial grasses were significantly reduced. It should be noted that forage production of forbs has not changed much on the site with average grazing compared to the exclosure site. Perennials, especially woody plants, were severely reduced at the site with high grazing intensity. There were no bushes observed at that location. Annual grasses had increased in the site with heavy browsing. As perennials decrease, space and resources become available for the invasion of annual plants, especially annual grasses. Therefore, Bromus tectorum L. had the highest forage production in the high grazing area. In terms of crude protein, the high grazing area had low quality forage. Since livestock grazing and subsequent changes in plant composition do not greatly impact soil carbon, livestock management can contribute to the improvement of plant composition and forage production at this site. Taking into account the impact of grassland management on other ecosystem functions, it is suggested to explore the relationship between the amount of production and other functions of quality rangeland ecosystems in order to sustainably manage rangeland ecosystems.
Rangeland provides numerous ecosystem goods and services. Most rangeland management decisions focus on forage production, and this can lead to the loss of other rangeland ecosystem services. One of those services is carbon sequestration, the removal of carbon dioxide from the Earth's atmosphere and its storage in the ground. Rangeland, which covers approximately half of terrestrial ecosystems, is one of the most important sinks for atmospheric carbon dioxide. Photosynthesis, respiration and decomposition are the main processes in the ecosystem that determine how carbon is stored in the soil. Anthropogenic activities like livestock grazing can significantly alter soil carbon storage. Unfortunately, human activities have resulted in lower soil carbon and increased global climate change. Livestock grazing is one of the most significant factors affecting the structure and functioning of ecosystems. Grazing livestock can affect the amount of carbon in the soil through reduced vegetation cover, altered species composition, soil degradation, urination and defecation. On the other hand, changes in the quantity and quality of forage production by livestock grazing have a strong effect on the welfare of the beneficiaries. Consequently, knowledge of the relationship between forage production and other ecosystem goods and services such as soil carbon is essential to the sustainability of ecosystems. It is important to study the quantity and quality changes in rangeland production in relation to different livestock grazing intensities on soil carbon. However, this information can assist range managers in providing techniques to promote soil carbon storage. The purpose of the study is 1) to determine annual forage production in rangelands at different grazing intensities, 2) to study the quality of rangeland forages produced, 3) to assess soil carbon content at different grazing intensities, and 4) to assess the relationship between rangeland production and soil carbon content at different grazing intensities.
Material and Methods
A rangeland adjacent to Khabr National Park in Kerman province was selected as the study area. The study area is shrub- dominated species Artemisia aucheri Boiss. Three sites with different grazing intensities (for example, exclosure, high grazing and moderate grazing) were sampled. At
each site, three 100m transects with 50m intervals were set up. Ten quadrats were randomly assigned to each transect. For each quadrat, the species met were recorded and their number of individuals and the amount of forage produced were measured. The annual forage production (forage quantity) was measured using the clip and weigh method. To determine forage quality, crude protein, acid detergent fibre (ADF), dry matter digestion and metabolizable energy were estimated for each species. Additionally, a soil sample was taken from each of the quadrats. The samples were air-dried and sieved with a 2 mm sieve. The organic carbon of the soil samples was determined through wet oxidation with Walkley-Black chromic acid. Then, the species importance index (IVI) was estimated using relative frequency (Fr), relative density (Dr) and relative dominance (Dor). One-way ANOVA and LSD were used to compare different grazing intensities in terms of soil carbon, annual production, crude protein, ADF and metabolizable energy. Pearson's correlation was used to examine the relationship between soil carbon and annual production with the qualitative attributes of production, ie. The primary component analysis (PCA) was used to identify the most important species in terms of production at the three sites with different grazing intensities (exclosure, high grazing and moderate grazing). Principal Component Analysis (PCA) was used to identify the most important species in terms of production at the three sites with differing grazing intensities (exclosure, high grazing and moderate grazing).
Results and Discussion
The quantity and quality of forage has been reduced in the livestock grazing sites. The study area has a long history of cattle grazing, which has significantly altered the composition of the vegetation. About 26% of the exclosure site species had been removed from the plant composition of medium pasture sites, most of which are appetizing species. Although the amount of organic carbon in the soil increased at the exclosure site, it was not significantly different from grazing sites. Therefore, despite the improvement in forage quality and quantity, soil organic carbon had shown a lower reaction to the exclosure. Due to the presence of acceptable species, there was a positive relationship between forage quantity and quality at the exclosure site. Although A. aucheri was still dominant shrub species in the site with medium grazing intensity, there was no significant relationship between forage quantity and quality due to the decrease of palatable species. With the increase in the number of non-platable species in the high grazing site, there was a significant negative relationship between forage quantity and quality. There was a positive and meaningful relationship between soil carbon and the amount and quality of forage at the exclos site. The relationship between soil carbon and forage quantity and quality was not significant on grazing sites because of a change in plant composition. In the sites under grazing, palatable forbs such as Tragopogon jesdianus Boiss. and Lathyrus annuus L. were not observed and perennial grasses were significantly reduced. It should be noted that forage production of forbs has not changed much on the site with average grazing compared to the exclosure site. Perennials, especially woody plants, were severely reduced at the site with high grazing intensity. There were no bushes observed at that location. Annual grasses had increased in the site with heavy browsing. As perennials decrease, space and resources become available for the invasion of annual plants, especially annual grasses. Therefore, Bromus tectorum L. had the highest forage production in the high grazing area. In terms of crude protein, the high grazing area had low quality forage. Since livestock grazing and subsequent changes in plant composition do not greatly impact soil carbon, livestock management can contribute to the improvement of plant composition and forage production at this site. Taking into account the impact of grassland management on other ecosystem functions, it is suggested to explore the relationship between the amount of production and other functions of quality rangeland ecosystems in order to sustainably manage rangeland ecosystems.
Introduction Groundwater is among the most precious natural resources for human health, economic development and environmental diversity. Since the measurement of groundwater parameters and water quality is difficult, costly and far from... more
Introduction
Groundwater is among the most precious natural resources for human health, economic development and environmental diversity. Since the measurement of groundwater parameters and water quality is difficult, costly and far from being available, interpolation techniques are an easy solution. At the same time, there is a strong correlation between groundwater quality and land use in areas with sensitive aquifers. Changes in land use caused by factors such as rapid growth and expansion of urban centers, rapid population growth, and the lack of land, the need for increased production and the evolution of technologies are important concerns. The literature review shows that the quantitative and qualitative decline in groundwater is a global crisis. As a result, the factors affecting the quantitative and qualitative decline in groundwater range from climate factors to socio-economic factors.In the current research, find an answer to the poor condition of the Isin Plain aquifer by looking at the relationship between some hydrological factors and changes in cultivation pattern of the region is the main goal. For this purpose, the water table and EC of groundwater were interpolated using geostatistical methods. Using satellite imagery, the trend of culture pattern changes over time was obtained. Finally, the relation between the factors on the Isin plain was established.
Material and Methods
For this purpose, the quantity and quality of groundwater in eastern and western Isin plains were interpolated using the Kriging and IDW methods, during the four statistical years of 2004, 2011, 2018, and 2021 and the time series of 2004-2021. The RMSE statistic was used to evaluate the performance of the methods.Then, satellite images and ground truth data was used for land use change classes to investigate the land use changes during the cropping season, along with the determination of changes in the quantity and quality of groundwater in the eastern and western Isin plains for the mentioned years. Satellite data including Landsat 5 multi-temporal satellite images in 2004, 2011, and 2018 and Landsat 8 and Sentinel 2 images for February 2021 were obtained from the USGS.Following preparation of the related images using the flash module,
atmospheric and radiometric corrections were performed. Then, the corrections information was extracted into the text file appended to each image. With field survey, the coordinates of the representative pixels were determined and seven land use classes of gardens, vegetables, bare lands, residential and industrial areas, saline lands, and Prosopis Cineraria and Juliflora species were determined. The maximum likelihood classification method was used to separate seven main land use classes based on 127 training samples. For the purpose of assessing accuracy, an error matrix was created for the producer's accuracy, the user's accuracy, the overall accuracy, and the kappa coefficient calculation. Finally, to examine the relationship, the land use map and the groundwater and EC interpolation maps were overlapped into the Arc Map software environment.
Results and Discussion
By comparing the interpolation methods of IDW and Kriging with the RMSE validation technique, it was found that the best interpolation method for estimating water table and EC is Kriging, followed by the IDW method. A review of the land use maps of the Eastern and Western Plains of Isin showed the increase and decrease of different land use categories over the years under study. The overall accuracy and Kappa coefficient were over 82% and 0.79, indicating the acceptable accuracy of the classification and maps obtained. The results of overlapping land use maps and spatial changes in ground water indicate that the location of agricultural land, especially gardens in the eastern Isin plain and vegetables in the western Isin plain, is compatible with the areas of having low water table. The results of overlapping the land use map obtained from Landsat 8 data and EC spatial changes showed the highest amount of EC in can be observed in Prosopis Cineraria and Juliflora species and residential and industrial uses in eastern and western Isin plain. The results obtained from Sentinel2 indicate that the value of EC was significant in the bare lands of eastern Isin and in the saline lands of western Isin. However, the increase in agricultural use, especially for gardens and vegetables, and the pairing with areas with the lowest water table indicates an over-extraction of groundwater for agricultural purposes. On the other hand, the significant extent of bare lands and the upward trend of saline lands, residential and industrial areas, and matching with areas with high EC and the adaptation of maximum EC with Prosopis Cineraria and C. juliflora species uses may be a warning for poor condition of the Isin plain aquifer.
Groundwater is among the most precious natural resources for human health, economic development and environmental diversity. Since the measurement of groundwater parameters and water quality is difficult, costly and far from being available, interpolation techniques are an easy solution. At the same time, there is a strong correlation between groundwater quality and land use in areas with sensitive aquifers. Changes in land use caused by factors such as rapid growth and expansion of urban centers, rapid population growth, and the lack of land, the need for increased production and the evolution of technologies are important concerns. The literature review shows that the quantitative and qualitative decline in groundwater is a global crisis. As a result, the factors affecting the quantitative and qualitative decline in groundwater range from climate factors to socio-economic factors.In the current research, find an answer to the poor condition of the Isin Plain aquifer by looking at the relationship between some hydrological factors and changes in cultivation pattern of the region is the main goal. For this purpose, the water table and EC of groundwater were interpolated using geostatistical methods. Using satellite imagery, the trend of culture pattern changes over time was obtained. Finally, the relation between the factors on the Isin plain was established.
Material and Methods
For this purpose, the quantity and quality of groundwater in eastern and western Isin plains were interpolated using the Kriging and IDW methods, during the four statistical years of 2004, 2011, 2018, and 2021 and the time series of 2004-2021. The RMSE statistic was used to evaluate the performance of the methods.Then, satellite images and ground truth data was used for land use change classes to investigate the land use changes during the cropping season, along with the determination of changes in the quantity and quality of groundwater in the eastern and western Isin plains for the mentioned years. Satellite data including Landsat 5 multi-temporal satellite images in 2004, 2011, and 2018 and Landsat 8 and Sentinel 2 images for February 2021 were obtained from the USGS.Following preparation of the related images using the flash module,
atmospheric and radiometric corrections were performed. Then, the corrections information was extracted into the text file appended to each image. With field survey, the coordinates of the representative pixels were determined and seven land use classes of gardens, vegetables, bare lands, residential and industrial areas, saline lands, and Prosopis Cineraria and Juliflora species were determined. The maximum likelihood classification method was used to separate seven main land use classes based on 127 training samples. For the purpose of assessing accuracy, an error matrix was created for the producer's accuracy, the user's accuracy, the overall accuracy, and the kappa coefficient calculation. Finally, to examine the relationship, the land use map and the groundwater and EC interpolation maps were overlapped into the Arc Map software environment.
Results and Discussion
By comparing the interpolation methods of IDW and Kriging with the RMSE validation technique, it was found that the best interpolation method for estimating water table and EC is Kriging, followed by the IDW method. A review of the land use maps of the Eastern and Western Plains of Isin showed the increase and decrease of different land use categories over the years under study. The overall accuracy and Kappa coefficient were over 82% and 0.79, indicating the acceptable accuracy of the classification and maps obtained. The results of overlapping land use maps and spatial changes in ground water indicate that the location of agricultural land, especially gardens in the eastern Isin plain and vegetables in the western Isin plain, is compatible with the areas of having low water table. The results of overlapping the land use map obtained from Landsat 8 data and EC spatial changes showed the highest amount of EC in can be observed in Prosopis Cineraria and Juliflora species and residential and industrial uses in eastern and western Isin plain. The results obtained from Sentinel2 indicate that the value of EC was significant in the bare lands of eastern Isin and in the saline lands of western Isin. However, the increase in agricultural use, especially for gardens and vegetables, and the pairing with areas with the lowest water table indicates an over-extraction of groundwater for agricultural purposes. On the other hand, the significant extent of bare lands and the upward trend of saline lands, residential and industrial areas, and matching with areas with high EC and the adaptation of maximum EC with Prosopis Cineraria and C. juliflora species uses may be a warning for poor condition of the Isin plain aquifer.
Land degradation is manifested by a significant decrease in the biological productivity of the land, following natural events or inappropriate human activities. The consequences of these processes are threats to food security, economic... more
Land degradation is manifested by a significant decrease in the biological productivity of the land, following natural events or inappropriate human activities. The consequences of these processes are threats to food security, economic well-being and environmental issues caused by the reduce use of water, soil and plant resources. The aim of the present research is to compare and measure the state of land degradation based on the Global Assessment of Soil Degradation (GLASOD) model and the Iranian Model of Desertification Potential Assessment (IMDPA). For this purpose, the Yazd-Ardakan plain, located in Central Iran, was selected as the study area. The land unit map of the area was prepared. The severity of land degradation was then investigated using the GLASOD and IMDPA models in each of the land units. The assessment of the accuracy and performance of the two models was carried out by calculating the overall accuracy and kappa coefficient of the production maps, as well as the nonparametric tests of Spearman and Mann-Kendall. The results of the accuracy evaluation showed that the IMDPA production map corresponded to the actual field data of 82%, whereas this correspondence for the GLASOD model was 69%. According to the IMDPA and GLASOD models, desertification is increasing significantly in 33% and 12% of the region, respectively. The intensity of desertification in the moderate class is closing to the severe class. With no strategies for reducing or controlling desertification in the region, the area of land where desertification is severe will increase in the near future. In general, the lack of plant cover is the main factor contributing to increasing the intensity of desertification in the Yazd-Ardakan plain. This problem is the result of the combination of natural factors and destructive human factors in the region, which has significant effects on increasing the process of desertification and soil degradation in this plain.
The dust storm is recognized as a global problem which has a large-scale negative impact on the world. Dust strong winds transport them long distances. The dust storm caused a lot of damage to the economy, health and the environment.... more
The dust storm is recognized as a global problem which has a large-scale negative impact on the world. Dust strong winds transport them long distances. The dust storm caused a lot of damage to the economy, health and the environment. Therefore, an adequate understanding of the origin and time of dust storms can be effective in reducing dust damage. The purpose of the ongoing research is to identify the source of the dust storm events. For this purpose, the dust events in a period of 11 years were analyzed using the synoptic meteorological data of Kermanshah. The number of 646 dust storms were identified, and their detection operations and identifying of the areas affected by dust storm and areas of origin were performed using MODIS and Deep Blue. The HYSPLIT was used to route the dust storm and the entry routes of dust storm into the Kermanshah city. Based on the dust codes, the highest number of dust storms per year was registered in 2008 and 2009, respectively. Most dust storms were observed in summer and during May, June and January. The results of DRS, HYSPLIT have shown that the western directions have the largest amount of dust input in Kermanshah, and the MODIS and Deep Blue images also confirm this fact. Overall, the findings showed that most of the routes come from the north and centre of Iraq and the Syrian Desert. Dust storms originate at the border and arid lands of northern and central Iraq and Syria.
Net primary production is a sensitive index to changes in climatic factors and human activities. The present study was conducted with the aim of quantitatively evaluating the relative role of climate change and human activities on the... more
Net primary production is a sensitive index to changes in climatic factors and human activities. The present study was conducted with the aim of quantitatively evaluating the relative role of climate change and human activities on the development of desertification in Torbat Heydarieh and Bojnoord based on the spatio-temporal variations of net primary production. First, primary net production was estimated by ground measurement. Subsequently, it was simulated using the CASA model in statistical period between 1986 and 2017. Six scenarios were designed to determine the relative role of climate change and human activities in the expansion or inversion of desertification. The results of the research showed that net primary production has declined over the 31-year period and that the trend in its changes is negative. An examination of different desertification scenarios showed that the city of Bojnord is under the scenario of expansion of desertification due to climate change, and Torbet Heydarieh city is under the scenario of desertification expansion due to the interaction between climate change and human activities. Based on this, the trend of changes in actual and potential primary net production in Bojnord and Torbat Heydarieh cities was negative and its intensity was classified in the low to medium decline category. Also, the slope trend of changes in primary net production caused by human activities in Torbat Heydarieh city was positive and in the low to medium increase class, and in Bojnord city, it was negative and in the low decrease class.The study of the development or return of desertification scenarios showed that 61.23% of the total area of the study area was affected by the expansion and development of desertification due to the impacts of climatic factors, and 38.77% of those affected by the interaction of climatic factors and human activities in expansion of desertification.
Soil contamination by heavy metals is a significant environmental problem worldwide. Human activities, including mining, are a source of pollution to natural resources. In this study, the phytoremediation potential of rangeland species... more
Soil contamination by heavy metals is a significant environmental problem worldwide. Human activities, including mining, are a source of pollution to natural resources. In this study, the phytoremediation potential of rangeland species including, Artemisia sieberi Besser, Zygophyllum atriplicoides Fisch. and C.A. Mey for the absorption of heavy metals of Ni, Co, As, Cr and V was investigated around the bauxite crusher of the Jajarm alumina mine in the direction of the prevailing wind. Soil sampling was performed at the distances of 450-700, 800-1200, 1400-2000 and 2500-5000 meters from the center of the bauxite crusher, and the control site. For this purpose, the seeds were planted in pots with a 3:1:1 ratio of sand, fertilizer and soil. Two-months later, they were transferred to pots with soils sampled from target distances. After completing of a vegetative period, the phytoremediation potential of the species was performed a factorial experiment in a completely randomized block design with three replications in greenhouse conditions. Results indicated that As, Ni, Cr, and Co absorption in above/underground of A. sieberi tissues were higher than Z. atriplicoides. But V absorption in above/underground of Z. atriplicoides tissues were higher than that for A. sieberi and between the vanadium accumulation in the aerial and underground organs of the target species and distances a significant difference was observed at the level of 1%. The amount of heavy metals transfer factor for A. sieberi and Z. atriplicoides was more and less than one in turn. Therefore, in terms of the transfer factor, A. sieberi has a potential for phyto-extraction and Z. atriplicoides has a potential for phyto-stabilization. The results also showed that A. sieberi and Z. atriplicoides were recognized as hyper-accumulating of nickel and cobalt metals. These species can therefore be recommended for the ecological restoration of soils polluted by heavy metals, especially nickel and cobalt in similar regions.
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The abundance of agricultural waste and fishing is one of the environmental issues in various regions. Converting these wastes to biochar and using them in the soil is a way to enhance diverse ecosystems and plays a vital role in... more
The abundance of agricultural waste and fishing is one of the environmental issues in various regions. Converting these wastes to biochar and using them in the soil is a way to enhance diverse ecosystems and plays a vital role in environmental sustainability. In the present study, the effect of shrimp (Fenneropenaeus merguiensis) and eggplant (Solanum melongena) biochar suspension on certain chemical characteristics of sandy soil was investigated. For this purpose, samples of sandy soil from the agricultural lands around Bandar Abbas were collected intact in PVC columns with a height of 25, and diameter of 20 cm. Then the prepared suspension of shrimp and eggplant biochar was added to the soil in a completely random design in three concentrations of 0, 4, and 8 g/l in three replications. After adding the different soil treatments into columns, they were incubated for 100 days at a humidity range of field capacity and 50% of it was kept in nursery condition. Next, some soil chemical properties including of pH, EC, N, K, Ca, Mg, and Na were measured. Statistical analysis and comparison of means at P<0.05 between various treatments were performed using a one-way analysis of variance and the Duncan’s test in SPSS16. The results of ANOVA showed that the application of both types of biochar had a significant effect on the chemical properties of sandy soil, so that the application of shrimp and eggplant waste biochar caused a significant increase in the amount of K, N, and pH, and a decrease in EC, Na, and Ca compared to the control treatment. The maximum value of K was related to the concentration of 8 g/l of shrimp and eggplant biochar and the maximum value of N was obtained by applying 8 g/l of shrimp biochar. In addition, the increase in the concentration of the two types of biochar indicates an increase in K and N values. The lowest CE value was obtained by applying 8 g/l of eggplant biochar. Based on the results obtained, shrimp and eggplant biochar waste are suggested in the sand soil amendment.
Dust is one of the most important atmospheric phenomena, which has attracted the attention of many scientists as an emergent phenomenon. Current research has studied trend of the number of dust days and its relation to climatic parameters... more
Dust is one of the most important atmospheric phenomena, which has attracted the attention of many scientists as an emergent phenomenon. Current research has studied trend of the number of dust days and its relation to climatic parameters and vegetation index from 2005 to 2017 in the Yazd-Ardakan plain. The DSI was computed for the two meteorological stations at Yazd and Meybod. By classifying the two Landsat 7 and 8 satellite images, the land form/cover maps, including agricultural lands, urban, mantled pediments, covered pediment and erg have been prepared. The NDVI layer was then computed in two classes for the Landsat 7 and 8 satellites. The class area was calculated for all levels of the region and also within two buffers of 10 and 20 km at the center of stations Yazd and Meybod. The relationship between the climatic parameters, including annual average temperature, annual average precipitation and annual average relative humidity, was then calculated. Finally, the relationship between dust index and land form types, NDVI layer and climatic parameters has been investigated. The results showed that the relationship between the DSI and the erg type is direct, but there is an inverse relation with the mantled pediments, covered pediment and agricultural land. Based on the results obtained, urban lands have little effect on the dust storm index. By comparing the DSI with the NDVI, with the increase in the region's dust storm index, the NDVI values for all levels decreased. By comparing the DSI with the climatic parameters, with the decrease in annual average precipitation and relative humidity and the increase in annual average temperature, the dust Storm index increased.
Long-term drought prediction is of considerable importance in water resources management. Time series models are appropriate tools to predict climatic events. In this study, the Reconnaissance Drought Index (RDI), which is based on... more
Long-term drought prediction is of considerable importance in water resources management. Time series models are appropriate tools to predict climatic events. In this study, the Reconnaissance Drought Index (RDI), which is based on precipitation and potential evapotranspiration, was applied to calculate droughts of Yazd synoptic station at time scales of one, three, and six months from 1961 to 2018. The period 2006-2018 was selected as the forecast period. Drought data of the forecast period were not considered to the applied models. Results showed that the pattern of drought data at 1, 3 and 6-month time scales in the Yazd synoptic station is seasonal. The SARIMA is a univariate time series model created by adding a seasonal component to the ARIMA model. The SARIMAX multivariate model is created by adding parameter covariate variable (exogenous variable) to SARIMA. In the present study, the efficiency of the seasonal univariate model (SARIMA) and seasonal multivariate model (SARIMAX) in predicting drought in arid regions were compared. To implement the SARIMAX model to predict droughts, precipitation and potential evapotranspiration were provided to the model as covariates, separately. The results of the coefficient of determination (R2) between observed RDI and predicted RDI values by SARIMA showed that the model offers higher performance on 3 and 6-month time scales with 0.66 and 0.71, respectively. The results of the SARIMAX model showed that in one-month time scale, the SARIMAX model based on potential evapotranspiration with 0.60, and for 3-month time scale, the SARIMAX model based on precipitation with 0.79 performed better. In 6-month time scale, the performance of the model for the both covariates were almost the same with the coefficient of determination of 0.79. Comparison of the results of the two models showed that the performance of the SARIMAX model is higher than the SARIMA model for drought predicting in arid regions.
The preparation of geological maps based on field data and the application of aerial photographs have always been an error because of the structural diversity of the earth and the difficulty of accessing certain regions. But in recent... more
The preparation of geological maps based on field data and the application of aerial photographs have always been an error because of the structural diversity of the earth and the difficulty of accessing certain regions. But in recent decades, the use of satellite imagery has but in recent decades, the use of satellite imagery has gone a long way to increasing the accuracy and timeliness of geological mapping. The purpose of the current study is to investigate the applicability of Landsat 8 satellite images and object-oriented pixel classification methods in mapping the geological formations of some part of the Shirkuh Mountain range in Yazd province. This area is part of the scattered mountain range of Central Iran with a dry climate and minimal vegetation. Initially, enhanced operations were performed to identify geological information’s using MNF, PCA and FCC processing. Then, the images were classified using object-oriented algorithms (BAYES, SVM, KNN, Decision Tree and Random Forest), neural network (ARTMAP, RBF, MLP and SOM), and base pixels (Maximum Likelihood, Minimum Distance, Mahalanobis and SAM). Next, the error rate of each method was calculated using Boolean logic and kappa coefficient. The results showed that the maximum probability classification with kappa coefficient of 75% in the base pixel category, Fuzzy ARTMAP classification in neural network method with kappa coefficient of 72% and Bayesian classification in object-oriented method with kappa coefficient of 82% have the best results among other methods. These results show that the methods mentioned in the identification and separation of geological formations are effective. The SAM of pixel-based methods, SOM of neural network methods and RF of object-oriented methods with 49, 64 and 61%, respectively, showed the lowest accuracy in each category.
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Lack of rainfall and its high temporal and spatial variation are the main problems of vegetation restoration in Iran. Rainfall harvesting methods can play an effective role in improving soil moisture. Rainfall harvesting operations have... more
Lack of rainfall and its high temporal and spatial variation are the main problems of vegetation restoration in Iran. Rainfall harvesting methods can play an effective role in improving soil moisture. Rainfall harvesting operations have a great impact on the structure and function of ecosystems. Therefore, the present study investigates the changes of soil properties as a result of implementing two rainfall harvesting methods (water spreading system and micro-catchment) in arid rangelands of Hormozgan province. First, 45 soil samples were taken from control, micro-catchment and water spreading system sites and their physical and chemical properties were measured in the soil laboratory. One-way analysis of variance was used to compare the different sites in terms of soil properties. The rate of change index was used in order to assess the performance of soil properties and the overall performance of each of the rainfall harvesting methods compared to the control. Synergy and trade-off relations between soil properties were investigated using Pearson correlation coefficient. The results showed that except EC, pH, TNV, water spreading system had a significant effect on soil properties. EC, pH, TNV, calcium, magnesium, nitrogen and sand had negative performance in the water spreading system, and the rest of the soil properties had positive performance. The overall performance of soil properties was 31 and 11% in the micro-catchment, and 52 and 25% in the water spreading system. Sand had a significant trade-off relationship with most soil chemical properties. The highest trade-off was observed between sand and silt (p <0.01, R2 = -0.99). The highest synergy was observed between silt and phosphorus (p <0.01, R2 + 0.87), and next phosphorus and OC (p <0.01, R2 + 0.72). In general, the positive impact of water spreading system on the soil properties of arid rangelands was greater than the micro-catchment in this region.
Data on the different types of crops and cultivated areas were extracted from 11 cities of South Khorasan province in the growing season of 2019-2020 to evaluate the biodiversity of agricultural crops in this province. Subsequently, this... more
Data on the different types of crops and cultivated areas were extracted from 11 cities of South Khorasan province in the growing season of 2019-2020 to evaluate the biodiversity of agricultural crops in this province. Subsequently, this information was divided into various groups to calculate biodiversity indices. Crop categorization was based on the consumption type (cereals, beans, industrial crops, vegetables, grapevine, forage crops, and medicinal plants) and plant family. The finding indicate that 35 crop species are grown in this province. The largest area cultivated is cereals at 65.01%, the second for forage crops at 11.1%, and the third of medicinal plants at 10.8%. According to the results, the production systems of the agricultural ecosystems of South Khorasan do not show a rich diversity. The diversity index was very low among all agricultural groups and plant families. Of the groups studied, cereals, medicinal plants and fodder crops were more diversified than others. The groups of plants with the greatest variety were Poaceae and Iridaceae. Qaen and Boshruyeh cities had a more desirable diversity than the other cities resulting in the richness of the species and a higher homogeneity and Shannon index. However, the diversity indices were low in cities of Ferdows, Sarbisheh, Darmian, and Khoosf. Since the preservation and development of biodiversity is one of the key components to achieve stability in agriculture, attention to the biodiversity of agricultural crops seems to be crucial in South Khorasan province, especially in low-diversity cities.
Due to the water shotages in arid and semi-arid climates, rainfed agriculture faces severe challenges. It is therefore essential to carry out specific studies on the efficiency factors of rain-fed crop growth. The purpose of this study... more
Due to the water shotages in arid and semi-arid climates, rainfed agriculture faces severe challenges. It is therefore essential to carry out specific studies on the efficiency factors of rain-fed crop growth. The purpose of this study was to assess the factors affecting the duration of the different phenological stages of rain-fed barley in a semi-arid region. For this purpose, duration of phenological stages for five different growth periods of rain-fed barley including sowing-emerge, emerge-tillering, tillering-stem, stem-flowering, and flowering-maturity were extracted at the Sararoud station, Kermanshah, during the period of 2000-2015. By calculating 12 variables for these periods, the variables with significant impacts were detected for each of them and Principal Component Analysis (PCA) technique was used to assess the impact of these variables on different phenological stages duration. The results showed that between different selected variables, the degree-days-based variables (GDD and PTU) and absorb radiation-based (net radiation and daily mean soil surface temperature) showed the highest impact on all of the phenological stages duration. Each of the evapotranspiration-based variables, soil moisture supply variables and complementary variables influenced duration of two growth stages. The highest variability of the different growth periods which explained by the selected variables in the current research using principal component analysis was obtained for sowing-emerge stage. The overall results showed that the principal component analysis not only has a high capability to detecting effective factors on the different phenological stages duration, but also is a powerful tool to regulate the interrelate impacts between variables.
The loss of water from reservoirs in the country, especially in the central and southeast regions, due to the dry climate and high temperatures are significant, causing stress on water resources. There is a need to reduce the amount of... more
The loss of water from reservoirs in the country, especially in the central and southeast regions, due to the dry climate and high temperatures are significant, causing stress on water resources. There is a need to reduce the amount of evaporation from the surface of the reservoirs in order to conserve the country's usable water resources of the. In the present study, the effectiveness of Palma dactylifera L. mats with two coverage levels of 50 and 100% as evaporation reducion coatings- has been studied. To examine the performance of the mentioned methods on reducing water losses, Colorado evaporation pans were used at the Semnan University. The effectiveness of the mentioned coatings was studied with three replicates and in comparison, with the control for 30 days in different seasons of 2018, using the comparison means method. Based on the results of average comparison test using Duncan's method, the 50% and 100% coatings showed a significant 1% difference with the control in terms of evaporation and water temperature. Results indicate in spring, pans covered with 50% and 100% mats reduced evaporation by 9% and 70%, respectively, and by 0 and 72%. in summer. In autumn, it showed a decrease in evaporation of 39% and 72%, and in winter, and a decrease in evaporation of 38% and 78% compared to the control. In general, palm mat Palma dactylifera L. with 100% coverage has shown the best performance on the surfaces of Colorado evaporation pans. Results show that in arid lands and desert regions, palm mat covering are expected to reduce evaporation from water reservoirs and basins.
Desertification, as a complex process, is a serious threat to the environment in many parts of the world, especially in arid regions. With accurate knowledge of the factors influencing the spread of desertification and appropriate... more
Desertification, as a complex process, is a serious threat to the environment in many parts of the world, especially in arid regions. With accurate knowledge of the factors influencing the spread of desertification and appropriate management strategies, the impacts of this process can be controlled or reduced. The aim of the current study was to identify and assess indicators and indices of desertification for the assessment and mapping of sensitive areas of the Kavir-e-Namak basin in Khorasan Razavi province, to desertification. In this study, an assessment model of sensitive areas to desertification (ESAs or MEDALUS), available data based on field studies in 2021, was used. At first, five criteria including soil, climate, vegetation, erosion and human activities were identified as the main criteria for desertification. Then, on the basis of the opinions of over 40 natural resource experts, the indices of each criterion were classified, weighted and assessed. The quality of each criterion was determined by the calculation of the geometric average of the indices. Finally, the map of areas sensitive to desertification in the study area was produced using GIS. The identification of management strategies was conducted using the Delphi approach and distributing a two-cycle questionnaire based on scenario planning and future studies. The results showed that among the criteria for desertification in the study area, climatic criteria, human activities, soil and erosion with values of 1.54, 1.53, 1.51 and 1.50, respectively, are the most important criteria followed by the vegetation criterion with a value of 1.45 as a next effective criterion of desertification. Results indicate that 12% of the study area are in the fragile class, and approximately 88% in the moderate to severe critical class. Based on scenario planning and method of futures studies, the best and worst scenarios in four different categories including adaptive management and organizational cohesion, economic and social empowerment of local communities, educational development, culture and advertising, and participatory implementation of natural resource projects as comprehensive management strategies were developed.
Although land degradation is a worldwide challenge and a destructive phenomenon, little studies have been done on the application of new numerical methods (data mining and statistically), for spatial simulation of this phenomenon and... more
Although land degradation is a worldwide challenge and a destructive phenomenon, little studies have been done on the application of new numerical methods (data mining and statistically), for spatial simulation of this phenomenon and identification of areas sensitive to land degradation. The aim of this study is to spatially simulate land degradation in the Qazvin plain using the frequency ratio model to identify areas prone to land degradation. For this purpose, using the trend of changes in net primary production during the years 2001 to 2020, the points of occurrence of land degradation in the Qazvin plain were determined. Approximately 70% and 30% of the points were used to prepare the land degradation vulnerability map and validate the model's efficiency, respectively. For this research, 15 parameters affecting land degradation (directly and indirectly) including temperature, rainfall, slope, aspect, elevation, EC and SAR of ground water, ground water level, annual ground water decline, land use, normalized difference vegetation index, normalize difference salinity index, vegetation soil salinity index, normalized difference moisture index, and visible and shortwave infrared drought index, were introduced into the model as predictors factors or independent parameters. Finally, using the area under the ROC curve, the effectiveness of the frequency ratio model for spatial simulation of land degradation was assessed. The map of land degradation susceptibility shows that the areas prone to degradation are located in the northeast, north, northwest, west, southwest, and south of the Qazvin plain, which mainly includes good, moderate and poor rangelands. For the land use parameter, the highest frequency ratio was associated with the sum of good, moderate, and poor rangeland (5.66). The value of AUC = 0.7 indicates the good performance of the frequency ratio model in spatial simulation of land degradation.
Wind erosion and dust storms are among the most important natural hazards and have negative impacts on environment and people. The Hamoun international wetland- located in the southeast of Iran and southwest of Afghanistan, at the estuary... more
Wind erosion and dust storms are among the most important natural hazards and have negative impacts on environment and people. The Hamoun international wetland- located in the southeast of Iran and southwest of Afghanistan, at the estuary of the Helmand River – due to the severe droughts during the last three decades has become the main source of soil erosion. The purpose of this study is to investigate the sensitivity of wind erosion in the Iranian section of the Hamoun wetland as the Hamoun wildlife refuge. Byliterature reviewing and using experts’ knowledge, 15 effective criteria in the phenomenon of wind erosion were determined and weighted by using AHP method. The weights analysis showed that among the criteria, vegetation cover with 0.13 had the highest weight. Using satellite images related to November 2021, the SAVI vegetation index was prepared as an index of the amount of vegetation cover. To prepare the soil criteria maps, 135 pints of surface soil were taken and transferred to the lab. After determining the criteria value in each sample, the map of each criterion was prepared using the IDW method. The criteria were standardized using the FUZZY method, and then combined by applying the calculated weights and using the weighted linear combination method to prepare the wind erodibility model. The prepared model was classified into five erodibility classes. To assess model accuracy, the wind erosion threshold speed was calculated by installing a portable wind tunnel device at 40 sites. The resulting figures were classified into five levels according to the erodibility classes, and compared with the corresponding erosion class of the wind tunnel sites. An overall accuracy of 81% for the prepared model shows capability of this model to prepare an accurate wind erosion model.
Iran's location in the drylands belt has increased the frequency of dust storms in western parts of Iran, particularly the city of Kermanshah and negative environmental impacts. Arid lands, as one of the main sources of suspended dust in... more
Iran's location in the drylands belt has increased the frequency of dust storms in western parts of Iran, particularly the city of Kermanshah and negative environmental impacts. Arid lands, as one of the main sources of suspended dust in the atmosphere, face problems such as sandstorms, high levels of dust particles and reduced visibility, which are major climate problems in the country, especially in the border provinces. The purpose of the present study is to investigate the performance of a numerical model between the meteorological-chemical atmosphere scale called WRF-Chem model in the simulation of the concentration of suspended particles in Kermanshah region. By comparing the spatial distribution and concentration of suspended particles, meteorological parameters simulated by the model, and the available observational values for PM10 particles in Kermanshah, the efficiency of the WRF-Chem model was evaluated. The results of the simulation of PM10 particles for the studied days showed that the central and western deserts of Iraq, Syrian desert, Kuwait and northern Saudi Arabia are the main source of dust storm. Due to the logical correlation between dust particle emissions and temperature and relative humidity parameters, accurate estimation of these parameters is very effective in PM10 particle simulation accuracy. Based on the analysis of the PM10 variables, temperature and relative humidity and the plotted graphs and their comparisons, a favorable agreement was achieved between the simulated and measured values for PM10, temperature and relative humidity.
In addition to the increase in prone areas to wind erosion processes in western Azarbaijan province due to the drying of Lake Urmia, there is a growing concern regarding the intensification of dust storms. Considering the impacts of this... more
In addition to the increase in prone areas to wind erosion processes in western Azarbaijan province due to the drying of Lake Urmia, there is a growing concern regarding the intensification of dust storms. Considering the impacts of this phenomenon on the environment, public health, agriculture, and transportation sections, more detailed studies on its source, severity, and frequency is necessary. Therefore, this study was designed to assess the temporal and spatial changes of dust storm events using satellite data, to detect the dust source, and to analyze the factors affecting the occurrence of dust storms in western Azarbaijan province. Analysis of the number of dusty days using the MODIS-AOD product indicated that the years 2003, and 2008 to 2012 were the dust storm peaks during the period 2000-2020 at western Azarbaijan province. Most dust storm events have occurred in summer and spring seasons, and monthly changes indicate the maximum dust storm between March and October. Trend analysis indicated that there was no significant trend in AOD and dust storm events. Among vegetation and climate variables, there is a significant relationship between AOD and wind speed (i.e., the correlation is about 64%). Spatially, dust storms occur more frequently along the shores of Urmia Lake (mostly in the east and south and slightly in the west). Southern areas of the province reported a higher frequency of dust event than the central and northern parts of the province. Due to the direction of the prevailing wind, it seems to be most affected by dust storms coming from the neighboring country of Iraq, however, the areas around the Lake Urmia are the inner source of dust storms.
The aim of the present study is to investigation the effect of different land uses (forest, rangeland, cane brake and bare land) on carbon sequestration and soil erosion in Jazink region located in Zahak city, Sistan and Baluchestan... more
The aim of the present study is to investigation the effect of different land uses (forest, rangeland, cane brake and bare land) on carbon sequestration and soil erosion in Jazink region located in Zahak city, Sistan and Baluchestan province. For this purpose, following the field evaluation of various land uses, soil samples were taken from at depths of 0-30 cm and 30-60 cm for each land use. Some soil properties including organic carbon, texture, bulk density, sequestered carbon and soil stability index (MWD) were measured according to standard methods. Data analysis was performed using one-way ANOVA analysis in a completely randomized block design, and the averages were compared by Tukey test at 95% confidence level using SPSS software. The results showed that the amount of bulk density at various soil depths in cane brake land use had the lowest of 0.992 and 0.956 gr/cm3, respectively, and in the bare land had the highest value about 1.59 and 1.61 gr/ cm3, respectively. Carbon sequestration in land use by cane brake was 3234.02 and 2455.32 kg/ha, respectively, and in bare land, it was the lowest around 1967.37 and 987.65 kg/ha. Soil stability in the bare land was the lowest at 0.342 mm and the highest in the canebrake land use at 1.67 mm. Higher amount of carbon and organic matter in the soil and the lower bulk density indicates that the soil is more stable and resistant to erosion. In this region, cane brake and forest land uses have the highest degree of stability and carbon sequestration among land uses. These results can be very useful for decision-making and for choosing suitable management practices and desertification programs in arid areas such as this region.
Vegetation is one of the most important key components in arid regions for reducing of the effects of erosion and determining the severity of desertification. Decrease in vegetation leads to increase in surface albedo. Accessing and... more
Vegetation is one of the most important key components in arid regions for reducing of the effects of erosion and determining the severity of desertification. Decrease in vegetation leads to increase in surface albedo. Accessing and preparing desertification intensity map at the fastest possible time and at the lowest cost is one of the concerns of governments. In the present study, in order to identify the best vegetation index for preparing the desertification intensity map, MSIL-1C data of Sentinel 2 satellite in the arid region of Sistan has been used. For this purpose, the relationship between surface albedo and each of the different vegetation indices of the NDVI, RVI, DVI, PVI, SAVI and TSAVI were conducted. After determining the linear regression equation between the albedo and each of the mentioned indices, the relevant desertification intensity equation was calculated and the desertification intensity map of the studied area at 5 classes was prepared based on albedo and each of the mentioned indices. The results showed the strongest relationship in the study area was between albedo and NDVI, with a correlation coefficient of 0.63, and the lowest correlation of 0.37 was between the albedo and PVI indices. Based on the present study among the indices studied, the NDVI is the best for the preparation of maps of desertification intensity in the arid region of Sistan. Based on this index, 20.3% of the region was classified as severe and 32.9% of the region grouped into the moderate desertification class.
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Meteorological drought is a complex natural disaster that occurs everywhere in the world. Predicting the occurrence and severity of drought can be effective in managing water crises and their impacts. The purpose of the current study is... more
Meteorological drought is a complex natural disaster that occurs everywhere in the world. Predicting the occurrence and severity of drought can be effective in managing water crises and their impacts. The purpose of the current study is to select the most appropriate model from statistical models and artificial intelligence (artificial neural networks) to predict drought in Isfahan synoptic station during the span period of 1990-1920 using the Z-Score index (ZSI). In this study, the capability and efficiency of the SARIMA stochastic linear model and three advanced learning machine models of the Feedforward Neural Networks (FNNs), Multi-layer Perceptron (MLP), and Extreme Learning Machines (ELM) were evaluated based on Root Mean Squared Error (RMSE), Mean Absolute Square Error (MASE) and Mean Absolute Error (MAE). The results showed that among the many models made, the Feedforward Neural Networks (FNNs) model with RMSE of 0.33, MASE of 0.02, and MAE of 0.22 were selected as the best model. Using the superior model, precipitation for the period of 2025-2021 of Isfahan synoptic station was predicted, then based on the ZSI drought index, drought intensity of forecast precipitation data in 3, 6, 9, 12-month time scales, 18, and 24 months was calculated. The results of drought severity predicting showed that severe drought in 3 and 6 month time scales in 2021 and 2023 and in 9 and 18 month time scales in 2024, moderate drought in all time scales in 2024, and weak droughts occurred at the 3, 6, and 24-month time scales in 2024 and 2025, respectively. Overall, the results showed that the use of feed neural network model was more efficient. Since predicting drought at all time scales can reveals drought more accurately, this predicting in turn to facilitate the development of water resources management strategies for management of drought is effective.
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TWater deficit is considered as one of the limited factors in agriculture in the arid and desert regions of the country. The cultivation of drought tolerant plants such as safflower (Carthamus tinctorius L.) and using methanol to increase... more
TWater deficit is considered as one of the limited factors in agriculture in the arid and desert regions of the country. The cultivation of drought tolerant plants such as safflower (Carthamus tinctorius L.) and using methanol to increase the drought resistance of these plants is an appropriate solution for agricultural development in these regions. For this purpose, an experiment was carried out in the design of split plots in a randomized complete block with three replications in the growing season of 2019-2020 in Iranshahr. Experimental treatments were consisted of three drought stress levels including no stress, moderate stress and severe stress, as the main plots, and the four methanol levels including no use, using 10, 20 and 30% volume of methanol as sub plots. The results showed that the highest values of the studied traits were obtained from no stress treatment and foliar application of 30% volume of methanol. However, for the 1000 grain weight, grain and oil yield, there were no statistically significant differences between 30 and 20% by volume of methanol. For all the studied traits, there was no statistically significant difference between the absence of stress treatment and the absence of methanol use, with moderate stress treatment and foliar application of 30% methanol volume. The lowest values of the traits studied were achieved by severe stress treatment without foliar application.
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The present study aimed at preparing the potential distribution map and identifiying the environmental requirement of Prosopis farcta L. using tree-based and regression methods in the marginal rangeland of Niatak river in Sistan region.... more
The present study aimed at preparing the potential distribution map and identifiying the environmental requirement of Prosopis farcta L. using tree-based and regression methods in the marginal rangeland of Niatak river in Sistan region. For this purpose, species presence data was recorded randomly. Environmental variables were prepared using field sampling and digital elevation model. In order to achieve the pseudo-absence points, first habitat modeling was performed using the domain model, then pseudo-absence points were prepared using the prediction map obtained from this method. Species distribution modelling was conducted using random forest (RF), classification and regression trees (CART) and generalized additive model (GAM). The accuracy of the models used was evaluated using the area under curve criterion. Result showed that the RF with area under curve 0.98 has the highest accuracy. Generalized additive models and classification and regression trees were ranked after RF. The highest and lowest values of kappa index were assigned to the RF with 0.75, and GAM with 0.43 Kappa value. Accordingly, the RF model is the most accurate model in predicting the potential habitat distribution. Analysis of the variable’s importance showed that in the studied scale, edafic factors and distance from the river have greater effect on species distribution than other factors. So that, in all models used, acidity and electrical conductivity were identified as the most important variables. In general, it is suggested that habitat development plans for Prosopis farcta should be planned in the central and marginal parts of the Niatek river due to better suitability of these regions for species distribution.
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The present study was aimed at studying the physiological and phonological characteristics of Salivia eremophila Boiss. as a native and medicinal species in three rangeland sites in Yazd province, Iran. For this perpose three areas... more
The present study was aimed at studying the physiological and phonological characteristics of Salivia eremophila Boiss. as a native and medicinal species in three rangeland sites in Yazd province, Iran. For this perpose three areas (Damaghan, Tange-Chenar and Ghavam abad) and three sites in each area, were investigated in terms of soulobe carbohydrates, proline, chlorophyll and carotenoids in aerial parts of Salivia eremophila in two phonological stages of flowering and seeding. Plant sampling was done based on randomized-systematic method in 1m2 plots, along with 50 m2 transects. Phenolocical diagram of Salivia eremophila was drived based on consecutive field investigations. The results showed that there are significant differences in the interaction effects between phonological stage, site and area. Site #1 of Tange-Chenar had significant difference in Chlorophyll (a and b) with the other sites (p<0.05). For carotenoids, there was a significant difference between sites and areas where Damgahan Site #3 at the seeding stage and Tange-Chenar Site #1 had the highest rates. Proline levels at Damgahan Site #1 (at the flowering stage) were higher than at other sites and areas, and showed a significant difference. The amount of soulobe carbohydrates showed a significant difference in sites and phonological stages in general (except the flowering stage). In overall, the climate conditions of the studied sites are nearly similar in terms of annual rainfall, as well as rangelans type and altitude, and this can affect the occurrence of low changes in plant nutrients.
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Dust, the main pillar of air pollution, has always been an important subject of study on several levels. Over the last few years, it has become increasingly concentrated in various regions. The present study, which uses Google Earth... more
Dust, the main pillar of air pollution, has always been an important subject of study on several levels. Over the last few years, it has become increasingly concentrated in various regions. The present study, which uses Google Earth engine system and MODIS satellite data with 8-day temporal resolution and spatial resolution of 1km and 250m, as well as statistical methods such as correlation and averaging of Triple Exponential Smoothing (TES), to monitor and predict spatial and temporal changes of airborne dust in Qazvin province. For this purpose, using Aerosol Optical Depth Index (AOD) images, Optimal Vegetation Index (EVI) and Modis Heat Island (HI) change index, and preparing their temporal and spatial monitoring maps during the statistical period 2015-2020 and predict to 2030, the relationship between these factors was examined. The results of the present study showed an increase in the quantity of airborne dust in Qazvin province from 0.461 in 2015 to 0.603 in 2017. his rate was then reduced by 0.493 in 2018 and by 0.575 in 2019. The quantity of airborne dust, then fell slightly to 0.5366 in 2020. The results showed a negative relationship between precipitation, relative humidity and vegetation, and a positive relationship between wind speed, freezing days, temperature, variations in temperature islands and hours of sunshine with AOD. The present study also examined changes in airborne dust concentrations in two high- and low-risk classes, and predicted a high-risk class for 2030. This finding is helping policymakers and planners reduce dust pollution in cities through vegetation management and reduce the heat islands, as well as implement climate programs to manage precipitation and moisture in cities.
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In recent years, droughts, frequent storms, industrial and mining activities have caused a rise in dust in suburbs Tehran, and developing west of the province of Teheran. The Mallard County is located in the west of the province of... more
In recent years, droughts, frequent storms, industrial and mining activities have caused a rise in dust in suburbs Tehran, and developing west of the province of Teheran. The Mallard County is located in the west of the province of Tehran with arid and desert climate and has been selected as the study area. This study aims to determine the soluble metals, minerals and morphology of the original sediments and particulates in Mallard County and to determine the origin of the dust. Dust sediment was collected seasonally at 30 stations using dust collector. Soil and surface sediment sampling were conducted systematically and randomly on 14 pediment and playa facies and a total of 83 samples were taken from the work units. Scanning electron microscope (SEM) was used to determine the shape and size of dust particles, and X-ray diffraction (XRD) identified the minerals found in dust particles. The results showed that most of the chemical compounds in the dust particles consist of magnesium, phosphorus, potassium, iron, chromium, vanadium, nickel, lithium, molybdenum, caesium, scandium, zirconium and titanium. These elements are in the form of quartz, calcite and gypsum clay minerals with a coating of dolomite, hematite and muscovite minerals, with an internal origin that have been transported into the region from close distances or through wind flow. According to the results of the SEM analysis, the particle morphology is angular and semi-circular. Most dust particles can be evidence of the existence of a local and human source and are transported closely.
Mapping of wetlands using remote sensing has faced challenges due to different land cover classes and similar reflectance across land cover classes. Synthetic aperture radar (SAR) data have a special ability to detect phenomena because of... more
Mapping of wetlands using remote sensing has faced challenges due to different land cover classes and similar reflectance across land cover classes. Synthetic aperture radar (SAR) data have a special ability to detect phenomena because of their penetration capacity, as well as their independence from time and weather conditionsIn this study, radar data were used to map the land cover of Hamoun wetlands in both wet and dry conditions. For this purpose, L-band capacity has been used to investigate land cover classes. Statistical indicators were used for assessing the separation between land cover classesThe images were classified using the method of the support vector machine. The results of the present study show the capacity of the L-band to separate different land cover classes. The results of the accuracy assessment show an overall accuracy of over 80% in preparing the land cover map of the region. Furthermore, because of the penetration of the L-band, it is possible to detect water in the underlying layer of plants. The results of this study showed that the difference between the reflectance of vegetation that their smaller portion is below the water, and vegetation, most of which is above the water is detectable by the L-band. The difference between their backscatter is 6 dB in the HV and about 2 dB in the HH polarization, which indicates the capaity of the HV polarization to separate these two classes.
One of the ecological crises is the degradation of Nebka's ecosystems that threatens environmental stability and causes many regional and trans-regional impacts, such as increasing the risk of wind erosion. The aim of this study was to... more
One of the ecological crises is the degradation of Nebka's ecosystems that threatens environmental stability and causes many regional and trans-regional impacts, such as increasing the risk of wind erosion. The aim of this study was to investigate the trend of spatial and temporal changes in future land cover with Nebka and accumulated erosive sediments around the phanerophyte species Salvadora persica L. and Alhaji camelorum L. in the Persian Gulf and Oman sea. Thus, Markov chain and satellite images were used to simulate the existing land uses, and trend of temporal and spatial changes. Land cover maps were prepared for the years 2001, 2011, and 2021, using Landsat satellite data and applying maximum likelihood supervised classification method. After model evaluation procedures, the land cover maps for 2030 and 2040 were predicted using both Markov chain and automatic cell model. Results of land cover changes in 2001, 2011 and 2021 showed that the areas of Nebka have decreased by 1047.9 ha. Predictive maps for 2031 and 2041 with an overall accuracy of 91.4% and kappa coefficient of 0.88%, have high accuracy. The sediment levels of nebka will decrease from 8.67% in 2021 to 4.26% in 2031 and 2.09% in 2041, respectively. The decrease in the area of nebka in the past and predicting the downward trend of changes in nebka land in the future showed that the natural barriers to the movement of suspended sediment were destroyed and reduced.
Due to the importance of halophyte species in the reclamation of saline lands, the present study was conducted to investigating the effects of different levels of salinity on growth traits and enzymatic of Salsola imbricata in a... more
Due to the importance of halophyte species in the reclamation of saline lands, the present study was conducted to investigating the effects of different levels of salinity on growth traits and enzymatic of Salsola imbricata in a completely randomized design (CRD) with three replications and seven levels of salinity including 3, 10, 20, 30, 40, 50, and 60 dS m-1 at research greenhouse of National Salinity Research Center. Traits of stem length, root length, root-shoot length ratio, collar diameter, number of branches, protein content, catalase, peroxidase, and proline were measured. Results showed that different levels of salinity were significant for all studied traits except peroxidase. Increasing salinity levels from 3 dS m-1 to 60 dS m-1 , significantly reduced shoot length at the rate of 20%, root length 30%, root-shoot length ratio 11%, collar diameter 38%, and the number of branches per plant 29%. Increasing salinity from 3 dS m-1 to 40 dS m-1 decreased protein content by 30%, but the protein content increased by 26.7% by increasing salinity up to 50 and 60 dS m 1. Results of enzymatic activities showed that increasing salinity significantly increased the amount of catalase, peroxidase, and proline, so the highest of these compounds was observed at 60 dS m 1 .
Land subsidence is a vertical movement downwards of the Earth's surface. It is difficult to identify or measure because of rapidly depleting ground water. This hazard, as a hydrogeomorphology phenomenon, is revealed in many areas of the... more
Land subsidence is a vertical movement downwards of the Earth's surface. It is difficult to identify or measure because of rapidly depleting ground water. This hazard, as a hydrogeomorphology phenomenon, is revealed in many areas of the country because of the uncontrolled depletion of the groundwater. There are a number of methods for identifying and determining the rate and range of subsidence. Radar interferometry (D-INSAR) technique is known as a robust technique for land subsidence measurement. This method has superior features in terms of cost, accuracy, scale of the study area and time, in comparison with other detection methods, and can provide a precise estimation of the phenomenon. In this study, the Abarkouh plain was studied from January 2016 until February 2018. Sentinel 1 sensor images using radar interferometry technique were used to estimate subsidence. To identify the impact of groundwater extraction in land subsidence, groundwater fluctuations data from 44 piezometric wells, and also land subsidence data were analyzed using regression models. Results showed that the highest rate of groundwater depletion occurred in the town of Mehrdasht and around the agricultural fields, which led to the maximum rate of subsidence up to 12 cm/year. Ccorrelations coefficient between aquifer fluctuations and land subsidence rate is 0.79 that indicated significant relation between these parameters.
It is possible to maintain a stable balance and restore desert ecosystems by growing salinity-tolerant species. In this study, Plantebac moisture absorption plates in establishment and growth Haloxilon ammodendron (C.A. Mey.) Bunge ex... more
It is possible to maintain a stable balance and restore desert ecosystems by growing salinity-tolerant species. In this study, Plantebac moisture absorption plates in establishment and growth Haloxilon ammodendron (C.A. Mey.) Bunge ex Fenzl were used in the Segzi Salt Plain, in Isfahan province from 2018 to 2021. Soil analysis was also conducted before and after the use of plantbac plates. The desired treatments were the irrigation cycle treatment which was considered at two levels of two and four weeks, plant-bac and control treatment. Results showed that the Haloxilon ammodendron seedlings gradually decreased in height, canopy cover and viability. This decline in growth, size and number of seedlings over the past year compared to the previous years was significant at the level of 1% probability for height and canopy level, and 5% for survival. This is due to unfavourable soil and water conditions in the area in terms of texture and salinity. The Plantbac plates block the transport of these soil salts to the surface, while irrigation causes the accumulation of salts into the environment around the roots, and thus reduces the growth of Haloxilon ammodendron. The presence of plant-like plates in the soil under the seedlings stopped the capillary flow and as a result, the accumulation of soluble salts in the root zone of the plant, which leads to moisture stress in the plant.
Wind erosion is one of the problems in arid and semi-arid regions that is associated with the process of detachment and transportation of soil particles by wind. The Wind Erosion Risk Index is a framework for modelling wind erosion that... more
Wind erosion is one of the problems in arid and semi-arid regions that is associated with the process of detachment and transportation of soil particles by wind. The Wind Erosion Risk Index is a framework for modelling wind erosion that examines the sensitivity of land to wind erosion based on a set of surface and climate thresholds. The purpose of the study is to assess the risk of wind erosion in various geobiofaces at Abarkouh plain, Yazd province, using the WEHI model from 2003 to 2017. Three factors including frequency of erosive winds, percentage of bare land and soil surface moisture were used to run the model. Wind erosion risk map was produced under three categories: low, moderate and severe. To evaluate the effectiveness of the model, aerosol optical depth (AOD) data were used that confirmed the accuracy and significance of the model (α=0.01). The results showed that 107,369 ha of lands in the severe wind erosion category was increased. Wind erosion is widespread in the study area, particularly in the geobiofaces of the salt-lake and saline lands. The risk of wind erosion is reduced only on near-dense farmlands. This may expose the land upstream of the study area to the hazards of salt storms given biological, economic and social threats.
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Selenium (Se) and silicon (Si) are identified to affect plant physiological attributes and yield parameters. Se and Si’s effective roles in reducing various environmental stresses in plant of Origanum vulgare L. are unknown and need to be... more
Selenium (Se) and silicon (Si) are identified to affect plant physiological attributes and yield parameters. Se and Si’s effective roles in reducing various environmental stresses in plant of Origanum vulgare L. are unknown and need to be investigated. This study aimed to examine the role of Si and Se application on O. vulgare under drought stress and the effect of these two elements on physiological traits and yield parameters of O. vulgare. The impact of the foliar spraying of Se and Si under drought stress conditions was studied through a split factorial experiment with three replications in greenhouse conditions at the Yazd University. Drought, as the first factor in three stress levels of 30, 70 and 100% of field capacity, and nutrient factors including Se in three levels of control, 15 and 30 mg/l, and Si in three levels of control, 150 and 300 mg/l were sprayed. Foliar spraying of Se 30 mg/l had a significant effect on the increase in proline, soluble sugar, chlorophyll, carotenoids, phenolics compounds, and fresh and dry shoot weights. The foliar spraying of Si 150 mg/l had a significant effect on the increase in proline compared to the control traits. The change in foliar spray quantity of Si has no significant impact on changes in yield parameters. The combined foliar spraying of Se and Si to reduce the effects of drought stress has been more effective than applying just one of these elements in improving the physiological attributes of O. vulgare. The solution of 30 mg/l Se and 15 mg/l Si has a higher yield under drought stress conditions of 70% of the field capacity.
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Nowadays, desertification and land degradation are among the most important environmental chalenges caused by various factors, including climate variation and human activities, especially in arid and semi-arid regions. Therefore,... more
Nowadays, desertification and land degradation are among the most important environmental chalenges caused by various factors, including climate variation and human activities, especially in arid and semi-arid regions. Therefore, understanding of the desertification status is essential for future management and planning. In this regard, using remote sensing indicators to prepare basic desertification maps and its monitoring can be efficient. In this study, Topsoil grain size and albedo indices were used as indicators to identify desertification in the center of Khuzestan province. After constructing the above-mentioned indices using Landsat ETM+ sensor image, the values of 411 randomly selected samples on the images were used to construct the Albedo-TGSI feature space model. The correlation between the variables was 0.83. The DDI desertification degree equation is then obtained based on the slope of the fitted line. In the next step, by applying natural break classification on the DDI index, different levels of desertification and the break values were obtained for random samples. These break values are then applied to the whole study area, and finally, the 2018 desertification status map was obtained. Results indicated that about 70% of the study area fell under the severe and high desertification intensities, whereas 18.3%, 8.3% and 4.1% fell under the medium, low and none desertification grades respectively. The accuracy of the produced map with a kappa of 92.1% and an overall accuracy of 94.3% showed that the feature space model is a useful and robust tool for extracting desertification degrees in barren lands or areas with extremely low vegetation coverage.
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This study aimed at predicting the effect of climate change on the geographic distribution of Thymus kotschyanus Boiss and Hohen in Mazandaran province. Species presence data were recorded via the Global Positioning System (GPS). The... more
This study aimed at predicting the effect of climate change on the geographic distribution of Thymus kotschyanus Boiss and Hohen in Mazandaran province. Species presence data were recorded via the Global Positioning System (GPS). The distribution of T. kotschyanus Boiss and Hohen under current and future climatic conditions 2050 and 2070 (1428- 1448 Solar) applying two scenarios of RCP 4.5 and RCP 8.5 climate change by using the GCM data series of general circulation models BCC-CSM1-1، CCSM4 and MRI-CGCM3 and the five species distribution models such as Generalized Linear Model, Generalized Additive Model, Classification Tree Analyses, Generalized Boosting Model and Random Forest methods was investigated. For this purpose, layers of environmental factors, including six bioclimatic and two physiographic variables, were used as inputs to species distribution models. Among the environmental variables, precipitation seasonality, precipitation in the coldest quarter, and isotherm had the greatest impact on habitat suitability. The assessment of the modelling indicated that the Generalized Additive Model and Generalized Boosting Model had better predictions of climate habitat than the other models. The results also indicate that climate change will change the range size of the T. kotschyanus Boiss and Hohen, and will move toward higher elevations in the future. The results of the present study may be used to plan habitat protection for the medicinal species of T. kotschyanus Boiss and Hohen, as well as its restoration and rehabilitation in the vast regions of the country.
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Community participation in desertification projects lowers costs and makes projects more effective. Through strategic policies for the restoration, conservation and sustainability of natural resources, the government is implementing... more
Community participation in desertification projects lowers costs and makes projects more effective. Through strategic policies for the restoration, conservation and sustainability of natural resources, the government is implementing programs, and individual, cultural, social and economic factors play an effective role in increasing the participation of villagers in desertification projects. The objective of this study was to study and prioritise factors affecting the participation of villagers in Mohammad Shahkaram area of Zahak city, where desertification projects have been implemented in its northern zone. Data collection tool is a questionnaire. According to Cochran's formula, the number of samples required was 358 questionnaires and for questionnaire reliability, 30 questionnaires for the sample were tested in advance. The analysis of the data was based on descriptive statistics and inferential analysis. Results of the AHP method and multivariate regression analysis showed that the independent entered variables can predict 57% of the variables related to the village participation rs in desertification projects. Among the variables studied, age and work experience of individual factors with a Pearson coefficient of 0.216 and local responsibility from social factors have the highest correlation with participation rate. Maintaining desertification projects in the region puts in the first rank, and sociocultural index factors have a higher priority than variables dependent on participation in desertification projects than economic index and planning.
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In many areas of Iran wher water is scarce, including the western Khorasan, people have understood the importance of water and soil resources. They have made great efforts to protect them, and they also gained valuable experiences. The... more
In many areas of Iran wher water is scarce, including the western Khorasan, people have understood the importance of water and soil resources. They have made great efforts to protect them, and they also gained valuable experiences. The use of these experiences in the construction of the Bandsars allowed optimizing the water and soil resources and the localization of watershed management operations which will improve the effectiveness of those operations. The bandsars cause the sedimentation of suspended particles by controlling the flow rate, and consequency, in addition to the increase in soil fertility, improve the recharge of groundwater, vegetation cover and desertification control. This research studies the effect of the use of flood in bandsars, located in the south of the city of Sabzevar on soil fertility using both field and laboratory methods. To achieve this, 5 Bandsars sites were selected in the study area, and in each site 3 soil profiles inside the bandsars and also 3 profiles outside the Bandsars with 60 cm depth were digged. The soil samples were collected from three depths of 0-20, 20-40 and 40-60 cm. Soil samples were transported to the laboratory and the amount of organic mater, N, P and K were measured. Results were analysed using t as well as Dankan tests. Results showed that the values of the fertilizing elements such as organic mater, N, P are different between inside and outside the bandsars, and are higher inside the bandsars comparing to the related outside areas. Although this difference is not statistically significant in some cases, it can be concluded that Bandsars improved soil fertility.
Sand dunes are one of the most dynamic geomorphic features of the earth's surface. Accordingly, identifying the factors affecting the mobility of sands and predicting their future status is essential to control dust. The study area was... more
Sand dunes are one of the most dynamic geomorphic features of the earth's surface. Accordingly, identifying the factors affecting the mobility of sands and predicting their future status is essential to control dust. The study area was selected due to the location of Sabzevar city in the busiest railway line of the country, and the condition of sand dunes around this city. For this purpose, after calculating the percentage of erosive winds and drought index, the Lancaster index based on the average annual rainfall ratio and annual potential evapotranspiration for the period of 1990-2016 was calculated for analysis of sand dunes' mobility status. To predict the effect of climate change on the mobility of sand dunes, a sensitivity analysis test was carried out. The results show that the values of the Lancaster index in this station did not show the inactive status in this span time period. The results of the analysis of the relationship between drought index and mobility of sand dunes show a significant effect of drought on the mobility and activity of sand dunes. Finally, the results of sensitivity analysis showed that if the frequency of erosive winds and evapotranspiration potential increases by 30%, the activity of sand dunes in the Sabzevar station will increase by 38%. Also, due to the potential of solid particles in creating dust, the location of sand dunes, and the study of local dust at Sabzevar station, the priority is to stabilize the hills located in the east of the study area.
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The purpose of this study is to investigate the effect of floodwater spreading on the vegetation of Abdalan plain after 24 years since the implementation of the project. For this purpose, the changes in vegetation density and diversity... more
The purpose of this study is to investigate the effect of floodwater spreading on the vegetation of Abdalan plain after 24 years since the implementation of the project. For this purpose, the changes in vegetation density and diversity and soil characteristics of the floodwater spreading were considered as the basis for the effectiveness of various floods. To determine the characteristics of density and percentage of vegetation, percentage of rocks, gravels, litter, and bare soil as well as Physico-chemical characteristics of soil in each area of floodwater spreading and control, 3 transects with a length of 100 meters were deployed. Measuring and sampling were performed on one square meter plots. The results of field studies led to the identification of 36 plant species and 33 genera belonging to 14 plant families. The most important plant families in the region are Asteraceae, Poaceae, and Fabaceae. The results showed that there are 34 plant species in the floodwater spreading area and 25 plant species in the control area. Of these, 12 plant species were observed only in the floodwater spreading area and 2 plant species were observed only in the control area, and 23 plant species were common in both areas. According to the results, the percentage of cover and density of plants in the floodwater spreading area has increased compared to the control area by 32.8% and 4.4%, respectively. The percentage of clay, silt, and sand has increased compared to the control in the field of floodwater spreading. Sufficient moisture and suitable fine-grained sediments to maintain the required moisture for a longer time as well as the seeds in the sediments have caused the growth and increase of density and canopy cover of plants in the field of floodwater spreading. These operations on the Abdalan plain have caused the revitalization of the region by changing the physical characteristics of the surface soil and improving vegetation conditions.
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In recent decades, the increase in temperature has caused widespread climate change all over the world, especially in arid and semi-arid regions of Iran and Yazd province. The purpose of this study is to project climate change in Yazd... more
In recent decades, the increase in temperature has caused widespread climate change all over the world, especially in arid and semi-arid regions of Iran and Yazd province. The purpose of this study is to project climate change in Yazd province using the CanESM2 model and new emission scenarios (RCP) during 2021-2050 (near future) and 2051-2080 (distant future) and to study the trend of changes in the baseline period using the Mann-Kendall test. The statistical indices of R2, RMSE, and NSE were used to evaluate the performance of the CanESM2 model. According to the results, the model had an appropriate performance for projecting precipitation and temperature in the future period and was classified into good and very good classes in terms of capability. Investigating the trend of the annual change of temperature and precipitation in the baseline period showed that the temperature had an increasing trend under most scenarios and stations, while the trend of the change of precipitation was no significant. The results of temperature changes in Yazd province indicated an increase of 2.2, 1.2, and 2.5 °C during 2021-2050 and 2.28, 3.19, and 4.77°C during 2051-2080 under RCP2, RCP4.5, and RCP8.5 scenarios, respectively. Changes in precipitation in Yazad province during the winter season showed a decrease in precipitation by 32, 26, and 34% during 2021-2050 and by 32, 32, and 5% during 2051-2080 under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively.
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This study aimed to identify the epicenter and co-occurrence factors of dust storm waves in Kermanshah from 16 to 18 June 2016. To investigate the synoptic conditions of the causes of this phenomenon, data set with a resolution of 0.125º... more
This study aimed to identify the epicenter and co-occurrence factors of dust storm waves in Kermanshah from 16 to 18 June 2016. To investigate the synoptic conditions of the causes of this phenomenon, data set with a resolution of 0.125º arcs from the European Center for Medium-Term Atmospheric Prediction (ESMWF), including geopotential height at 500 hPa, omega at 700 hPa, sea level pressure, orbital components and meridian at 300 hPa level, specific moisture at 700 hPa level, soil moisture up to 10 cm depth and dust optical depth were used. To route, the origin of dust particles, the Lagrangian method of the HYSPLIT model was used 48 hours before the occurrence of dust phenomenon in Kermanshah at three altitude levels of 200, 1000, and 1500 m. The dust storm was also simulated using WRF-chem numerical weather forecasting model. Finally, through the processing of MODIS satellite images, its scope was determined. Examination of HYSPLIT tracking maps showed that the central and western deserts of Iraq and the Syrian are the main sources of dust for the study area. In synoptic conditions, simultaneously with the occurrence of rising dust, cyclonic systems play a significant role in the transmission of this phenomenon. Significant strengthening of the Iraqi low-pressure system along with the formation of traffic in the Zagros mountains has caused the creation and transfer of dust in the warm period of the year to the study area. The spatial distribution of the dust interpreted by the MODIS images is consistent with the spatial distribution of the dust concentration simulated by the WRF-chem model.
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The occurrence of droughts and wet periods can affect the quantity and quality of surface and groundwater. In the present study, the 3-year drought and wet periods were determined using 23year rainfall data of four meteorological stations... more
The occurrence of droughts and wet periods can affect the quantity and quality of surface and groundwater. In the present study, the 3-year drought and wet periods were determined using 23year rainfall data of four meteorological stations and the SIAP index. To investigate the physicochemical properties of groundwater, after considering the data of observation wells in the Eastern part of Gorgan plain, 14 deep and semi-deep wells were selected. Then, three criteria of EC, SAR, and Na were used to assess the water in the agricultural sector and the Schoeller diagram was used to assess the water in the drinking sector. To estimate the significant differences between the physicochemical properties of groundwater in the three periods of the wet period, drought, and long-term, an F-test at the probability level of 0.05 was used. The results revealed that the water quality of semi-deep wells is better than for deep wells in agriculture and drinking water sections. Based on the Piper diagram, the chemical facies of semi-deep wells are less diverse than deep wells. The results of both deep and semi-deep wells showed that chemical facies in the dry season show a greater tendency to achieve seawater composition. The results of the F test showed that there is a significant difference with 95% probability between groundwater quality parameters in semi-deep aquifers in wet and dry periods. In contrast, the occurrence of wet and dry periods in the study area had little effect on the physicochemical properties of deep aquifers.
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Land use and land cover (LULC) is one of the most important factors that affect the desertification risk in this study, the desertification sensitivity of the Mokhtaran basin in South Khorasan province was estimated by integrating LU/LC... more
Land use and land cover (LULC) is one of the most important factors that affect the desertification risk in this study, the desertification sensitivity of the Mokhtaran basin in South Khorasan province was estimated by integrating LU/LC scenarios with the MEDALUS environmentally sensitive areas (ESAs) model to predict the desertification risk. The four main MEDALUS criteria including soil, climate, vegetation, and management were examined to assess the sensitive areas to the desertification. Land use maps were categorized using the Landsat satellite imageries of TM, ETM+, and OLI sensors for 1987, 1998, 2003 as a past scenario, and 2015 as a current scenario. Land use maps for 2025 and 2035 were produced as the future scenario based on the simulation of CA-Markov models. The validation results confirmed the model accuracy by calculating the kappa coefficient of 0.95. The land use map was predicted for the years 2025 and 2035 based on the transition rules and a transition area matrix. The results showed that the rainfed area was reduced by 68.29 km2 and the agricultural land was increased by 25.35 km2 during theperiod. In the protection area of playa-bare lands, the changes showed this area was increased by 26.86 km2. The rangeland has also experienced positive changes with an increase of 18.83 km2. Compared to the current scenario, the desertification trend in the future scenario was positively predicted by increasing the area of critical areas from 30.9% to 48.7% over 20 years. The most susceptible lands to desertification were known as playa-bare lands.
Drought forecasting is of particular importance in water resources management. Drought forecasting allows planners to schedule for reducing the negative impacts of drought as well as to adapt to it. Drought prediction is more important in... more
Drought forecasting is of particular importance in water resources management. Drought forecasting allows planners to schedule for reducing the negative impacts of drought as well as to adapt to it. Drought prediction is more important in arid regions. Because these areas are inherently water scares and the consequences of drought in these areas are more severe. Due to the high variabilities of the temporal and spatial distribution of precipitation in these areas, the frequency of drought is higher and results in more difficulty to model and predict drought. In this study, since drought time series is nonlinear and cyclic, nonlinear autoregressive neural networks (NARs) were used to predict short-term and long-term drought in Yazd synoptic station from 2006 to 2018. Reconnaissance Drought Index (RDI) which in addition to precipitation, considers potential evapotranspiration to monitor droughts, for one, three, and six months timescales was calculated. Potential evapotranspiration was calculated using the FAO-Penman-Monteith method. The results of short-term (one month) drought prediction presented that the model provides high performance in predicting three and six months RDI values. The results of long-term (13-years) drought forecasting (without access to real drought data from 2006 to 2018) indicated that RDI values in dry months show best fit to real values in three months' timescale. To improve the efficiency of the model in the long-term drought forecasting, long-term precipitation and potential evapotranspiration (without model access to real data from 2006 to 2018) were predicted. RDI values were then calculated based on the predicted precipitation and potential evapotranspiration data. The results showed that the prediction accuracy increased in one and three months scales. Also, on six months' timescale, RDI data were more accurately predicted in dry months.
Wind erosion and its control has always been one of the important topics in arid regions. Therefore, this study aimed to assess the potential of remote sensing data in mapping this phenomenon based on the wind erosion indicators of IRIFR... more
Wind erosion and its control has always been one of the important topics in arid regions. Therefore, this study aimed to assess the potential of remote sensing data in mapping this phenomenon based on the wind erosion indicators of IRIFR model in Isfahan province. For this purpose, different parameters including land topography, wind speed, desert pavement, vegetation cover, soil moisture, aeolian sediments, land use and land management were extracted from MODIS, Landsat and SRTM space shuttle, and combined using fuzzy logic. Then, the accuracy of produced map was assessed with 200 random points and error matrix against field-based wind erosion map which was obtained from IRIFR model. Results showed that wind erosion is more dominant in Naein, Aran and Bidgol, Ardestan and Isfahan counties. According to the produced wind erosion map, 26.3% of the study area was classified as low, 56.9% as moderate, 11.8% as high and 5% as very high. The overall accuracy of more than 73% between produced and field-based maps indicated the high performance of remote sensing data in mapping of wind erosion. Therefore, due to many advantages of these data, the presented method can be used to map and report wind erosion condition at different spatial and temporal scales.
Temperature is one of the most important physical parameters that control the transfer and exchange of energy between different layers of the earth and the atmosphere. LST estimation methods based on satellite images require surface and... more
Temperature is one of the most important physical parameters that control the transfer and exchange of energy between different layers of the earth and the atmosphere. LST estimation methods based on satellite images require surface and atmospheric parameters such as surface emissivity, average air temperature, atmospheric transfer coefficient, and water vapor as input. Uncertainty in these parameters causes errors in the retrieval of land surface temperature. This study aimed to compare the accuracy of different methods for estimating atmospheric water vapor in estimating land surface temperature using Landsat 8 images. In this study, atmospheric water vapor was estimated using FLAASH atmospheric correction methods, MODIS sensor images, and SWCVR method. Then, the impact of atmospheric water vapor on land surface temperature accuracy was investigated using the split window and single-channel methods. Validation of Land surface temperature images was performed using cross-validation and ground measurement methods. Therefore, 20 Landsat 8 images related to 2018 and 2019 were used to estimate atmospheric water vapor by the FLAASH atmospheric correction and SWCVR methods, and land surface temperature estimation. MODIS radiance images were used to estimate atmospheric water vapor and the land surface temperature product of this sensor was used for cross-validation. The surface temperature was measured using a thermometer in places with homogeneous cover, for ground-based validation. Results showed that among water vapor estimation methods, the SWCVR method is more suitable for estimating land surface temperature and the split-window method based on the SWCVR method shows the lowest RMSE and MADE at 3.47 and 3.18. Results of RMSE image classification of split-window algorithm based on the SWCVR showed that 1.67% of the area has an error of more than 4 °C and 98% of the study area has less than 4 °C error.
The present study was conducted to improve root, shoots growth, and seedling quality index of milkweed (Calotropis procera) using biopriming bacteria Pseudomonas putida (Trevisan) strain 169. An experiment was performed with two levels of... more
The present study was conducted to improve root, shoots growth, and seedling quality index of milkweed (Calotropis procera) using biopriming bacteria Pseudomonas putida (Trevisan) strain 169. An experiment was performed with two levels of inoculum including control and rhizospheric bacteria and three growth periods of one, two, and three months, using a factorial experiment in a completely randomized design with five replications. Biopriming results showed that seedlings obtained from bacterial priming in one-month, two-month, and three-month periods compared to the control, increased 707.5, 1823.1 and 47.6% in root volume; 654.6, 1798.6 and 40.3% in root area; 270.6, 38.5, and 6.6% in fresh weight of stem and 58.5, 19.3 and 2.5% in seedling height, respectively. The highest value of the quality index was observed in seedlings inoculated with the bacterium in the third month. The results of Pearson correlation showed that the parameters of aerial parts such as height, collar diameter, and stem weight were significantly correlated with each other, except root length and root dry weight. Results revealed that the priming of rhizosphere bacteria used in this study had a positive effect on improving the growth parameters of milkweed seedlings. Therefore, it is suggested that more research be done on the coexistence of rhizosphere bacteria in different plants and the interaction of their effects so that this technique can be used more for plant production and desertification.
Due to the intense and unprincipled changes in land use, it is necessary to detect land cover/use change over time using satellite imageries for sustainable land management. This study aims to monitor land use and land cover changes,... more
Due to the intense and unprincipled changes in land use, it is necessary to detect land cover/use change over time using satellite imageries for sustainable land management. This study aims to monitor land use and land cover changes, model and predict their status in the next 15 years in Jagin plain, Jask coastal desert. In this study, Landsat satellite images of 1987, 2003 and 2018 were used to detect changes. After applying geometric and atmospheric corrections on the images, land use maps of each year at 11 land use /land cover classes including farmlands, aquaculture, erg, halophyte, mangrove, habitable zones, nebka, vegetation affected by water flow vegetation (rangeland), bare lands, were prepared using hybrid classification method. The Markov chain forecasting model was used to validate the model in the first stage, and was used in the second stage to predict land cover/land change in 2033. Comparison of the simulated map of 2018 and the real map with the Kappa coefficient of 83% confirmed the capability of the Cellular Automata Markov Chain in predicting of land cover/land changes. According to the results, in 2032, agriculture lands in the region will have an upward trend and grow by 74% compared to 2018. Habitable zones, marine access network and aquaculture lands will also increase during the study period. In the study area, vegetation and riverbed vegetation areas show a downward trend and will mainly converted to agricultural lands. Sand dunes, which are among the main threats to people and mangrove forests, will be extended by 2032, threatening the southern part of Sorglam village and the eastern part of the mangrove forest.
Haloxylon planting and developing artificial forests in arid lands is one of the important actions to combat desertification. In this research, tree planting (by Haloxylon aphyllum Iljin) in Dosangi Meybod in different methods including... more
Haloxylon planting and developing artificial forests in arid lands is one of the important actions to combat desertification. In this research, tree planting (by Haloxylon aphyllum Iljin) in Dosangi Meybod in different methods including repairing, runoff control, pitting and planting in owed have been compared with control area. For this purpose, in each area, four 300 m transects were considered randomly - systematically, and 15 plots (10 m2) were randomly collected on each transect. In each plot, vegetation characteristics including total vegetation percentage, density, canopy cover, freshness and depth of root and soil characteristics including moisture, permeability and soil carbon storage were measured. The Shapiro-Wilk test were used to test of normality of the collected data, and were analyzed using one-way analysis of variance and Duncan's test. According to the results of analysis of variance, the effect of planting with different methods on crown cover, density, freshness and deep rooting of Haloxylon shrubs and the percentage of vegetation is significant at 1% level. However, its effect on permeability and soil moisture in May is significant at 1% level and on carbon storage is significant at 5% level. Increase of vegetation cover by 5.1%, density of 249.7 number per hectare, Haloxylon cover of 3.7%, freshness class 1.5, soil moisture in spring 38.1% rooting more than 3 m and permeability 8.03 cm/h was related to the planting in dry river, which had a relative success in vegetation development in this region.
One of the effective methods to increase crop production in arid and desert regions of the country are some mechanisms increasing plant resistance such as seed priming. A field experiment was conducted on a farm located in Jolgeh Shah... more
One of the effective methods to increase crop production in arid and desert regions of the country are some mechanisms increasing plant resistance such as seed priming. A field experiment was conducted on a farm located in Jolgeh Shah Hashem, Dalgan, with a desert and arid climate, in 2017-2018. This research was carried out as a split-plot experiment in a randomized complete block design with three replications. Experimental treatments consisted of four drought stress levels of irrigation at field capacity "no stress"; irrigation at 75 % of field capacity "moderate stress"; and irrigation at 50 % of field capacity "severe stress"; as main plots, and four seeds priming levels of no priming; hydropriming; Osmopriming with polyethylene glycol; and hormonal priming with salicylic acid as subplots. Results showed that seed priming reduced the number of days to plant germination compared to non-priming treatment. Among prime treatments, hydroprim had the fastest seed germination time after sowing. On the other hand, stress and prime treatments caused early maturity of the plant and among the above treatments, the shortest day to ripening was obtained from severe stress and hydroprime treatment. The highest values of the fresh and dry weight of the plant, fresh and dry sepals of Roselle were obtained from no stress treatment and seed priming at all levels of hydropriming, osmopriming, and hormonal priming. Comparing the above three treatments, it can be concluded that the seed priming with salicylic acid achieved better results than other treatments in no stress conditions. It was also observed for the traits of anthocyanin and sepal phenolic compounds that with increasing stress intensity, the content of these compounds increased in sepals.
Wind erosion and sand dunes mobility has adverse environmental consequences. Identification of factors affecting sand dunes mobility and predicting their future status is essential to control the desertification process. Therefore, in the... more
Wind erosion and sand dunes mobility has adverse environmental consequences. Identification of factors affecting sand dunes mobility and predicting their future status is essential to control the desertification process. Therefore, in the present study, the mobility of flowing sands in the southeast of Qazvin province has been studied and analyzed. For this purpose, hourly wind speed data, dust phenomenon code, rainfall and temperature of Buin Zahra station were used for the statistical period of 2006-2006. Rainfall and temperature data were used to calculate the rate
of evapotranspiration Thornthwaite method. After calculating the percentage of erosive winds and aridity index, by using Lancaster index, the mobility of flowing sand in the southeast of Qazvin province was investigated and analyzed. Sensitivity analysis test was used to predict the effect of climate change on mobility of sand dunes. Results showed that sand dunes mobility was inactive in previous years and activated in recent years. Examining the relationship between the number of dusty days and the Lancaster index using two-variable linear regression showed
that there was no strong and significant relationship in the study period between these two parameters, while a significant relationship between Lancaster index and aridity index. These results indicate that 42% of the changes in the Lancaster index were due to changes of the aridity index. The results of the sensitivity analysis showed that if the average of the wind speed and evapotranspiration rate increased by 30% in future, or amount of precipitation decreased by 30%, the status of the sand dunes mobility would change from inactive to active and crossing this threshold could be the reforming of wind erosion activities in the area.
of evapotranspiration Thornthwaite method. After calculating the percentage of erosive winds and aridity index, by using Lancaster index, the mobility of flowing sand in the southeast of Qazvin province was investigated and analyzed. Sensitivity analysis test was used to predict the effect of climate change on mobility of sand dunes. Results showed that sand dunes mobility was inactive in previous years and activated in recent years. Examining the relationship between the number of dusty days and the Lancaster index using two-variable linear regression showed
that there was no strong and significant relationship in the study period between these two parameters, while a significant relationship between Lancaster index and aridity index. These results indicate that 42% of the changes in the Lancaster index were due to changes of the aridity index. The results of the sensitivity analysis showed that if the average of the wind speed and evapotranspiration rate increased by 30% in future, or amount of precipitation decreased by 30%, the status of the sand dunes mobility would change from inactive to active and crossing this threshold could be the reforming of wind erosion activities in the area.
In this study, the average climate data of meteorological stations including temperatures of the warmest and coldest months of the year, precipitation regime, potential evapotranspiration and UNEP aridity index has been used to map Iran's... more
In this study, the average climate data of meteorological stations including temperatures of the warmest and coldest months of the year, precipitation regime, potential evapotranspiration and UNEP aridity index has been used to map Iran's climate zones. In this regard, climate variable of air temperature, relative humidity, potential evapotranspiration, and recipitation characteristics of 303 meteorological stations throughout Iran was used on monthly and annual time’s scales. The annual aridity index in each site was calculated using the United Nations Environment Program (UNEP) index. Then, the temperature characteristics of the warmest and coldest months of the year were coded. Results show a very high climatic diversity throughout Iran. In this model, Iran's climate was divided into 27 categories. Based on aridity index, Iran has seven climates zones. There are 30 cities with hyper-arid climate. This climate type has three climate territories and occupies about 3.4 percent of the country's territory. The arid zone with five climate territories cover about 23.7 percent of the country and dominates 95 cities. The semi-arid climate with 6 climatic territories accounts for about 39.6 percent and dominates 113 cities. The dry sub-humid zone with four climate territories and covers about 17.3 percent and dominates 30 cities. Nine cities have a semi-humid climate with three climatic territories which accounts for about 8.9%. The humid climate with four climate territories covers about 5.8 % and dominates 13 cities. The very humid climate with 2 climatic territories accounts for about 1.3% and represents the climate type of the 12 cities.
Road networks as an integral part of the transportation infrastructure have deleterious ecological effects on habitats and wildlife populations. Vicinity impacts of road networks on habitats together with habitat fragmentation have caused... more
Road networks as an integral part of the transportation infrastructure have deleterious ecological effects on habitats and wildlife populations. Vicinity impacts of road networks on habitats together with habitat fragmentation have caused decrease in habitat quality, biodiversity decline. Road networks development is one of the most important risk elements for valuable habitats and species of the Chaharmahal & Bakhtiari province. So, it is necessary to evaluate habitat’s condition and ecosystem services into conservation systematic planning and minimizing its negative impacts. For this purpose, first, the habitat quality of Ovis orientalis Gmelin, (subspecies isphahanica Nasonov), Panthera pardus Pocock, and Ursus arctos Linnaeus, were modeled using Integrated Valuation of Environmental Services and Tradeoffs (InVEST). Then, the vicinity impacts of road networks was assessed using the Vicinity Impact index. To assess the efficiency of the current protected areas network and identifying the priority areas for conservation the Marxan software was used. Results revealed that a large area of the Ch & B province were considered as the suitable habitats for target species. However, high density of the road networks affect 14% of the Ch & B ares which increased the impotance of identifying the prioirity areas in terms of high ecological values and low vicinity impact. The results also showed that eastern, western, and southwestern parts of the province have high ecological values and low vicinity impact. Approximately, 28% of these areas are currently protected which showed the relative efficiency of the current protected areas network.
In order to increase efficiency and prevent the waste of limited capitals of combating desertification projects, there is always no a way that could consider different criteria, strategies and among them, based on a systematic structure... more
In order to increase efficiency and prevent the waste of limited capitals of combating desertification projects, there is always no a way that could consider different criteria, strategies and among them, based on a systematic structure and group perspective, offers the optimal solution. The aim of this study was to present a method to rank the optimal strategies to combat desertification in the Yazd-Khezrabad plain based on Multiple Attribute Decision Making model (MADM) using Linear Programming Techniques for Multidimensional Analysis of Preferences (LINMAP) model. In this method, by finding the Euclidean distance of the strategies with the best strategy, the most preferred strategy was selected. In this regard, the problem was transformed into a linear mathematical model, which after running the model in the LINGO software environment, the weight of each strategy, the distance from the ideal strategy and the ideal strategy were estimated. From a LINMAP evaluation model perspective, based on the preference results of five criteria surveyed including Environmental compatibility (C7), environmental and human resource degradation (C16), specialized human resources (C6),
scientific and technological tools (C5) and time (C2), the strategies of vegetation regeneration and rehabilitation " (A23), "prevention of inappropriate land uses change" (A18) and "adjustment in groundwater abstraction" (A31) with a distance of 16.20, 16.22 and 16.35 were selected as the most important strategies to combat desertification in the region, respectively. The results of present study enable the desert managers to utilize limited resources and budget dedicated to control desertification process in a correct and efficient manner. Therefore, the results of the mentioned ranking can increase the success rate of combating desertification and land reclamation projects in the study area
scientific and technological tools (C5) and time (C2), the strategies of vegetation regeneration and rehabilitation " (A23), "prevention of inappropriate land uses change" (A18) and "adjustment in groundwater abstraction" (A31) with a distance of 16.20, 16.22 and 16.35 were selected as the most important strategies to combat desertification in the region, respectively. The results of present study enable the desert managers to utilize limited resources and budget dedicated to control desertification process in a correct and efficient manner. Therefore, the results of the mentioned ranking can increase the success rate of combating desertification and land reclamation projects in the study area
Human societies are considered as a part of ecosystems. The interaction between human societies and ecosystems has consequences for them. Desert ecosystem is one of the common ecosystems in arid regions of Iran. In desert, phenomena such... more
Human societies are considered as a part of ecosystems. The interaction between human societies and ecosystems has consequences for them. Desert ecosystem is one of the common ecosystems in arid regions of Iran. In desert, phenomena such as drought affect the lives of human societies .The present study analyzes the effect of hydrological drought on resilience of human communities in Yazd province. Hydrological drought was studied based on river flow index and resilience of human communities using economic, social and environmental criteria by using principal component analysis method. The factor was calculated based on the values of the rotated matrix and the eigenvector values .Multiple linear regression analysis of drought effects on factors was investigated. Analysis of the relationship between drought and resilience indicates a significant relationship between them. The most affected sectors by drought were economic, social and environmental, respectively. The most important economic losses were the variables of employment share in services and industry sectors, rural income and cost, irrigated agriculture, area under cultivation, urban cost, participatory economy rate. The overall results of combining the drought index with socio-economic and environmental indicators indicate an increase in vulnerability and a decrease in the resilience of human societies due to drought. Lifestyle and direct dependence on ecosystem resources should be reconsidered. In other words, generating processing, conversion and complementary industries, extends the chain of drought dependence and exploitation to reduce drought fluctuations. Diversifying the use of ecosystem services and replacing them in times of drought events can increase the resiliency of human societies.
Surface soil moisture is one of the important variables in hydrological processes that affects the exchange of water and energy flow in relationship between land surface and atmosphere. Precise assessment of spatial and temporal... more
Surface soil moisture is one of the important variables in hydrological processes that affects the exchange of water and energy flow in relationship between land surface and atmosphere. Precise assessment of spatial and temporal variations in soil moisture is crucial for numerous environmental studies. Recent technological advances in satellite remote sensing indicates that the soil moisture can be measured using remote sensing methods. The purpose of this study is to estimate biophysical indices and evapotranspiration using SEBAL algorithm and to present soil moisture index using principal component regression method in the east of Bakhtegan Lake,Fars province. For this purpose, five Landsat 8 satellite images for March, April, May and June 2017 were selected and initially corrected. Meteorological data of Marvdasht synoptic station was used to execute SEBAL algorithm. Soil moisture index was modeled using biophysical indices such as albedo, net radiation flux, soil heat flux, evapotranspiration, and etc. by using principal component regression. TVDI index was used to validate the model. The coefficient of determination (R2) and F index are equal to 0.966 and 1651581.9, respectively, which indicates the high efficiency of the model to obtain soil moisture index for each pixel in different areas with different conditions and diverse vegetation. In addition to temperature and vegetation, other biophysical indicates of the region that affect the soil moisture should be taken into account.
The aim of this study is to evaluate the land cover changes in the basin of Sefiddasht-Borujen using remote sensing Using remote sensing data, land cover maps of satellite images of 1998, 2009, and 2018 were prepared and classified. Then,... more
The aim of this study is to evaluate the land cover changes in the basin of Sefiddasht-Borujen using remote sensing Using remote sensing data, land cover maps of satellite images of 1998, 2009, and 2018 were prepared and classified. Then, using the image differencing method, land cover changes for the time periods of 1998 to 2018 were detected. Finally, predicted land cover changes were investigated in each land cover using a CA-Markov model. To predict the probable changes for the year of 2028, the 2018 land cover was modeled using 1998-2009 images by applying of the CA-Markov method of change detection. Next, the resulted of modeled 2018 land cover map were compared with the ground truth map of this year. The results of both maps showed relatively similarity and there was a slight difference between these predicted and classified images of 2018. Therefore, this method was used to predict 2028 land cover image too. The results of change detection for the years 1998 to 2018 indicates the reduction of 8339 hectares of agricultural lands in the study area, as well as 11824 ha from rangelands. Conversely, the bare land increased 14601 ha. According to predicted map for 2028, the largest incremental change in the bare land will be 16476 ha. Estimates show that 8664 hectares of these lands will be from agricultural lands, but approximately 8580 ha will be transformed into the bare land and about 224 ha to residential-industrial lands. Rangelands also will be reduced by13055 ha including 11663 ha to bare land and 1069 ha will be transformed into residential-industrial areas. 16476 ha will be added to bare land and 1420 ha to residential-industrial areas. The results of the present study can be used for future planning for the study area
Rising atmospheric carbon dioxide is one of the main causes of climate change and its devastating environmental consequences, such as global warming. Soils are the third largest carbon storehouse, and the amount of carbon storage is... more
Rising atmospheric carbon dioxide is one of the main causes of climate change and its devastating environmental consequences, such as global warming. Soils are the third largest carbon storehouse, and the amount of carbon storage is strongly influenced by the land use management. The aim of this study was to investigate the changes in carbon storage in different land uses included Punica granatum orchard, Medicago sativa farm, rangeland, Hordeum vulgare farm and fallow, under impact of soil properties such as sand, clay, silt, nitrogen, phosphorus, potassium, organic carbon, pH and EC, in Ala area of Semnan. In the selected land uses 30 soil samples were taken in both 0 - 5 and 5 - 30 cm soil depths in three. In order to investigate the effect of land use type in two soil depths studied on soil carbon content, analysis of variance and Duncan's test was used to compare the means. Pearson correlation was used to investigate the relationship between soil properties as independent variables and soil organic carbon as a dependent variable. Also, multiple regression analysis was performed to determine relationship type between the variables. According to the results, the type of land use in both soil depths has a significant effect on soil carbon storage. The highest average soil carbon storage in 0 - 5 and 5 - 30 cm soil depths in alfalfa and pomegranate orchard land uses are 16.14 and 68.11 t/ha, respectively. The lowest amount of carbon storage in 0 - 5 and 5 to 30 cm soil depths related to rangeland use are 6.23 and 16.58 hectare/ha, respectively. Pearson correlation coefficient between organic carbon and soil factors of nitrogen and phosphorus were statistically significant with r of 0.8 and 0.59, respectively. Since the correlation between organic carbon and phosphorus is low, it was omitted in the regression analysis. Finally, the percentage of soil organic carbon was obtained based on the percentage of soil nitrogen. In general, land use change from pasture to arable land and pomegranate orchard can have a significant effect on increasing soil carbon storage in the study area. Soil properties other than nitrogen have no significant effect on soil organic carbon.
The first character of the desert is lack of water as well as the lack of vegetation. Although the number of plant species in arid lands is very limited, but these species have survived and adapted over the centuries. Due to the... more
The first character of the desert is lack of water as well as the lack of vegetation. Although the number of plant species in arid lands is very limited, but these species have survived and adapted over the centuries. Due to the difficulty of entering Lut desert, during the last one hundred years, no research was done on plant species in Southern Khorasan part. Therefore, during 2017 to 2018, all perennial species in Lut were identified. The results revealed that a total of six species belonging to four genera and three families were identified. Chenopodiaceae with three species, Poaceae with two species and Polygonaceae with one species occupied 50%, 33.3% and 16.66% of the flora of the region, respectively. Stipagrostis and Haloxylon have the highest number of species. Geographical distribution analysis showed that Iran-Turan and Sahara-Sindi species are presented in equal proportions. Haloxylon persicuum Bge. ex Boiss. & Buhes, Haloxylon ammodendron Bunge ex Fenzl and Stipagrostis plumosa Munro ex T. Anderson were distributed in the north and northeast. The highest distribution of Calligonum comosum L'Hér was observed in the west. Although the diversity was very limited and the 18-year droughts have intensified the drought of Calligonum and Haloxylon in many areas of Lut, however, increase in rainfall in 2019 in Lut increased hope for the survival of shrubs and increasing the amount of Stipagrostis species.
Climate change affects severity and duration of drought, peak, magnitude, and frequency of the events in the coming decades. Iran is one of the countries that have suffered the most from drought. Therefore, drought monitoring and... more
Climate change affects severity and duration of drought, peak, magnitude, and frequency of the events in the coming decades. Iran is one of the countries that have suffered the most from drought. Therefore, drought monitoring and forecasting is crucial for drought mitigation and preparedness strategies in future. This study was conducted to evaluate the status of drought characteristics of severity, duration, magnitude, and peak in historical period from1966 to 2015 and future from 2016 to 2050 for 39 synoptic stations in Iran using Standardized Precipitation Index (SPI). Also, for future simulation, the output of the general circulation model of CanESM2 based on two scenarios RCP4.5 and RCP8.5 and the statistical downscaling method of SDSM were used. Results showed that the trend of severity, duration, magnitude, and peak have no any significant trend. The SPI zoning map shows an increase in the historical period but will decrease in the future period under two scenarios. The results of the trend analysis of the severity, duration, and magnitude and peak drought showed that there is no significant trend in the historical and future in Iran. However, most of these characteristics are increasing in the northern, northeastern, western, and southern parts of Iran. Finally, the southern parts of Iran including Hormozgan and Sistan and Baluchestan provinces, the northeastern and western parts of Khorasan Razavi, Golestan, and Azerbaijan provinces will be most vulnerable to climate change. Therefore, the risk of drought in these regions is high and it is necessary to seriously plan for the management of natural resources, and agriculture.
Controlling and managing of seasonal and sudden floods in arid and semi-arid regions, especially in areas where surface water is out of reach is necessary. Flood spreading is one of the best ways to control surface runoff and recharge... more
Controlling and managing of seasonal and sudden floods in arid and semi-arid regions, especially in areas where surface water is out of reach is necessary. Flood spreading is one of the best ways to control surface runoff and recharge groundwater resources. In the present study, the appropriate sites for flood spreading project in border area of Taybad county in Khorasan Razavi province is selected using Boolean logic .For prioritization the suitable locations, TOPSIS and VIKOR multi-criteria decision making methods were used. Firstly, using Boolean logic inappropriate areas based were removed on criteria (slopes greater than 8%, urban area, agriculture and covered pediment). Then, 11 zones were selected as the suitable areas of using TOPSIS and VIKOR models based on the criteria of slope, groundwater quality, geology, alluvium thickness, transmission capability, drainage density, surface permeability, groundwater loss, distance from the village, distance from wells and land use.. Results showed that most suitable areas are located in alluvial fans. Based on the TOPSIS model, location J with value of 0.75 was selected as the best site, and using the VIKOR model, location K with a value of 0.96 was selected as the best location for flood spreading projects.
Climate change is the most important global challenge, particularly in semi-arid regions. The objective of this study was to investigate the effect of changes in climatic parameters on drought and desertification hazard in Kermanshah... more
Climate change is the most important global challenge, particularly in semi-arid regions. The objective of this study was to investigate the effect of changes in climatic parameters on drought and desertification hazard in Kermanshah province, Iran, using precipitation, temperature, evaporation and relative humidity data during period of 1992 and 2018. Desertification risk was assessed through UNEP index. The results of this study showed that during the last decade, climatic elements in Kermanshah province have undergone significant changes. Among all climatic parameters, changes in air temperature were noticeable, so that the maximum, minimum and average temperature at most stations in Kermanshah province has increased significantly. Relative humidity decreased at most stations and precipitation decreased .These changes have been more evident and significant in Kermanshah city than in other parts of the province .The study of SPEI index showed that all part of the provinces impacted by drought and the southwestern areas are facing with more severe drought.The trend of drought changes in Kermanshah province in most parts of the province during the last decade compared to the decades also showed, an increase in the drought intensity and duration and a decrease in the length of wet duration. The desertification risk is observed in north. The highest desertification risk is observed in the southwestern regions of the province, mainly Somar, Naftshar and Ghasreshirin, but the trend of changes only in Kermanshah showed increased desertification risk due to significant changes in climatic elements
In recent years, due to the expansion of industrial activities, the concentration of heavy metals in the environment as well as foods has increased. Heavy metals are dangerous because of their bioaccumulation. Regarding the importance of... more
In recent years, due to the expansion of industrial activities, the concentration of heavy metals in the environment as well as foods has increased. Heavy metals are dangerous because of their bioaccumulation. Regarding the importance of contamination of heavy elements of the soil, the present study aimed to provide the spatial distribution of heavy metals and its relationship with land use in the Yazd-Ardakan plain, Iran. First, 201 soil samples from depths of 0 to 20 cm were sampled using the hypercube method, and the total concentration of iron, manganese, nickel, lead, and zinc elements were determined using Analytical Jena-novAA300 atomic absorption device. Then, to convert point data to surface data, geostatistical methods of IDW, GPI, RBF, LPI, and Kriging were used. The land cover/use map of the Yazd-Ardakan plain in 2016 was mapped using an object-oriented classification method. Results of the relationship between heavy metals concentration and land cover/use showed that the agricultural lands and gardens and sand dunes with the mean of 0.950 and 0.836 ppm had the highest and lowest iron concentrations. The highest mean concentration of manganese was related to the residential land (1.821 ppm) and the lowest mean of rocky terrains (1.083 ppm), the most average for poor rangelands and bare land was (0.302 ppm), Residential areas had the lowest nickel concentration (0.192 ppm). The highest mean of lead metal in agricultural land and gardens, as well as residential areas (1.465 and 1.373 ppm, respectively) and the lowest, mean in rocky terrains (0.925 ppm). Agricultural and gardens areas, and residential lands, have the highest mean of zinc concentration (0.583 and 0.552 ppm, respectively), and the rocky terrain has the lowest zinc concentration (0.342 ppm).
Specific climatic and geographical conditions of Yazd province have always exposed this region to a severe storm, and air pollution. Low visibility is the primary impact of air pollution due to atmospheric phenomena. Increasing dust... more
Specific climatic and geographical conditions of Yazd province have always exposed this region to a severe storm, and air pollution. Low visibility is the primary impact of air pollution due to atmospheric phenomena. Increasing dust density, along with a severe decrease in visibility, has harsh effects on the health of living things, socio-economic sections, and transportation systems. Therefore, identifying hazardous areas considering low visibility during dust events is important to manage and conserve the health of area residents. This study aims to evaluate the trend of changes in horizontal visibility of areas affected by dust storms in Yazd province, Iran. For this purpose, the quantitative model of horizontal visibility based on the relationship between Aerosol Optical Depth (AOD) of MODIS sensor derived from Deep Blue algorithm and horizontal visibility data derived from meteorological stations in the study area was introduced the horizontal visibility of dust events from 2015 to 2017 was mapped using geostatistics Kriging method. Results showed a significant relationship between aerosol optical depth and horizontal visibility data at the 99% level. The AOD value ranges from 0.1 in areas with no dust to 1.9 in areas with severe dust at six studied events, and the visibilities coincide with AOD values from 64 m in dust centers to 19951 m beyond these centers were estimated. Therefore, AOD image measures with more than 0.8 have horizontal visibility less than 1000 m. Determining of horizontal visibility extent without spatial limitation and identification of areas affected dust events are advantages of the quantitative model of horizontal visibility and its mapping. According to land cover/use map in Yazd province, mineral and constructing sites, high-density dirt roads, sand dunes, poor rangelands are the most effective factors in increasing of dust density and low horizontal visibility in pathways of dust storms of this province.
Estimation of the maximum 24-hour precipitation is one of the important parameters in irrigation and drainage projects, design of hydraulic structures, and watershed management. This rainfall data is used to calculate short-term rainfall... more
Estimation of the maximum 24-hour precipitation is one of the important parameters in irrigation and drainage projects, design of hydraulic structures, and watershed management. This rainfall data is used to calculate short-term rainfall and design flood. At-site and regional frequency analysis of the maximum 24-hour precipitation climate projects are essential and can be a positive and efficient step for analyzing the storms and productive floods. In this research, the L-moments approach is used for regional frequency analysis of the maximum 24-hour precipitation of 18 stations in Yazd province. The Ward clustering algorithm is used to identify homogeneous region. The selected stations are classified into two groups, and each region is tested using Hosking and Wallis Homogeneity critter. After ensuring the homogeneity of the regions, by using the goodness of fit test, Generalized Extreme Value distribution is suggested as the best fit distribution in both regions. The parameters of the distribution were calculated by the L-moments method for both regional and at-site approach. The performance of the two approaches was compared using RMSE and RRMSE statistic indices. Comparison of the regional approach with the at-site approach showed that both estimates at short return periods (less than 10 years) are not much different and computational errors are also less. However, there is so much difference at longer return periods. It can be stated that the regional approach in the first and second homogeneity regions (80% and 70%, respectively) is more appropriate rather than the at-site approach for maximum 24-hour precipitation frequency analysis.
Wind erosion is one of the most important processes of land degradation and desertification in arid, and semi-arid areas. Due to lowering of Urmia Lake’s water level, large bare land was created, which makes it crucial to assess their... more
Wind erosion is one of the most important processes of land degradation and desertification in arid, and semi-arid areas. Due to lowering of Urmia Lake’s water level, large bare land was created, which makes it crucial to assess their susceptibility to wind erosion. This research was carried on according to the geomorphological mapping unit (facies), field sampling, and granulometric measurements, as well as threshold wind velocity analysis. Results showed that the facies including saline and puffy lands (19%), inselberg island (13.5%), salt crust dry-river (12.8%), and abandoned lands (10.7%) have been the most frequent land surfaces over the study area, respectively. Granulometric studies showed that the average particle diameter, sorting, and skewness are 870 , 2.91 and -0.15, respectively. Assessment of threshold wind velocity (Vt) according to the Velikanov formula, showed that the highest and lowest value was 18.83 and 8.3 Knots, and the weighted average on the geomorphological facies was estimated 11 knots. The most value of erodibility factor is estimated for the puffy and salty land surface. Although the wind erodibility of the study area is noteworthy, the wind erosion rate cannot be severe due to natural conditions, such as climate and the presence of vegetation. Zonation of soil erodibility showed that the southeastern parts of the Islamic Island and northwest littoral area of Lake Urmia were the most susceptible regions to wind erosion. Evaluation of sand drift potential showed that the highest potential was in Tabriz (DP= 232, UDI= 0.05), Khoi (DP= 130, UDI= 0.49) and Urmia (DP= 63, UDI= 0.59) stations, respectively. Finally, due to lack of sand sources and wind’s energy, the western and northwestern part of the Lake Urmia have more capability for sand dunes formation and wind erosion. However, for salt emission and effecting of the surrounding, lands more research is needed to find out the susceptible area to salt weathering.
Site selection is the first and most important stage in implementation of natural resources management projects. It can be effective in reducing the cost and timing of projects. The underground dam is one of the structures that reservoir... more
Site selection is the first and most important stage in implementation of natural resources management projects. It can be effective in reducing the cost and timing of projects. The underground dam is one of the structures that reservoir is created in the underground, and its extraction depends on the topography and geology conditions of the area, so its location is very important from the hydrological, economic, and social points of view. In this research, the ARAS multi-criteria decision-making model and geographic information system (GIS) were used to select the most suitable sites for the underground dam construction in Kajbid-Balaghli Watershed, Garmah, North Khorasan. First, suitable sites were determined by using an exclusion method based on criteria (stream order, slope, geology, land use, fault, qanat, and spring). To prioritize suitable locations, water quantity criteria, water quality, reservoir slope, reservoir permeability, reservoir depth, reservoir surface, structural height, structural length, anchorage, water requirement, and access to the structures were used to determine the appropriate locations. The relative importance of the criteria was done using AHP method. Finally, the ARAS decision method was used to prioritize the suitable sites. Results showed that the water quantity criterion with relative importance of 0.23 and the criterion of underground dam anchorage with the relative importance of 0.02 gain highest and lowest score in views of the experts, respectively. The most suitable sites for the construction of underground dam was location A with Si = 0.36 and Ki = 1.
Taradeh, Kerman province, has valuable forest stands that are under pressure from local communities. In this study, after making forest survey, plot area was selected as 1500 m2 and 50 samples were collected systematically with in a grid... more
Taradeh, Kerman province, has valuable forest stands that are under pressure from local communities. In this study, after making forest survey, plot area was selected as 1500 m2 and 50 samples were collected systematically with in a grid of 100 m×100 m. In each plot, the plant species were recorded along with diameter at breast height, tree height, crown diameter, number of trees per hectare, large and small crown diameters, regeneration count, the distance between plot center and the nearest tree, and distance to neighboring trees. Results showed that the forests under study are mixed and include Prosopis cineraria, Prosopis farcta, Tamarix stricta, Lysium shawii, and Calligonum comosum as the main species. The mean density of Prosopis cineraria and other species were 10.6 and 37.2 tree.ha-1 and canopy cover were 308 and 1088.3 m`2.ha-1, respectively. The height and diameter of P. cineraria trees were in the range of 5.5-14.3 m and 16-100 cm respectively, and its regeneration density was 1.26 tree.ha-1. The structure of the forest was uneven-aged and two-layered which in overstory was occupied by P. cineraria trees. The distribution pattern of P. cineraria trees was clumped which may be influenced by type and size of the seeds, dispersion method, human interference, habitat constraints, and livestock grazing. Due to the lack of trees in low diameter classes and lack of regeneration, tree planting and preservation is recommended, especially in occupied lands.
One of the most important issues in water resources management in agriculture is determining the plant water requirement by estimating the actual evapotranspiration of the crop. One of the empirical methods for determining the plants and... more
One of the most important issues in water resources management in agriculture is determining the plant water requirement by estimating the actual evapotranspiration of the crop. One of the empirical methods for determining the plants and crops evapotranspiration is the method mentioned in FAO 56's report. One of the main problems of this method is the KC coefficient estimation, especially when the percentage of crop cover, irrigation methods, and other factors in the region varies. The aim of the present study was to estimate the KC and pistachio plant's (Pistacia vera L.) KC-NDVI relationship in different stages of pistachio phenology in Pistachio orchards of Abarkuh desert margin in Yazd province. The KC-NDVI relationship has the main role in plant water management requirements. First, the actual daily evapotranspiration rate over the 16 different periods corresponding to a full pistachio's growth period is calculated. Then, by dividing the actual plant evapotranspiration to evapotranspiration of reference plant on the same day, the Kc maps were created. Finally, the relationship between KC and the NDVI index was obtained. Based on the results, there was a significant correlation between the pistachio plant coefficient and the NDVI index at a 99% level (P-value <0.01). At the beginning and end of the pistachio growth period, the lowest correlation was found between the pistachio plant coefficient and the NDVI index. The highest correlation was observed in the mid-growing season, which is coincident with the peak of heat and evapotranspiration. In general, the pistachio vegetation coefficient is between 0.3 and 0.9 concerning NDVI index in the study area. Relationship between KC and NDVI at the 1)beginning of growth season, 2) development stage, 3) mid-growth stage, and finally 4) harvest season were KC-1 = 1.66 NDVI + 0.261, KC-2 = 1.29 NDVI + 0.338, KC-3 = 2.10 NDVI + 0.147, KC-4 = 1.21 NDVI + 0.231, respectively.
Prolonged drought has resulted in severe wind erosion and dust storms in Sistan region. Investigating wind erosion and dust storms is essential to control these Phenomena. Investigating the vertical distribution of aeolian sediment flux... more
Prolonged drought has resulted in severe wind erosion and dust storms in Sistan region. Investigating wind erosion and dust storms is essential to control these Phenomena. Investigating the vertical distribution of aeolian sediment flux is important for assessing sediment transport, validating wind erosion models, and understanding the mechanism of particle movement. In this study, six dust storm events and vertical distribution of sediment flux within these events were studied during a period of four months of 2018 in Sistan. Recorded diurnal wind speed, visibility, and PM10 data at Zabol meteorological station were obtained for the study period. To obtain a vertical distribution of sediment flux, seven sediment samplers were installed at seven heights from 20- to 700 cm in the Niatak area of Sistan. Results indicated that the six dust storm events have been recognized to be severe, because wind speeds of 16-19 m/s have blown in a long period of the events, visibility was <1000 m most of the time, and PM10 increased >2000 µg m-3 and sometimes >8000| µg m-3. The greatest sediment flux was observed in events 3 and 4 and least in event 3. Sediment flux was attributed to wind speed and durian of blowing wind speed. Sediment flux is greater in higher wind speeds and long events. There was a close relationship between recorded PM10 at Zabol station and collected sediment. There was a negative and power correlation between sediment flux and height.
Gavkhuni wetland has faced numerous changes in its dry and humid surface due to some climatic and human factors in recent decades. This study aims to investigate the role of drought in producing and intensifying dust phenomena in the... more
Gavkhuni wetland has faced numerous changes in its dry and humid surface due to some climatic and human factors in recent decades. This study aims to investigate the role of drought in producing and intensifying dust phenomena in the center and surrounding areas of Gavkhuni wetland. The physical changes of the wetland are first determined using remote sensing and GIS techniques. Then, the number of days with dust is identified using data measured at selected synoptic stations. Results showed that the wetland had its highest moisture level about 89% of the surface of water in 1993, and then there was a gradual decline each year since 1993. It has been more dried so that the wetland water level was less than 10% in 2013 and has been completely dried from 2013 to 2019. The results of the Lancaster index indicate most of the sand dunes in this area have been activated during the study period. Correlation analysis for annual and seasonal dust days at stations around wetland do not show a significant relationship with wetland drying condition in most of the stations. It is statistically significant for Isfahan station in spring and summer at 1%, and in autumn at 5%. However, since the direction of the Isfahan station storms is from west to east in spring and autumn, and the Gavkhuni wetland is located in the east of Isfahan, the relationship cannot be accepted. This relationship is significant for Shahreza station in summer and Aghda station in autumn at a 5% level. The directions of dust storms are from east to west towards Shahreza in summer, and from west to east towards Aqda in autumn. Therefore, increasing the trend of dust production in these two regions and seasons, considering the positive and significant correlation coefficient could be due to the dry surfaces of wetland in recent years.
Mining is considered one of the dimensions of development that human activities affect ecosystems. In land sustainable management (LSM), ecosystem changes that occur in areas during mining -as one of the appropriate measures to determine... more
Mining is considered one of the dimensions of development that human activities affect ecosystems. In land sustainable management (LSM), ecosystem changes that occur in areas during mining -as one of the appropriate measures to determine the ecological vulnerability- is very important. In the present study, based on ecological sustainability, environmental degradation model of Tabas city were evaluated and classified. In this regard, a set of environmental factors including topography, vegetation, climate, groundwater, soil, and geology data layers were prepared using satellite images and stationary data. According to the results, environmental factors of topographic, precipitation, and vegetation have the highest sensitivity, respectively. According to studies, mines accounted for 15.3 percent of the study area. Most exploratory mines were classified in a semi-sensitive class. Soil and geological (edaphic) factors with the highest ecological limitation were more diverse than other factors in this region. Accordingly, due to the high sensitivity of the soil and the possibility of erosion, especially in areas with low vegetation or barren lands in eastern and southwestern areas that have more vulnerable, should be less priority in mining activities.
One of the most important services of mangrove wetland ecosystems Avecennia marina, Forssk. Vierh in addition to protecting the beach from sea waves, reducing fine dust and preventing coastline erosion, is their high visibility feature.... more
One of the most important services of mangrove wetland ecosystems Avecennia marina, Forssk. Vierh in addition to protecting the beach from sea waves, reducing fine dust and preventing coastline erosion, is their high visibility feature. The present study was down in the framework of the FAO instruction to determine the land evaluation. The method limitations of conditions in the situation and quality of the land were used to combine degrees of merit to identify the environmental factors include strengths, weaknesses, opportunities, threat, prioritize factors, providing solutions, and strategy with the aim of developing sustainable tourism in the area. For this purpose, matrix assessment internal factors (IFE), evaluation of external factors (EFE) and matrix strategy formulation were used. Finally, the strategies were prioritized according to the results of the QSPM matrix (strategic quantitative evaluation matrix). Results show that about 61.1% of the area has S1 class and appropriate tourism and 18 % of the Koleghan basin in the S3 class and has merit low for tourism, 12.48% in the N class with the lack of merit for tourism and finally the S2 class with an area of equivalent to 8.45% of average merit of tourist up give. Temperature, soil, elevation, access paths, distance to city and welfare facilities are factors enhancing merit area study for tourism. The results obtained in the other method show that in the Koleghan basin, 10 parameters were identified as strengths, with a mean score of 0.618 and 6 parameters identified as a threat If we use the capacity of the strength and efforts to addressing the threat factors, this area with Avecennia marina, Forssk. Vierh ecosystem will create a very good tourism opportunity.
Functional traits of plant species are displayed ecological properties, life strategy, and species ability for an encounter with a special environment. In this study, seven elevation points with 50 m interval with 1500 to 2002 m distance... more
Functional traits of plant species are displayed ecological properties, life strategy, and species ability for an encounter with a special environment. In this study, seven elevation points with 50 m interval with 1500 to 2002 m distance on the ground were selected and each point, 10 plots were established along a transect perpendicular on slope. To investigate the function of plant species groups, six functional traits including plant height, growth form, life form, reproduction type, life span, and type of nitrogen fixation were measured or collected. Functional plant species groups and five functional diversity indices were extracted using FDivesity software. The ANOVA test was done to investigate the effect of elevation on functional traits. Results show that elevation had significant effect on Rao index and functional divergence and there was no significant effect on other indices. Compare of means frequency and plant height was shown that there is significant difference between two functional groups. Results indicate that functional traits provide a suitable tool for studying and understanding environmental changes.
Haloxylon salicornicum (Moq.) Bunge ex Boiss and Haloxylon aphyllum Iljin are two important halophytes in desert. Hammada salicornicum and Haloxylon aphyllum Iljin have grown extensively in playa and sand dunes and are essential for... more
Haloxylon salicornicum (Moq.) Bunge ex Boiss and Haloxylon aphyllum Iljin are two important halophytes in desert. Hammada salicornicum and Haloxylon aphyllum Iljin have grown extensively in playa and sand dunes and are essential for supplying of forage for livestock, especially camels. The present study investigated the effects of different soil conditions in two areas (soil saline-sodic of playa and sandy soil in erg), on antioxidant activity, pigments characteristics, total phenolics, glycine and glutamine. The results showed that the highest amounts of chlorophyll a and total chlorophyll were measured 4.35 and 5.72 mgg-1fw in H. aphyllum and playa habitats, respectively. The highest amounts of chlorophyll b with 2.85 mg/g fresh weight were measured in H. salicornicum in playa habitats. The amount of anthocyanin was double in the playa habitats and was more than these two plants. The highest amounts of phenol with 458.97 mg/g fresh weight was measured in playa habitats and in H. aphyllum with 469.53 mg/g fresh weight. The amounts of antioxidant activity in playa habitats and H. aphyllum were significantly more than the erg habitat H. Salicornicum. Glutamine was not significantly different between the two habitats. The highest amounts of glycine betaine were measured in sandy habitats in H. Salicornicum. H. Salicornicum and H. aphyllum known as halophytes can be countered salinity by various mechanisms, such as improving their biochemical conditions, and thus improving the quality of forage and increasing the foliage preference value.
Rainfall is one of the most important environmental factors affecting the density and canopy cover percentage of plant species, erosion, and natural hazard status and its measurement is important for achieving appropriate water... more
Rainfall is one of the most important environmental factors affecting the density and canopy cover percentage of plant species, erosion, and natural hazard status and its measurement is important for achieving appropriate water management. Satellite products have been introduced as an alternative method for ground-based measurements due to inaccessibility of some areas such as arid, semi-arid and mountainous areas and lack of temporal and spatial rainfall data. This study aimed to investigate the efficiency of PERSIANN and PERSIANN-CDR satellite products to measure monthly and annual rainfall in Chaharmahal and Bakhtiari province in time span of 2010 and 2016, using correlation coefficient, root means square error and relative bias. Results showed that PERSIANN-CDR yielded the highest correlation coefficient, lowest RMSE and lowest relative bias in both monthly and annual scales. Estimations of rainfall by both PERSIANN and PERSIANN-CDR products were more accurate in monthly scale compared to annual scale. The correlation coefficient of PERSIANN monthly and annual rainfall respectively were 0.833 and 0.465. These correlations for PERSIANN-CDR were 0.877 and 0.641, and statistically significant for monthly and annual rainfall data, respectively. Due to limited numbers of rainfall gauges and inappropriate distribution and their importance in watershed runoff studies, drought and vegetation studies, and using satellite rainfall products with high spatial and temporal coverage can be considered as a suitable data source in climate studies, especially in arid and semi-arid regions of Iran.
Quantitative description of valley profiles can be used to identify its geomorphologic and dynamic properties and a useful tool in separating of the valleys created by various processes. In this study, the longitudinal and cross-sections... more
Quantitative description of valley profiles can be used to identify its geomorphologic and dynamic properties and a useful tool in separating of the valleys created by various processes. In this study, the longitudinal and cross-sections of 15 valleys were investigated in three geological formations of Kahar, Taft and Granite. Fractal properties of valleys along with the mathematical functions and two Vf and Fr indices were used to study valley morphology. The average of Vf index was calculated in Kahar, Taft and Granit formations 5.56, 3.52 and 1.38, respectively. The average of Fr index in three formations were calculated 0.07, 0.20, and 0.17, respectively. Results indicated heterogeneity in the lithology and structural of valleys. According to the results, the shape of the valley, from Kahar to Taft formation, is U profile to V-shaped profile. The results showed that less curvature profiles are fitted with linear functions and profiles with more curvature fitted with polynomial functions. In fact, the polynomial functions, especially, fourth order, have high ability in modeling longitudinal and cross-sections of the valleys. Subsequently, multifractal analysis of cross-sectional valley, using the general multi-fractal dimensions (Dq) and the technical spectrum f (αq), showed that these sections are transmitted from monofractal to multi-fractal. None of the valley sections in Taft formation has multi-fractal properties. In a number of cross-section valleys of Granite and Kahar formations, the multifractal approach seems to be more appropriate, because of varying of fractal parameters depending on the locations. The results of this study showed that the multifractal analysis is a useful tool for assessing the complexity of cross-sections of the valleys and explaining hydrological and geomorphologic properties of valley and watershed.
Zehkalut in Jiroft, is one of the arid lands in the country, has been facing desertification problem in recent years, due to the improper exploitation of natural resources. As desertification has become a serious problem in this region,... more
Zehkalut in Jiroft, is one of the arid lands in the country, has been facing desertification problem in recent years, due to the improper exploitation of natural resources. As desertification has become a serious problem in this region, it seems necessary to use models for rehabilitation and biological restoration of the degraded areas, based on environmental conditions and ecological potential. The main aim of this study is to provide a model to determine an appropriate method of reclamation and rehabilitation of desert (desertification) considering all environmental factors for successful implementation of projects. A model for desert reclamation using Fuzzy Analytical Hierarchy Process (FAHP) model has offered in this research. For this purpose, opinions of experts to determine the effective criteria and their priorities were evaluated by using Delphi method and pairwise comparisons. Then, by developing Fuzzy decision-making matrix and using weighted linear combination method, the coefficient of significance of the criteria was determined. Final land suitability map for land reclamation of the area was produced by applying the coefficient of significance of each criterion to the classified map of the same criterion and integrating the maps using a fuzzy gamma operator. Results showed that reclamation of degraded areas could be done only in margins of the watercourses by planting compatible and native tree species. This area include the lands that are predicted to be used with the utmost caution in biological operations, to justify the costs incurred. The results show the ability of the Fuzzy Analytical Hierarchy Process and GIS in assessing land suitability for reclamation considering a group decision-making approach.
To comparison biomass production, accumulation of some elements and ash content of shoots in five halophytes species including Salicornia bigelovii Torr., S. sinus persica, Atriplex lentiformis Torr., Halocnemum strobilaceum Bieb., and... more
To comparison biomass production, accumulation of some elements and ash content of shoots in five halophytes species including Salicornia bigelovii Torr., S. sinus persica, Atriplex lentiformis Torr., Halocnemum strobilaceum Bieb., and Halostachys caspica Botsch irrigated with seawater, a research was conducted at Salinity Research Station in Bushehr province. The results showed that there was a significant difference between the halophytes species in terms of concentration of Na+, K+, Cl-, Na+/K+ ratio, fresh weight, dry weight, shoot water content and ash. The highest and lowest Na+ concentrations were obtained in S. sinus persica and A. lentiformis species, respectively, whereas the rate of shoot Na+ in S. sinus persica was more than A. lentiformis by 101.3%. The highest concentration of K+, Cland Na+/K+ were obtained in leaves of A. lentiformis and shoots of two species of Salicornia and H. strobilaceum species, respectively. A. lentiformis with the production of 18.98 and 7.75 ton ha-1, had the highest fresh and dry biomass, respectively. The lowest fresh and dry biomass were also found in S. bigelovii by 10.13 and 2.49 ton ha-1, respectively. The highest and lowest ash content were related to shoots of S. sinus persica equal to 48.8% and leaves of Atriplex lentiformis equal to 37.5%, respectively. According to the results, Salicornia species has no mechanism of preventing salt entrance in the plant due to high concentration of Na+ and Clions in their shoots. These species follow the mechanism of salt accumulation in plant tissues with the aim of osmotic regulation for survival in high saline conditions. Atriplex lentiformis also produced the highest amount of biomass, which could attributed to the low shoot water content of this species due to the presence of hard stems in the plant in comparison to the succulent stems and higher shoots water content in the other species. According to the production amount and ash content, it seems that A. lentiformis is a suitable species for forage producing in the regions with limited freshwater. Furthermore, Salicornia species could be also considered as part of a livestock diet in this regions.
Investigation of spatial variability of maximum 24-hour rainfall is very important for assessment of water resources and forecasting of natural disasters. In this research, the most appropriate probability distribution to estimate the... more
Investigation of spatial variability of maximum 24-hour rainfall is very important for assessment of water resources and forecasting of natural disasters. In this research, the most appropriate probability distribution to estimate the maximum daily rainfall in return periods of 2, 5, 25, 50 and 100 years using Easyfit software based on Kolmogorov-Smirnov test is Wakeby distribution. Wakeby distribution was fitted to maximum daily rainfall. Semi-variogram values for mentioned return periods were calculated and plotted using simple kriging method and were fitted to an appropriate model. Then Maps of isohyetal line were drawn for different return periods. Results of semi-variogram showed that fitted model to variogram of the maximum 24-hour rainfall in return periods of 2, 5, and 25 is Gaussian and in return periods of 50 and 100 is spherical distribution. Suitability of variogram model was evaluated with cross validation method and calculating ME and RMSE statistics. RMSE criteria was obtained less than %40 for all of return periods that shows the accuracy of estimatings. Simple kriging method is suitable for zonation of the maximum daily rainfall. Central Iran in all of the produced maps have lowest daily rainfall than other regions. Reason of differences in maps at different return periods is differences of rainfall values in mentioned return periods. In the other hand, homogeneous areas are closer to each other in terms of rainfall amounts in a return period.
In arid and semi-arid regions, trees have a great influence on distribution of soil nutrient elements and biochemical processes. Considering the capabilities of Tamarix ramosissimia Ledeb shrub in affecting soil properties,... more
In arid and semi-arid regions, trees have a great influence on distribution of soil nutrient
elements and biochemical processes. Considering the capabilities of Tamarix ramosissimia
Ledeb shrub in affecting soil properties, identification and management of this shrub will be important in deserts of Iran. The aim of this study was to investigate the effect of Tamarix shrub on soil physical and chemical properties and carbon sequestration in Farokhabad desert region of Dehloran. In order to study soil characteristics, soil sampling carried out from topsoil 0-5 cm and subsoil 5-20 cm under canopy cover and open area by using systematic randomized method. In this research, soil chemical parameters including organic matter percentage, carbon sequestration amount, pH, EC, N, P, K, CEC, CaCO3, and CaSO4 and soil physical parameters including texture, BD ،BP, ،FC, PWP, and SP were measured. Results showed that there was significant difference at 1% probability level among soil properties such as soil carbon sequestration, organic matter, pH, EC, CEC, N concentration and CaSO4 percentage between under canopy and open area and even in different soil depths. The results of stepwise regression showed that pH, silt and K are one of the most important components affecting the amount of carbon sequestration in the soil under the canopy of Tamarix shrub. In general, climate condition of the study area is suitable for Tamarix shrub which has a positive effect on soil properties by increasing organic matter and improvement of soil structure. As well as, Tamarix shrub increased soil fertility by increasing nutrient elements of soil, hence protection and reclamation of this species is essential for Ilam province.
elements and biochemical processes. Considering the capabilities of Tamarix ramosissimia
Ledeb shrub in affecting soil properties, identification and management of this shrub will be important in deserts of Iran. The aim of this study was to investigate the effect of Tamarix shrub on soil physical and chemical properties and carbon sequestration in Farokhabad desert region of Dehloran. In order to study soil characteristics, soil sampling carried out from topsoil 0-5 cm and subsoil 5-20 cm under canopy cover and open area by using systematic randomized method. In this research, soil chemical parameters including organic matter percentage, carbon sequestration amount, pH, EC, N, P, K, CEC, CaCO3, and CaSO4 and soil physical parameters including texture, BD ،BP, ،FC, PWP, and SP were measured. Results showed that there was significant difference at 1% probability level among soil properties such as soil carbon sequestration, organic matter, pH, EC, CEC, N concentration and CaSO4 percentage between under canopy and open area and even in different soil depths. The results of stepwise regression showed that pH, silt and K are one of the most important components affecting the amount of carbon sequestration in the soil under the canopy of Tamarix shrub. In general, climate condition of the study area is suitable for Tamarix shrub which has a positive effect on soil properties by increasing organic matter and improvement of soil structure. As well as, Tamarix shrub increased soil fertility by increasing nutrient elements of soil, hence protection and reclamation of this species is essential for Ilam province.
Drought is one of the most important environmental stresses that affects plant morphology and physiology. The present study was carried out to measure some physiological indices of four drought resistance trees at Isfahan University of... more
Drought is one of the most important environmental stresses that affects plant morphology and physiology. The present study was carried out to measure some physiological indices of four drought resistance trees at Isfahan University of Technology and aimed at managing desert. Physiological parameters of Ailanthus altissima, Robinia pseudoacacia, Morus alba and Melia azedarach including leaf water potential using pressure bomb, stomatal conductance through hand-held Porometer and chlorophyll content using SPAD were measured before and after irrigation. Data analysis and comparison of means was performed using SPSS 22.0 software, dependent T-Test. The results that showed that drought stress significantly reduced the leaf water potential by 11.56, 16.3, 14.54 and 13.54 bar as well as the stomatal conductance by 6.93, 5.42, 6.39 and 9.98 mmol m-2s-1 after irrigation for Robinia pseudoacacia, Ailanthus altissima, Melia azedarach and Morus alba, respectively. The chlorophyll content was also decreased by 1.5, 2.83, 2.16 and 2.24 mg g-1 after irrigation for Robinia pseudoacacia, Ailanthus altissima, Melia azedarach and Morus alba, respectively, but this was not statistically significant (P>0.05). According to the physiological responses of the trees, it can be concluded that Robinia pseudoacacia, Ailanthus altissima, Melia azedarach and Morus alba are drought resistance trees, respectively that are recommended in arid areas.
The purpose of this study was to evaluate soil erosion in the present period and to predict soil erosion potential under the impact of climate change over time horizon of 2030. Daily rainfall data and NCEP data during 1985-2015 were used.... more
The purpose of this study was to evaluate soil erosion in the present period and to predict soil erosion potential under the impact of climate change over time horizon of 2030. Daily rainfall data and NCEP data during 1985-2015 were used. The future climate was projected using the second generation earth system model (CanESM2) and downscaled using the SDSM model under RCP2.6, RCP4.5, and RCP8.5 scenarios. Rainfall erosivity (R-factor) was estimated for different scenarios and soil erosion were simulated using RUSLE 3D. Results showed that rainfall increases from 146.7 to 178.61 mm in the future and R-factor increases from 28.7 to 34.33 MJ mm ha-1 y-1, respectively. However, due to increasing rainfall intensity in all scenarios and stations, the amount of rainfall erosivity in the future is more than the baseline period. The amount of soil erosion is estimated 10.16 ton ha-1 y-1 at baseline period. Considering the constant assumption of other variables in the RUSLE 3D model and the increase in future rainfall erosivity, the erosion rate under RCP2.6 scenarios increased to 15%, RCP4.5 to 10% and RCP8.5 to 3%, respectively. Accordingly, the increase of rainfall increases the rainfall erosivity factor and consequently increases the erosion rate. Therefore, assessing the present and predicting future soil erosion in the Minab Esteglal dam watershed, provides useful information for environmental and soil conservation.
The milkweed shrub, in addition to ecological functions, has special industrial and medicinal values. This plant is widely planted for afforestation in arid lands in the south of Iran. Regard to scarcity of fresh water, using of seawater... more
The milkweed shrub, in addition to ecological functions, has special industrial and medicinal values. This plant is widely planted for afforestation in arid lands in the south of Iran. Regard to scarcity of fresh water, using of seawater as a vital and alternative source of water for irrigating of halophyte plants was suggested. Thus, the current research was carried out to investigate the efficiency of diluted seawater on seed germination, growth and physiology parameters of milkweed seedling. For this purpose, an experiment was conducted in completely randomized design with three replications in two separate experiments; in vitro and nursery, with different levels of diluted seawater i.e. 0, 12.5, 25 and 50% using saline meter. The results of seed germination test showed that germination parameters and seed vigor index significantly decreased by increasing seawater concentration to more than 12.5%. The results of nursery experiment revealed that concentrations of more than 25% of seawater significantly reduced growth performance and gas exchange of seedling. The survival rate 55%, height 19.9 cm, specific leaf area 190.7 g/cm2 and root length 22.54 cm as well as photosynthesis rate 2.83 µmol, transpiration rate 0.42 mmol, chlorophyll 20.45% and relative water content 43.95% were observed in 25% seawater treatments. It is recommended that researchers conduct a broader study of the salinity-tolerant physiology of this valuable medicinal plant to obtain more comprehensive information for afforestation programs.
Wetlands are one of the most important natural ecosystems in arid and semi-arid regions that their moisture content has decreased in recent years due to the adverse effects of climate changes and droughts. It is necessary to evaluate the... more
Wetlands are one of the most important natural ecosystems in arid and semi-arid regions that their moisture content has decreased in recent years due to the adverse effects of climate changes and droughts. It is necessary to evaluate the impact of such events on different ecosystems, especially these valuable ecosystems. In this study, the future drought status of Jazmourian wetland under elevated temperature was evaluated using the output of the IPCC Fifth Report Model. For this purpose, the standardized precipitationevapotranspiration index and reconnaissance drought index, which take into account the impact of rising temperatures due to future climate change on droughts, were used. The effect of increasing of temperature on drought risk was studied by using the return period of drought. Results showed that the standardized precipitation- evapotranspiration index was better able to show the effect of increasing of the evapotranspiration and temperature on drought than the reconnaissance drought index. Therefore, Standardized precipitation evapotranspiration was used to evaluate the future droughts under RCP scenarios. Based on the drought time series, by increasing temperatures, the future long-term droughts might be more intense and longer period than the historical period. Analysis of drought showed that drought risk would decrease on 3, 6 and 12-monthly time scales, respectively. Under the RCP2.6, RCP4.5 and RCP8.5 scenarios, the risk of drought will increase at all study time scales. In general, these results can be useful for assessing climate change and managing of water resources in arid regions.
Nepeta asterotricha Rech.f. is a medicine plant. The goal of this research is to investigate the effect of some environmental factors on amount of essential oil of Nepeta asterotricha Rech.f at 8 habitats in Yazd province to determine... more
Nepeta asterotricha Rech.f. is a medicine plant. The goal of this research is to investigate the effect of some environmental factors on amount of essential oil of Nepeta asterotricha Rech.f at 8 habitats in Yazd province to determine optimal environmental factors for rangeland management and reclamation. Soil samples were collected and measured phosphorus, nitrogen, and potassium and pH, electrical conductivity, and sand, silt, and clay (Hydrometric) at three replications from each habitat. Topographic factors including elevation, slop, and aspect were recorded in habitats. Plant samples in three replications in 8 habitat and essential oils were obtained by hydro distillation for 3 hours. Investigation on the correlation between essential oils and some ecological factors were done by using Redundancy Analysis v. 4. Comparison of means were done using Tukey tests (p≤ 0.05). Number of identified chemical compounds were 31 that 24 components had different between habitats. Results showed that the active ingredients in Nepeta asterotricha Rech.f including α-Thujene, α-Terpinene, p-Cymene, (Z) -β-Ocimene, γ-Terpinene, terpinen-4-ol, cis-Sabinene hydrate, α-Terpinolene, 4aβ, 7α, 7aα-nepetalactone and 4aα, 7α, 7aβnepetalactone had significant differences at 95% level in growing and flowering phases, and 8 habitats.The active substances of 1, 8-Cineole, cis-Sabinene hydrate, transCaryophyllene and Limonene had most of amount in the growing phase and the Rose furan epoxide, 4 aβ, 7α, 7aα-nepetalactone, α-Pinene, cis-Linalool oxide, α -Terpinolene in the flowering phase.Eelectrical conductivity, potassium, sand and elevation from sea level among environmental factors,had more effects in flowering phase. Scine, Thghiabad and Dehbala habitats had better situations of environmental factors and the essential oil are recommended to ude from the species of these habitats for reclamation of regions with similar environmental factors. Also these habitats were determined as the optimal habitats for this species in Yazd province.
Drought assessment and monitoring using traditional methods rely on rainfall data, which are limited in arid lands and often is very difficult to obtain near real time and costly. In contrast, remote sensing technology is a method for... more
Drought assessment and monitoring using traditional methods rely on rainfall data, which are limited in arid lands and often is very difficult to obtain near real time and costly. In contrast, remote sensing technology is a method for monitoring of large-scale drought. In this research, drought condition was analyzed using drought indices such as TVDI and NDVI from MODIS sensor data for the Yazd-Ardakan plain, Iran. First, relationship between the drought indices with climatic elements were detected. Coefficient of correlation between TVDI and SPI_6 and SPI_12 were 0.68 and 0.71, respectively. Correlation between NDVI and SPI_6 and SPI_12 were 0.49 and 0.51, respectively. Point correlation between TVDI and SPI_6 in 2004 (as a normal year), 2007 (dry) and 2012 (wet year), were 0.64, 0.78 and 0.67 and for the SPI_12 in the above-mentioned years were 0.65, 0.79 and 0.69, respectively. In other word, efficiency of the TVDI in 2007 is better than the other two years. Correlation of NDVI and SPI_6 in 2004, 2007 and 2012, were 0.41, 0.50 and 0.56, respectively. The correlation between NDVI and SPI_12 in 2004, 2007 and 2012, were 0.52, 0.57 and 0.59, respectively. TVDI which takes into account thermal and reflective bands, and soil moisture, is more accurate than the NDVI, which considers only amount of vegetation of the study area. Results showed that the relationship between vegetation and temperature is negative, while, the relationship between vegetation and precipitation is positive. Using of TDVI can compensate defects of the NDVI and used for identifying and monitoring drought.
Investigation of wind speed trend and analysis of its effective can be a suitable index to environmental variability related to air movement. Any increase or decrease in wind speed over time can impact on agriculture, soil erosion, wind... more
Investigation of wind speed trend and analysis of its effective can be a suitable index to environmental variability related to air movement. Any increase or decrease in wind speed over time can impact on agriculture, soil erosion, wind energy production, construction, mental health, and etc. In this study, wind speed trends and line slope by using MannKendall nonparametric test and Sen’s slope estimator were evaluated using wind speed data from 96 synoptic tations of Iran during their recorded period. Zoning of annual mean wind speed showed that four wind regions could be detected in Iran. Although the wind trend in Iran has no a certain temporal pattern, but in the northern half and mountain regions of the country, the trend is more pronounced. January and October with about 50%of the total station, and July and March with about 38% were observed maximum and minimum of the positive trends in the study area, respectively. Most of the area with negative trend is related to July by 13% and lowest is related to January, February, March and October by 6.25%. Generally, the positive trend is 43% and areas with negative trends is 9.3% of the total area of the country. Wind speed slope investigation shows that 75% of the country has positive slope and 25% of the country is with negative slope that have been expanded in all regions of the country. Most positive and negative slope is related to Gorgan and Chabahar Stations, respectively.
Understanding the effect of climate change on distribution of plant species is essential for sustainable management and conservation of rangelands, especially in arid and semi-arid ecosystems which are vulnerable to desertification,... more
Understanding the effect of climate change on distribution of plant species is essential for sustainable management and conservation of rangelands, especially in arid and semi-arid ecosystems which are vulnerable to desertification, because of their sensitivity and frangibility to climate change. Due to the complexity of natural systems and phenomenon of climate change, species distribution models are used to understand the impact of climate change on potential niche of species. In this study, five modeling algorithms including artificial neural network, generalized boosting method, classification tree analysis, multivariate adaptive regression splines and maximum entropy were used to predict current and future distribution of Artemisia sieberi Besser in Central Iran. First, the ensemble model as the average predicted probability of single models’ occurrence was created. Next, pessimistic (RCP 8.5) and optimistic (RCP 2.6) scenarios of CCSM4 and NorESM1-ME climate models for the years of 2050 and 2070 were evaluated to assess the trend in spatio-temporal variations of distribution. For this purpose, layers of environmental factors including six bioclimatic and two physiographic variables were used as inputs of species distribution models. Among the environmental variables, altitude, annual precipitation, isothermality, and slope had the most impact on the habitat suitability. Modeling evaluation indicated that the generalized boosting model had better predictions of climatic habitats than other models, and ensemble model than single models. Maximum probability of species presence was determined in plains and low slope areas at altitude of 1000-2000 m and annual precipitation of 100-200 mm. Analysis of the climate change scenarios showed that, the species habitat would be decreased in 2070 more than 2050, leading to the expansion of desert areas. The results can be used for planning to combat desertification in the habitat of Artemisia sieberi, as well as its restoration and rehabilitation in the vast regions of Iran.
This study was aimed to investigate the effects of seed biopriming with plant-growthpromoting bacteria (PGPB) on some characteristics of germination and growth of Astragalus ovinus Boiss under drought stress. This study was conducted as... more
This study was aimed to investigate the effects of seed biopriming with plant-growthpromoting bacteria (PGPB) on some characteristics of germination and growth of Astragalus ovinus Boiss under drought stress. This study was conducted as a factorial experiment in a completely randomized design, with three replications. Percentage, rate of germination, mean germination time, vigor, chlorophyll a, b, carotenoids, fresh and dry weight of radicle, shoot, embryonic leave, seedling and radicle length, shoot and seedling were determined. Plant-growth-promoting rizobacteria at five levels including Pseudomonas aeruginosa (Schroeter) Migula, Azospirillum lipoferm (Beijerinck) Tarrand, Bacillus cereus Frankland, Azotobacter chroococcum Beijerinck and the control treatment were considered as the first factor. The second factor was applying drought stress at four levels of 0.0, -0.2, -0.4 and -0.8 MPa. Among the four biopriming treatments tested, A. lipoferm and A. chroococcum were eliminated, because the seeds were failed to germinate and identified as agent pathogenic. Results indicate that the use of these two PGPB increase the characteristics of germination (percentage, rate of germination, mean germination time and vigor) and growth (fresh and dry weight, length and photosynthetic pigments) of A. ovinus. It can be concluded that these two bacteria increase effectively the growth of A. ovinus under different levels of drought stress. In general, these two bacteria play a role in reduction of the negative effects of drought stress on A. ovinus.
Measuring of subsidence is often challenging due to the gradual occurrence in large-scale, and advanced measuring techniques are required. The first foresighted consequence of this catastrophic phenomenon is irreversible loss of aquifer... more
Measuring of subsidence is often challenging due to the gradual occurrence in large-scale, and advanced measuring techniques are required. The first foresighted consequence of this catastrophic phenomenon is irreversible loss of aquifer reservoir. Subsidence is downward motion of the earth's surface with negligible horizontal vector component. Subsidence is occurring with different rates in many aquifers of the country constantly, because of excessive extraction of groundwater for years which causes lowering of the water table. Increasing the intensity of this phenomenon in recent years requires modern methods of measuring subsidence. InSAR technique can be strongly powerful that can extract vertical component in large extent, especially in areas with insufficient geodetic data. In this study, new Sentinel-1A imagery from 2014 to 2018 were used to examine the subsidence rate in the Kashmar and Khalil Abad plain. According to the high correlation between pair images, basic interferograms was calculated. Then, using SBAS method unnecessary phases were removed. Thereafter ,the displacement phase was calculated and converted to the vertical component. Maximum subsidence rate is observed near the southwest suburb of Kashmar city and western part of Khalilabad plain. Results indicate that the Kashmar and Khalilabad plain was encountered maximum of 17 cm downward movement annually. Due to uneven and heterogeneous subsidence, the area has susceptibility for formation of longitudinal cracks. Final map can be used to control and manage water resources and prevent natural hazards and desertification.
Lead accumulation in soil is influenced by various factors such as physico-chemical properties of soil, parent materials of rock, soil pollutant resources, organic and chemical fertilizers in agriculture and etc. So, the aim of this study... more
Lead accumulation in soil is influenced by various factors such as physico-chemical properties of soil, parent materials of rock, soil pollutant resources, organic and chemical fertilizers in agriculture and etc. So, the aim of this study is to evaluate the effect of soil physico-chemical properties on accumulation of lead in soil .The study area is located in 20 kilometers ambitious Aq- qala to Inche boroon road. Soil sampling was carried out in 5 blockswith distance of 3000 m. In each block six soil samples from 0-5 cm depth with a gap of 200 meters from each other were taken, totally 30 soil samples. After measuring the lead content, physical characteristics, texture and Bd and chemical, OM, SAR, CaCO3, EC and pH of soil samples were tested. Effects of soil properties on lead accumulation were analyzed by using linear and multiple regressions. Results showed that soil physical properties have no effect on the accumulation of lead. Among soil chemical properties, CaCO3 and EC had significant negative correlation and pH and OM had significant positive correlation with lead accumulation. Moreover, no significant relationship was observed between SAR and lead contents in the soil. Therefore, in the selected model based on the results of analysis of variance (by linear regression method), variables such as CaCO3, EC, pH and OM were selected as the most important factors that could express the lead concentration in the study area.
In arid and semi-arid ecosystems, woody and perennial plants are considered as a key factor in wind speed reduction and windblown sands sedimentation. The present study aims to evaluate the effect of different levels of soil additives on... more
In arid and semi-arid ecosystems, woody and perennial plants are considered as a key factor in wind speed reduction and windblown sands sedimentation. The present study aims to evaluate the effect of different levels of soil additives on morphological characteristics of Calligonum bungei Boiss. A greenhouse experiment was conducted in factorial plan in a randomized complete block design RCBD. In design of experiments, applied treatments were natural and municipal waste compost biochars as soil additives, each in four levels of 0, 1, 3 and 5%, mycorrhiza present or absent, and plant type. Results showed that treatment NO. 7 cause increased 34.62% in plant height, 42.38% in collar diameter, 554.02% canopy cover volume, 124.04% root length, 30.92% fresh weight of shoot, 36.23% fresh weight of root in mycorrhizal plants and treatment NO. 23 cause increased 39.24% in plant height, 35.98% collar diameter, 152.1% canopy cover volume, 17.74% root length, 68.53% fresh weight of shoot, and 20.75% fresh weight of root in nonmycorrhizal plant accordance with control treatment. Among the used treatment, those in the absence of mycorrhiza due to poor-quality of mycorrhiza and lack of interconnection between plant and mycorrhizal fungal networks had better growth than those of nonmycorrhizal plants. According to the results, treatment No. 7 due to low cost, greater accessibility, improve of soil fertility, and plant establishment were recommended in desert regions.
The present study investigated some habitat characteristics and ecological of Ochradenus ochradeni Abdallah in Abarkouh Bahman area for possibility of restoration function. Geomorphology, climatic and phenology and biometrical... more
The present study investigated some habitat characteristics and ecological of Ochradenus ochradeni Abdallah in Abarkouh Bahman area for possibility of restoration function. Geomorphology, climatic and phenology and biometrical characteristics of the population were investigated. Results showed the habitat had a middle to coarse soil texture with relatively high CaCo3 38.7± 26.07% and low CaSO4 2H2O, 0.19± 0.2% and pH equal of 7.1-8.5. The habitat of this species in some parts in bare pediment with low slope. Vegetation canopy of of the studied plant was low equal to 0.39%. Rainfall in all habitats was low and in Hossein Abad was 61.8 and in Bdaf was 47mm annually. The dry period of 10 months and monthly and annual distribution of rainfall was irregular. The highest number of accompany species equal to 52% belong to Chenopodiaceae. Growth season start at spring until mid-August and seeding stage is at summer until mid-August. Autumn and winter was equal to dormancy of this species. The highest germination percentage observed in KNO3 1% equal to 86.66% and KNO3 2% equal to 76.66% .Highest germination rate happened in KNO3 1% equal to 5.69 number per day. The lowest germination percentage and germination rate measured in moist chilling (in both 2 and 4 weekends) equal to 0.38%. Results showed this species grows from saline-sodium soils to non-saline-sodium soil. Therefore, it can be useful for rangeland restoration and saline soil improvement. This species are suitable for livestock feed and improving of vegetation through a scientific range management.
The purpose of research is to rezoning the climate zones of the north east of Iran- located between 30° 35' to 38° 41'N and 56° 19' to 61° 16'E- based on the analysis of changes in the aridity index, in combination with other climatic... more
The purpose of research is to rezoning the climate zones of the north east of Iran- located between 30° 35' to 38° 41'N and 56° 19' to 61° 16'E- based on the analysis of changes in the aridity index, in combination with other climatic parameters changes. Air temperature and precipitation parameters were provided in the scale of monthly average and annual over period time of 1990-2017. At first, the climate classification of the north east of Iran was revised by studying variations in precipitation, evapotranspiration and temperature and results were compared with the De Martonne and Köppen-Geiger climate classification. For analyzing the aridity status, trend of the above parameters in the form of UNEP index was tested using Mann-Kendall non-parametric method and Sen's slope estimator .Results indicated that applying of the aridity index, as a factor in improvement of the used pattern, caused the zoning of this method to be more precise than the previous methods. Therefore, the study area was classified into seven climatic groups, the zone Ac14 (Arid zone with cold winter and hot summer) with 39% and 9 stations, and Ec14 (Extremely-arid zone with cold winter and hot summer) with one station were the largest and smallest climate zones, respectively. Results of the Mann-Kendall test and trend line slope, for UNEP aridity index showed that the aridity and desertification intensity have increased in different parts of the area during 28 years.
Dust emissions by wind have significant implications for human health and ecosystems. The addition of effective materials in degraded soils is a suitable method for stabilizing soil accumulation, which can lead to reduced dust emission.... more
Dust emissions by wind have significant implications for human health and ecosystems. The addition of effective materials in degraded soils is a suitable method for stabilizing soil accumulation, which can lead to reduced dust emission. To investigate the effect of biochar and vegetation on soil improvement against wind erosion, a wind tunnel experiment was conducted. This study was carried out in order to investigate the effect of walnut wooden shell biochar (Juglans regia L.) walnut wooden shell powder and three patterns of vegetation including raw, random and zigzag, on the soil erosion of Shahrekord plain soil which is one of the dust source. Biochar and walnut wooden shell in 5% by weight in separate soils were tested in a 60 - day period in the simulated wind tunnel, along with three artificial vegetation patterns. The results showed that soil modification can indirectly control the wind erosion potential. The amount of soil erosion in day 60 of experiment was 1455 g/m2 for control sample, 1270 g/m2 for raw pattern, 840 g/m2 for random pattern and 397 g/m2 for zigzag pattern, that zigzag pattern caused more reduction in soil erosion in comparison with other patterns. Biochar and walnut wooden shell powder resulted in 46.82% and 24.14% in formation of flocculed soil, respectively, in comparison with control sample, which increased resistance to soil erosion. As a result, biochar and powder along with vegetation are able to stabilize the soil and increase soil stability and lead to a reduction in wind erosion.
The purpose of this study was to assess the effects of agricultural development on increasing the intensity of desertification in Dargaz plain in northern Khorasan Razavi province. The intensity of desertification caused by agricultural... more
The purpose of this study was to assess the effects of agricultural development on increasing the intensity of desertification in Dargaz plain in northern Khorasan Razavi province. The intensity of desertification caused by agricultural development, using important criteria that is mainly related to human activities, such as groundwater, irrigation and drainage, agriculture, soil, industrial-urban development, and socioeconomic criteria, in 20 years period from 1996 to 2016, were estimated using IMDPA model. Desertification intensity of Dargaz plain was classified into moderate and severe classes with frequency of 22% and 78%, respectively. Therfore, the irrigation and drainage criterion were the most important human factor in increasing of desertification intensity in this region. Then, soil criteria, agricultural development, urban-industrial development, socio-economic factors, and finally, quantitative and qualitative degradation of groundwater, respectively, had the most effective role in increasing the intensity of desertification in the agricultural land of Dargaz plain. Results showed that the increase of salinity in the eastern and northeastern parts of the region due to irrigation with salt water and the conversion of range and forest into agricultural and residential with an area of more than 7000 hectares over the past 10 years were the most important factors of increasing the intensity of desertification in this region. Therefore, to prevent extending of desertification, sustainable land management and preventing of land use change were suggested.
Total Dissolved Solids (TDS, mg/L) indicates the amount of soluble salts in water or in a solution, and usually calculates by measuring the electrical conductivity (ECdw, μS/cm) and then multiplied by 0.64. This is a general conversion... more
Total Dissolved Solids (TDS, mg/L) indicates the amount of soluble salts in water or in a solution, and usually calculates by measuring the electrical conductivity (ECdw, μS/cm) and then multiplied by 0.64. This is a general conversion factor (CF) and its amount varies depending on the water-soluble components. In fact, TDS meters determine TDSvalueby measuring of the EC solution and default or user-selected CF. Hence, the precise method is to calculate this coefficient according to the solute type. In this research, to determine precisely the amount of soluble solids along with suspended dust in MDCO sediments traps installed in the north of the Yazd-Ardakan plain. To obtain the TDS calculation coefficient from ECdw resulting from leaching of small amounts of dust, three methods including of an experimental coefficient of 0.64, physical vapor deposition weighing and measuring the concentration of ions affecting chemical salinity were compared. Comparison of mean of the CFs obtained from the three methods showed that the TDS value of the method of coefficient of 0.64 for determination of TDS from ECdw, was significantly lower than the other two methods. Hence, applying of this method, leads to a low level of solute content with dust in the study area. The average of the TDS conversion factor obtained by the physical and chemical methods without significant differences were 1.03 and 0.90 respectively, compared to 0.64 in the experimental method, that makes it possible to calculate more precisely the TDS from the measured ECdw data that derived from leached dust, and it can be used to adjust the TDS conversion factor in EC and TDS simultaneous measurement devices.
In water systems, precipitation is considered as input and evaporation as the output of the system. Water availability can be estemated from the relationship between these two factors. Therefore, evapotranspiration is the most important... more
In water systems, precipitation is considered as input and evaporation as the output of the system. Water availability can be estemated from the relationship between these two factors. Therefore, evapotranspiration is the most important factor after precipitation in hydrological cycle. Evapotranspiration is influenced by climatic parameters such as temperature, wind, humidity and sunshine hours. In this research, changes in PET and effective climatic parameters, influencing on PET changes including temperature, wind, humidity, and solar radiation were investigated. For this purpose, PET in 14 weather stations of Yazd province were calculated using the FAO-Penman-Monteith method. Due to the lack of sunshine hours data in some stations, regeneration of the incomplete data was done by using regression method. Due to the lack of wind speed data at some stations, their reconstruction by using data from other stations was done by applying three methods of Inverse Distance Weighted, Kriging and Cokriging. After calculating potential evapotranspiration, PET data were zoned and their monthly and annual trends tested by Mann-Kendall test. Despite occurrence of climate change and increasing of temperature in 13 stations out of the 14 stations, it is expected an increase in potential evapotranspiration in past few decades, while, there is a decreasing trend in PET. Investigating on the effective parameters in potential evapotranspiration showed that wind speed has declined in the last few decades, and despite of an increase in temperature, potential evapotranspiration rate reduces in 64.3% of the stations. General trend of evapotranspiration was -0.86 in this period, which indicates a decrease in evapotranspiration in the Yazd province.
Understanding of distribution of plants and analyzing their spatial pattern reveal the interactions of plants and environment. Nebka as an indicator henomenon of plantsediment interaction, plays an important role in protecting of... more
Understanding of distribution of plants and analyzing their spatial pattern reveal the interactions of plants and environment. Nebka as an indicator henomenon of plantsediment interaction, plays an important role in protecting of vegetation and sand stabilization. The aim of the present study was to evaluate the interaction of Nebka and plant based on a field study, measuring the morphometric parameters, and precise point positioning. Therefore, 322 Nebkas and 119 plants were determined in the northern region of Aq-Qala, Golestan province. In order to investigate and determine the spatial pattern and interactions of Nebkas and plants, and impact of soil parameters on their distribution pattern, univariate and bivariate functions including g and mark correlation functions were used. The pair correlation function showed that spatial pattern of plant at distance of less than 23 m was irregular. This means there is no competition between plants at distance of less than 23 m. Furthermore spatial pattern of Nebka was irregular at distance of less than 23 m. Bivariate g function at distances less than 50 m indicated positive correlation between plant and Nebka. Therefore, all plants and Nebkas have a positive impact on formation and distribution of each other. Results of the MCF function with 95% probability showed that soil properties such as EC, pH, OM, SAR, and skewness of Nebka sediments influence the Nebka’s pattern in the study area.
Surface albedo is one of the key controlling geophysical parameters in surface energy budget research and environmental and climate studies. As an efficient tool for monitoring earth surfaces, remote sensing is widely used for estimating... more
Surface albedo is one of the key controlling geophysical parameters in surface energy budget research and environmental and climate studies. As an efficient tool for monitoring earth surfaces, remote sensing is widely used for estimating albedo over recent decades and various algorithms of satellite data have been developed to estimate albedo. Up to now, albedo has been estimated using different types of sensors. This study presents procedures for computing of albedo using OLI sensor Landsat 8 data in different geomorphology facies, arable soil and asphalt in the Yazd- Ardakan Plain. In this way, required data from each nine images metadata of Landsat 8 were extracted for summer and autumn, 2017 and then albedo was calculated using meteorological data. Results showed that there is a difference between values of albedo in different geomorphology facies. Surface albedo average of clay land, pavement, sand dune, bare land, sand sheet, arable land and asphalt are 0.30, 0.22, 0.24, 0.26, 0.24, 0.23 and 0.24, respectively. The highest calculated albedo is related to clay land, while the lowest is observed in desert pavement facies.
Wind erosion is one of the most important natural processes in arid and semi-arid regions. In recent years, due to lake drying, dust producing has been increased from lakes and wetlands surfaces. Maharloo Lake, as one of the most... more
Wind erosion is one of the most important natural processes in arid and semi-arid regions. In recent years, due to lake drying, dust producing has been increased from lakes and wetlands surfaces. Maharloo Lake, as one of the most important saline lakes of Iran, dried up in recent years. This research aims to study the susceptibility of Maharloo Lake sediments to wind erosion and determining of direction of the Lake surface dust movement. At first step, texture of the sampled sediments were determined. Next, direction of the dominant and erosive winds were determined by drawing wind and storm rose graphes and concentration of dust was calculated over a period. Results of sediment granulometry and hygrometry showed that more than 60% of the Maharloo Lake sediments were silt. Results of wind and storm roses showed that the direction of dominant wind is west and northwest; while the direction of erosive wind is western. According to the results of dust concentrations from two TSP and PM 2.5 samplers around the lake, it is derived that the amount of dust collected from the lake’s sediments is higher than normal. Also, based on the dominant wind direction, created dust would affect mostly villages around the lake and also, Sarvestan Township. Therefore, in regard to the percentage of particles frequency containing Maharloo Lake’s sediments and their high sensitivity to wind erosion, this challenge described in advanced will soon become apparent to other cities located in Fars province and even to other adjucent provinces.
Identification of suitable sites for solar power plant establishment in arid regions is very important for using high potential solar energy. This study aimed to identify more important factors influencing site selection for solar power... more
Identification of suitable sites for solar power plant establishment in arid regions is very important for using high potential solar energy. This study aimed to identify more important factors influencing site selection for solar power plant establishment and to determine highly suitable sites to establish solar power plants in Sistan region. Influencing factors on site selection were selected based on experts’ opinion using Analytic Hierarchy Process (AHP) with regard to climatic, geographic, socio-economic and environmental variables. Paired comparison of criteria and sub-criteria was performed using fuzzy analytic hierarchy process to determine the weight of each criteria. After preparing of the layers of criteria using GIS teqhniques, weights of criteria were multiplied in theircorresponding layer. Finally, site suitability map for solar power plant establishment in Sistan region was prepared at five classes through overlaying of layers. Based on results, 4.8 percent of Sistan region, which is located in the southern part of Zahak and Hamoun cities and eastern parts of Nimrouz city, has an excellent suitability for solar power plants establishment. In addition, 36.6% of the study area has a good suitability, 0.5% has a moderate suitability and 18%, which is located in Bandan and Sefidabeh areas, has a poor suitability for solar power plants. Furthermore, sunny hours, temperature and elevation parameters because of having more weight, were identified as the most important criteria. Results indicated that about 45% of Sistan region has high suitability for solar power plants establishment. Therefore, the investment risk of the solar power plants in Sistan region is low. Maximum utilization of solar energy can provide a favorable condition for economic development and increasing the survival of people in Sistan region.
One of the most common and destructive phenomena in arid and desert regions is dust which can have negative effects on the environment. Eastern half of the country has always been exposed to this phenomenon due to its geographical... more
One of the most common and destructive phenomena in arid and desert regions is dust which can have negative effects on the environment. Eastern half of the country has always been exposed to this phenomenon due to its geographical location and even to 120-day winds. The present study aims analyze and Clustering dust storms in eastern of Iran. For this purpose, hourly data of dusty days, phenomena code, horizontal visibility, wind direction, speed and current weather of 17 weather stations in eastern Iran during period of 1986 to 2016 were used. Dust storm codes were used for statistical analysis. Then, trend type and value were detected using Mann-Kendall (MK) and Sen's estimator tests Using WRPLOT View, dust rose of the area was drawn. Results showed that the frequency of dust storms in July was the highest and the lowest occured in December. The intensity and distribution of dust in the south-east of the region was more than other regions. Results of MK test suggested a significant increase in southeast, central and northwest stations, while most stations in north part of the region showed a significant decrease. Dust rose results also probes the direction and speed of winds causing dusty storm were different in east and west of the region. The direction of wind causing dusty storm in the eastern half is between 70° to 300°, while in western part of the region, wind blows between 260° to 280° geographic coordinate system at speed of more than 11 m/s.
Net primary production (NPP) is one of the most important factors in ecosystem's function, which is affected by biological and climatic factors. The main objective of the current research was to investigate the potential of the CASA... more
Net primary production (NPP) is one of the most important factors in ecosystem's function, which is affected by biological and climatic factors. The main objective of the current research was to investigate the potential of the CASA (carnegie-ames-stanford approach) model in determining the spatial and temporal distribution of NPP in rangland types of arid regions of Isfahan province using MODIS and Landsat. For this purpose, satellite and climatic data such as rainfall, temperature, monthly and sunny hours, were used. The NPP was modeled on two Landsat and MODIS scales and correlations between field measurements and CASA model were investigated based on rangeland conditions and vegetation types. Results showed that the highest plant production in the region was during the March-May months. Crrelation between CASA model with field data occurred in MODIS was higher than Landsat data. Based on the relations, the values of NPP and LUE (light use efficiency) were investigated in the region. The NPP spatial distribution and LUE values indicated that the amount of annual production and photosynthesis efficiency were decreased in degraded rangelands (poor and very poor conditions) compared to fair rangeland condition. The highest and lowest amount of NPP observed in Artemisia sieberi – Zygophyllum Spp (9.35 g C/m2y-1) and Annual grasses - Annual forbs (0.2 g C/m2y-1), respectively. The amount of NPP and LUE in shrublands and annual plant types were higher than bushlands.Results of this research probes the importance of biological classification, climate and scale of study in NPP modeling. Moreover, the stratification of rangelands based on life forms and range conditions has principal role in accuracy of the NPP estimation.
Environmental pollution as a desertification consequences, is one of the most important challenges in human societies. Nitrate and phosphate are two important pollutants, which are created from chemical fertilizer and cause water... more
Environmental pollution as a desertification consequences, is one of the most important challenges in human societies. Nitrate and phosphate are two important pollutants, which are created from chemical fertilizer and cause water resources pollution. There are different techniques for remediation, but due to the sensitive and fragile propertise of deserts ecosystem, phytoremediation process is a natural remedy utilized by agricultural system. This study aims to assess the phytoremediation potential of Ailanthus altissima Mill. and Fraxinus excelsior L. for removal of Nitrate and phosphate in water by factorial experiment in randomized complete block design. Firstly, a total number of 96 trees from the two species were planted in Isfahan University of Technology. In the current study, three levels of phosphate (5-10-50 mg/L) and nitrate (5-10-50 mg/L) for each of the species were and a blank sample with three were considered replicates. Nitrate and phosphate pollutants were investigated in three densities of 5-10-50 mg/L in 3 replications. Afterwards, the level of nitrate and phosphate removal were measured. Results show that nitrate removal levels in 5, 10 and 50 mg/L concentrations in first week by A. altissima are 74.53, 75.23, and 79.95% and by F. excelsior are 79.04, 80.65, and 83.97%, respectively. Likewise, phosphate removal in 5, 10 and 50 mg/L concentrations by A. altissima are 74.10, 77.18, and 82.81% and by F. excelsior are 74.16, 79.87, and 83.56%, respectively. There is a significant difference between A. altissima and F. excelsior in removing nitrate and phosphate.
Salt domes are one of the most interesting geomorphologic landforms that have great potential in attracting tourists and developing the geotourism industry. Due to the existence of various salty geomorphosites in Semnan, there are not... more
Salt domes are one of the most interesting geomorphologic landforms that have great potential in attracting tourists and developing the geotourism industry. Due to the existence of various salty geomorphosites in Semnan, there are not systematic researches for estimating these geomorphosites for developing tourism and creating its infrastructures. Therefore, it is necessary to estimating the capability of salty diapirism landforms in developing tourism in the study region. In the present study, we try to estimate the data of field observation and questionnaire information about geamorphosite value of salty domes in the south of Semnan by using Reynard and Pereira methods. The present research is quantitative in terms of research paradigm, field, library and questionnaire in terms of collecting data, and in terms of purpose is applied, which is based on descriptive-analytical method. First, the results of literature were studied, field measurements and interpreting the satellite images have presented in the form of recognition sheet, then have given scores to each criteria and sub-criteria in Reynard and Pereira method, according to experts opinion and field observations. The results indicated that in the Reynard method, the scientific value (0.785) and combination value (0.547) and in the Pereira method, Geomorphological value (6.74) and Managerial value (4.66) have obtained the highest and lowest scores, respectively. The high scientific and geomorphological values in geomorphosite is due to the aesthetic values and educational capability of geomorphologic processes, and then the virginal of the landforms in the area due to the unfamiliar of these geomorphosites to tourists and the lack of attention of the officials to these tourist attractions. In contrast, low values of combination and management, indicates poor management and lack of support equipment and services in the region. In general, geomorphosite obtained a good final score based on two methods, which indicates the high capability of geomorphosite in the attraction of tourism. The results of present research can be used by decision makers to develop the salt geotourism in the province.
This study investigated the vegetative and physiological characteristics of Hammada salicornica Syn.: Haloxylon salicornicum under sand burial. Experiment conducted in completely randomised design with five replicates. One year-old... more
This study investigated the vegetative and physiological characteristics of Hammada salicornica Syn.: Haloxylon salicornicum under sand burial. Experiment conducted in completely randomised design with five replicates. One year-old seedlings of Hammada salicornica in the same size assigned to one of the following five burial treatments, control, buried to 33% of plant height, buried to 50% of plant height, buried to 75% of plant height and buried to complete plant height. After 6 months watering under glasshouse conditions, some of vegetative and physiological characteristics of Hammada salicornica were measured. Results showed the highest amounts of leave proline equal to 20.8 mg/gfw observed in 33% burial treatment. Root proline in all burial treatments were significantly more than two times compared to control. The root proline in 33% burial traetment was equal to 22.72 mg/gfw that was two times more than control. The amount of oxine significantly increased in 33% and 50% burial treatments compared to control. The amount of oxine in 33% burial treatment was equal to 0.64 mg/gfw that was two times more compared to the control. The amounts of stem sugar were deacreased in all burial treatment while heighest amounts of root sugar were measured in 33% burial treatment. Stem and root sodium, 22 meq/l, significantly increased in 33% and 50% compared to control and 75% burial treatment. The amount of root and stem potassium content in 75% of burial treatment was significantly lower than other burial treatment. The amounts of stem phosphorus, 0.73 meq/L, and root phosphorous, 1.9 meq/L, observed in 33 % of burial treatment. The amounts of root phosphorus significantly increased in all burial treatment compared to the control. Moreover, the stem hieght in 75% burial treatment, 40 cm, were more than two times compared to the control. The highest amount of stem and root dry and wet weight in 33 % of burial treatment was significantly more than other burial treatments. It is concluded that Hammada salicornica tolerate not only 33% of burial treatment but also the burial stimulates the growth.
Declining condition of water resources cannot be shown by single-variable drought indices because of changes in precipitation and temperature due to climate change. Accordingly, multivariate drought indices are considered such as the... more
Declining condition of water resources cannot be shown by single-variable drought indices because of changes in precipitation and temperature due to climate change. Accordingly, multivariate drought indices are considered such as the Standardized Precipitation Evapotranspiration Index (SPEI). In order to study the trend of changes in the severity of meteorological drought in the geographical zone of Iran, the SPEI global network data was used over a 30-year statistical period, and trend detection test and Sen's slope estimator were performed on their seasonal series. Then, their results were mapped in the GIS and the results showed that the highest drought trend is in the winter between seasons, and more than 94 percent of the country's area shows a declining slope in the drought index time series. The trend of this slope in the west and north-east of the country is statistically significant. Also, the eastern half of the country shows a drought trend in the summer, but a better situation prevailing in Iran in spring and autumn, and a small percentage of the country's area indicates a significant drought trend. So that in the spring and autumn, the slope of the trend line in 85 and 91 percent of the country is less than and equal to 2 percent, respectively. Generally speaking, the result of the Standardized Precipitation-Evapotranspiration Index showed that climatic changes are occurred in Iran and the country is going towards more dry periods in future years.
Astragalus squarrosus is a species of shrub without spine and palatable. This plant distributes in sandy dunes of arid and hyper arid regions in central, south-eastern and north-eastern desert of Iran. In this study the effect of rain... more
Astragalus squarrosus is a species of shrub without spine and palatable. This plant distributes in sandy dunes of arid and hyper arid regions in central, south-eastern and north-eastern desert of Iran. In this study the effect of rain harvesting treatments including furrow, pitting and crescent pond and planting season on initial establishment of A. squarrosus in Kalmand Bahadoran was evaluated. This region in terms of soil type, condition of rainfall and temperature is similar of the main habitat of this species. The seeds were planted at two season late fall as autumn sowing and late winter as spring sowing season. Also, the seeds were scratch according to germination studies in the lab. The scratched seeds were compared in split plot design with main treatment of planting season in the autumn of 2013 and 2014 and winter of 2013 and 2014. Subsequent treatments of pitting, furrow, crescent pond in three blocks were compared. In the spring, the number of established plants in each plot was counted and analyzed. Based on the results, fall planting been more successful than spring planting. Also, furrow treatment with 11.5% seed establishment had better results in seed establishment than other treatments. Also, the results of season and treatment interaction showed that 27% of seeds were planted in furrow during autumn 2013. But seeds in any of the treatments were not grown in winter 2014. Generally, low seed establishment suggests that rain storage combined with seeding in areas with average rainfall less than 100 mm faces with a high risk. In these areas, methods of potted seedlings combined with rain harvesting should be examined.
Present study was conducted to find out the effect of arbuscular mycorrhizal fungi Glomus intraradices and the plant growth promotion rhizobacterium Pseudomonas putida inoculant on the concentration of macro and micro elements and... more
Present study was conducted to find out the effect of arbuscular mycorrhizal fungi Glomus intraradices and the plant growth promotion rhizobacterium Pseudomonas putida inoculant on the concentration of macro and micro elements and seedling quality indices of Calotropis procera seedlings in a completely randomized design with three replications. The results of one way ANOVA showed that measured parameters of nutrients and seedlings quality index have been significantly influenced by the inoculation fungi and bacteria. The Duncan’s comparison of mycorrhizal inoculum than control in total root nitrogen concentration was 26%, iron concentration in leaves and root were 70% and 52% as well as potassium and zinc concentration in the leaf as of 5% and 45%, respectively that compared to the control has increased. Mean comparison of Rhizobacterial inoculation with control showed that total nitrogen, iron and manganese concentrations in the leaf were 57%, 450% and 225% respectively, and iron and zinc concentrations in the root increased 58% and 84%, respectively. According to thehe mean comparison of Duncan’s, mycorrhizal treatment with Rhizobacterial had increase in total nitrogen, potassium, iron and zinc concentrations in leaf by 51%, 48%, 450% and 31%. Nitrogen and potassium in the root were observed at 48% and 300%, respectively. Comparing seedlings quality indices, inoculated seedlings of the Rhizobacteria with the index of 0.85 were highest rate, which was 66% higher than the control. The results of this study indicated that inoculation of mycorrhizal and Rhizobacterial has increased in nutrient content and quality of seedlings. Despite the slight differences between inoculations, it is recommended to use both types of mycorrhizal and Rhizobacterial inoculum in order to replace the fertilization in the culture media in nursery.
In the present study, four supervised classification algorithms including Maximum Likelihood, Mahalanobis Distance, Minimum Distance and Neural Network with and without TIR1 were used to mapping land use of southern Khorasan province.... more
In the present study, four supervised classification algorithms including Maximum Likelihood, Mahalanobis Distance, Minimum Distance and Neural Network with and without TIR1 were used to mapping land use of southern Khorasan province. Based on the results, the highest of overall accuracy and Kappa coefficient were calculated for the Maximum Likelihood algorithm with and without of TIR1. Using of TIR1 increased classification accuracy by Maximum Likelihood and Mahalanobis Distance algorithms; but using of TIR1 decreased classification accuracy by Minimum Distance and Neural Network algorithms, remarkably. Using of thermal data along with other spectral bands caused facilitation of discriminating classes with similar spectral characteristics. According to the land use map, bare land covered about 60% area of southern Khorasan province, generally more than 90% of the area of the province is involved by sparse land or weak vegetation cover which is prone to wind erosion.
Identification of the origin of sand dunes and determining their sensitivity are very important for combating wind erosion. The main aim of this research is investigating sediment characteristics and classification of sand dunes created... more
Identification of the origin of sand dunes and determining their sensitivity are very important for combating wind erosion. The main aim of this research is investigating sediment characteristics and classification of sand dunes created at the western margin of Lake Urmia. At the first, geomorphological unit map was prepared, then 21 and 12 surface samples were selected from detachment wind sediments areas and sand dunes, respectively. The results of morphometry showed that frequencies of particle size are 125-500 micron indicated the short distance transport of particles and close to the site of the deposit. Also, sorting index is poor in detachment wind sediments areas and moderate to good in sand dunes. The index of particle skewness is very fine, fine, symmetrical, coarse, and very coarse and the kurtosis index is classified in categories of Platykurtic, Mesokurtic, Leptokurtic and Very Platykurtic. The results of morphoscopic analysis of quartz beads in 250-micron mesh sieve showed that around 53%, 14.4% and 40% segments of the sediment in sand dune were corona, brilliant carried by water and opaque carried by wind, respectively. Based on Besler classification, sand dunes located in saline and extremely saline classes showed that local winds carrying fine salt particles from the Urmia Lake toward sand dunes.
Climatic variables are considered as one of the most important factors affecting the spatialtemporal dynamic of vegetation. Nowadays, satellite images are widely used for monitoring the effect of climatic variables fluctuations on... more
Climatic variables are considered as one of the most important factors affecting the spatialtemporal dynamic of vegetation. Nowadays, satellite images are widely used for monitoring the effect of climatic variables fluctuations on vegetation changes. The purpose of this study is to investigate the relationship between two climatic variables of precipitation and temperature with vegetation dynamic in one of the world’s dry plains i.e. Sistan plain in eastern Iran by using satellite data. In the present study, the data generated in NDVI related to MODIS sensor of Terra satellite for 3 months of April, May, and June over 2000 to 2014, data of temperature and monthly precipitation (October- September) in Zabol meteorological station were used for the same time period of 2000-2014. Pearson product moment correlation was used to study the relationship between climatic variables with NDVI. The results showed no correlation between MODIS NDVI of April, May, and June with the average temperature of previous months in terms of monthly scale. In case of precipitation, it was observed that the precipitation of May with MODIS NDVI of May 0.603 and June 0.542 had a normal positive correlation. But due to the very low amount of precipitation and high evaporation in this month, this correlation cannot be trusted a lot. Thus, by recognizing no correlation between climatic variables and vegetation dynamic in Sistan plain, the correlation between the average annual discharges of Hirmand river was considered as the only river in this plain with MODIS NDVI of April, May, and June. The results of correlation showed a strong positive correlation of 0.75 between the average annual discharges of Hirmand river and MODIS NDVI of April. Thus, it is obvious that the critical vein of Sistan plain is Hirmand river and the life in this land and its vegetation dynamic depends not only on temperature fluctuations and precipitation but also on the water of this life-giving river.
In the present study the most effective climatological parameters for prediction of evapotranspiration using feature selection algorithm in Darab city located in southwest of Fars province was selected. In the first stage, the values of... more
In the present study the most effective climatological parameters for prediction of evapotranspiration using feature selection algorithm in Darab city located in southwest of Fars province was selected. In the first stage, the values of evapotranspiration were calculated based on FAO Penman-Montith method, then using feature selection method, the most effective parameters were selected among all effective parameters to evapotranspiration prediction based on FAO Penman-Montith method. Using Best First, Greedy Stepwise and Ranker as the most famous methods of feature selection the most effective parameters from 120 data were selected. Also in order to investigate of the error of each method to choose the best method Naïve Bayes, J48 and LMT was used. Using minimum, maximum and average temperatures, relative humidity, sunshine and maximum sunshine hours, wind speed, clear sky solar radiation (Rso), (75% of solar radiation in the upper atmosphere), the evapotranspiration was predicted. The results show that Ranker method with Relifef- Attribute-Eval in Naïve Bayes, J48 and LMT method had the lowest error. So maximum sunshine hours, maximum and average temperatures were found to be the most effective parameters for prediction of evapotranspiration. Using feature selection algorithm can be useful to predict of evapotranspiration in regions with limited data and save time and money.
Aerosols play an important role in the climate system of the atmosphere. These atmospheric particles are directly affected by changing radiation exposure by diffusing and absorbing different wavelengths and indirectly by changing the... more
Aerosols play an important role in the climate system of the atmosphere. These atmospheric particles are directly affected by changing radiation exposure by diffusing and absorbing different wavelengths and indirectly by changing the optical properties and the durability of the clouds, and the optical properties of the aerosols, such as aerosols optical depth (AOD), are critical in understanding the effects of atmospheric aerosols on climate change and biogeochemical cycles. Therefore, in this research, the ability of radiation transmission model and MODIS images was evaluated to estimate the aeroeses optical depth in Persian Gulf. MATLAB was used for images processing of the images with resolution of 500 m at 5×5 networks. The evaluation of aerosoles optical depth data was performed by using AERONET stations with Pearson correlation, RMSE and RMSD indices. First results of the algorithm implementation showed the ability of model to simulate the aerosols optical depth. Modeling results showed that the algorithm is correct and according to spectral reflectance data for effective radius of the LUT tables, values simulated for aerosols optical depth. The results of evaluation showed that optical depth values obtained from the images has significantly correlation with the measured optical depth in AERONET stations. So that, amount of correlation calculated form 29 June 2013, 14 July 2014 and 6 October 2015 in the band of 1.243 is 0.96, 0.94 and 0.98 respectively, and for the band of 1.643 is 0.99, 0.98 and 0.98, respectively which shows a good trend between the measured data, RMSE and RMSD indices were calculated in these days less than 0.15 and less than 0.06, respectively. It can be concluded that simulations accuracy is appropriate in these bands.
Shifting aeolian dunes damage to infrastructure in Sistan plain. Accordingly, distribution, morphology and fixed and unfixed status of sand dunes in erosive corridors were surveyed by using satellite images and field investigation. Mean... more
Shifting aeolian dunes damage to infrastructure in Sistan plain. Accordingly, distribution, morphology and fixed and unfixed status of sand dunes in erosive corridors were surveyed by using satellite images and field investigation. Mean wind velocity, average seasonal and annual sand drift potential, resultant drift direction, resultant drift potential and unidirectional index (RDP/DP) were calculated using hourly wind speed and direction data in six meteorological stations around Sistan plain. In addition, temporal and spatial variation of wind energy were mapped using Kriging geostatistical method. The results show that activity of sand dunes matched wind of 120 days which lifted sediment from the dry beds of Hamoun Lake into 4 erosive corridors based on topography which forms Registan sand seas in the southwest Afghanistan. The types of dunes are Barchans, transvers and sheet which is formed by unidirectional wind. The DP decreased from northwest to southeast of region and the value of drift potential in Zabol station was calculated 2516 vector unit that it is one of the highest values in inland deserts of the world.
In this study, land degradation in Isfahan province in the period of 2001 - 2014 was monitored using trends analysis in terms of two indices of NDVI and RUE. To do this, MODIS satellite images with MOD13A2 code was used to investigate the... more
In this study, land degradation in Isfahan province in the period of 2001 - 2014 was monitored using trends analysis in terms of two indices of NDVI and RUE. To do this, MODIS satellite images with MOD13A2 code was used to investigate the vegetation degradation and for calculating the RUE, which is obtained from the NPP to rainfall ratio. The MODIS images with MOD17A3 code was used to calculate NPP and Kriging method was applied for obtaining rainfall map. The results showed that NDVI had an increasing trend while RUE had a decreasing trend based on annual rainfall. Evaluation of land degradation in the time period (2001-2014) and comparing the regression relationship between the two indices of NDVI and RUE in different land uses (agriculture, rangeland, forest and desert) of the study area showed that RUE trend was increasing in agriculture, rangeland and forest land uses, so that in 2001, the value of this index in the mentioned land uses was 0.2, 0.142 and 0.149, respectively and 0.61, 0.099 and 0.106 in 2014. In the desert regions, the trend of the two indices was decreasing, so that the value of RUE in 2001 and 2010 was decreased by the factor of 0.097 and 0.2131 g c m2 per year, respectively. Based on the results, it can be seen that the ecosystem of the study area is degrading.
This study investigated the effects of different concentrations of salinity stress on some morphological and physiological characteristics of Ammodendron persicum using a randomized complete design with four replicates. The salinity... more
This study investigated the effects of different concentrations of salinity stress on some morphological and physiological characteristics of Ammodendron persicum using a randomized complete design with four replicates. The salinity factors were control, salinity concentrations of 2. 4. 8 and 12 ds/m and the results showed that salinity significantly affected on all morphological characteristics of the plant. The salinity decreased stem diameter, the number of leaves, stem height, wet and dry weight of aerial parts and increased wet and dry weight of root. The results also showed that salinity increased the amounts of proline in which the highest amount of proline measured in salinity of 12 ds/m and was equal to 0.046 mg/g and the lowest amount measured in control and was equal to 0.022 mg/g. The highest amount of soluble sugar measured in salinity of 12 ds/m and was equal to 0.75 mg/g while the lowest amount measured in control which was equal to 0.63 mg/g. Increasing salinity also increased the amounts of chlorophyll a, b and total chlorophyll. Increasing salinity decreased percentage of Nitrogen and the highest amounts of N measured in control (equal to 2.13%) and the lowest found in 12 ds/m (equal to 1.57). Increasing salinity decreased also the amounts of K+, P+, Ca++, Mg++, and K+/Na+ and increased the amounts of Na+. It is concluded that Ammodendron persicum is not resistant to salinity and would not have suitable growth in soil with salinity more than 2 ds/m.
Drought with its effects on the performance of agricultural productions, water resources and vegetation cover accelerates the expansion of desertification. One of the methods for drought study and its devastating effects is monitoring and... more
Drought with its effects on the performance of agricultural productions, water resources and vegetation cover accelerates the expansion of desertification. One of the methods for drought study and its devastating effects is monitoring and mapping of drought using meteorological indices and remote sensing techniques. To determine the impacts of drought on vegetation cover changes, the intensity of the drought was determined using the annual drought indices (i.e. the annual SPI and RDI). For drought indices mapping, five interpolation methods were used and compared. Then, the annual and seasonal average of NDVI was calculated using the MODIS 16-day NDVI time series from 2000 to 2014. The relationship between the drought indices (SPI and RDI) and the NDVI in different vegetation coverages was evaluated in Yazd province. According to the zoning of drought indices, Yazd province has been in a state of severe drought between 1999-2000 and 2007-2008. Evaluation of correlation results between different vegetation coverages type in Yazd province with drought indices showed that the semi-dense forests, woodlands, shrub-land, and pasture were severely affected by drought while the planting forests, agricultural areas, and gardens were less affected. Based on the results of coefficient of determination (R2) maps, the highest correlation between the average of NDVI in the spring and the annual drought index (SPI) was founded in the semi-dense forests, woodlands, shrub-land, and pastures grade 2 and 3 with the R2 of 57, 50, 44 and 41 percent, respectively. Likewise, in the summer, the semi-dense forests, pastures grade 1, 2, and 3, woodlands and shrubbery zones, had the R2 of 62, 51, 41, 35 and 44 percent, respectively.
Due to some factors such as limitation of water resources, increasing demands in all aspects and also the impact of climate changes, the optimal management of water resources and their efficient use is an essential task. To achieve this... more
Due to some factors such as limitation of water resources, increasing demands in all aspects and also the impact of climate changes, the optimal management of water resources and their efficient use is an essential task. To achieve this effective management, appropriate water resources planning can be utilized. One of the basic parameters of the water management is the accurate calculation of water balance components. Present study was conducted to determine the effects of Haloxylon aphyllum artificial forest on groundwater extraction from Yazd-Ardakan aquifer. To achieve this, numbers of Haloxylon aphyllum shrubs were counted using JMicrovision software on the preprocessed Google Earth images. Then considering annual water needs of Haloxylon aphyllum- obtained from lysimetric data of previousstudies- and number of Haloxylon aphyllum counted from Google Earth images, water extraction of planted forest was calculated. In next step, using GMS 8.3 and Modflow model, the aquifer balance and effective storage coefficient were obtained for calculating groundwater extraction of Haloxylon aphyllum in Yazd-Ardakan aquifer. The results showed that the 4423640 Haloxylon aphyllum existed in the Yazd-Ardakan plain and there is 56 million cubic meters of shortage in reservoir capacity. The amounts of groundwater extraction by Haloxylon aphyllum forest was estimated about 1.614 million cubic meters per year. The positive role of reforestation in relation to the dust storm damage reduction rounded and included the use of water should not be ignored. The results of the research are applicable for water resources and water use management of plantation forests.
Desertification means land degradation in arid, semi-arid and dry sub-humid regions as a result of various factors, including climatic variations and human activities. In this research, the study area with an area of 136 thousand hectares... more
Desertification means land degradation in arid, semi-arid and dry sub-humid regions as a result of various factors, including climatic variations and human activities. In this research, the study area with an area of 136 thousand hectares located 20 kilometers far away from east Isfahan was selected. Due to the proximity of this area to Isfahan city and the impact that desertification phenomenon on the city, studying the desertification in this region is of great importance. To assess the current status of desertification, the multi criteria Analysis and MEDALUS model was used. For this purpose, in the first step and based on the local situation, six qualitative criteria, including climate, soil, groundwater, vegetation, soil erosion, desertification management and policy evaluation were considered. These indices have been standardized and quantified based on their effect on desertification in the frame by scoring 100 to 200. The qualitative value of each criterion has been obtained by multiplying the weight of the Analytic Hierarchy Process (AHP) and integration of layers based on the weighted linear combination. Finally, the desertification status map has been acquired through multiplying weight to the layer value of each criterion and integrating layers according to the method of weighted linear combination in Geographic Information System (GIS). According to the results, 35.49% of the area of the region falls in a severe class and 64.5% falls in very severe class of desertification. Besides, the climate criterion with a weight of 0.29 has the greatest impact on the phenomenon of desertification and then it goes to the management and soil criteria with weights of soil 0.23 and 0.21, respectively. Therefore, to assess desertification and executive programs to deal with it in the region, considering these criteria are of great importance.
Hormzgan province located in the southern Iran has suffered from water resources shortage and high water losses in the agricultural sector have been led to the serious water crisis in this province. This research aims to use of virtual... more
Hormzgan province located in the southern Iran has suffered from water resources shortage and high water losses in the agricultural sector have been led to the serious water crisis in this province. This research aims to use of virtual water in the arid regions considering the irrigation efficiency. The highest amount of virtual water was found to be 98.83 for citrus fruit production among the horticultural products, 43.7 for barley among the agricultural products, and 5.123 for potato among the cucurbits. The results of exploring the virtual water business showed that the amount of imports and exports of virtual water of the studied products in Hormozgan province was 20434.2 and 1120.9 million M3 respectively. Also, the volume of virtual water of vegetable group is less than 0.07 m3/kg of the product. So, vegetables are placed in the low-consumption with high productivity group. Against, the palm is placed in the high-consumption group due to 3.8 m3/kg volume of virtual water. Results of the value of virtual water of products showed that the values of exported and imported volume of virtual water are 2122.8 and 133.1 million Rials, respectively. Since, Hormozgan province has a little potential in the use of green water, therefore, it is suggested cropping pattern in the province with regard to water supply of green products resistant to water stress, with an emphasis on production with less water requirement and profits, reduce pressure on water resources to achieve the long-term food security and constant agriculture.
Drought in recent years has made high losses to the country that must be reduced by using logical management as much as possible. For this purpose, it is necessary to compare the affected areas by the disaster and locate priority... more
Drought in recent years has made high losses to the country that must be reduced by using logical management as much as possible. For this purpose, it is necessary to compare the affected areas by the disaster and locate priority management actions. The aim of this study is determining the spatial and temporal patterns of drought risks and providing the drought hazard index map of Iran. The monthly rainfall data from 46 stations were selected in this study and the Standardized Precipitation Index (SPI) was deployed at 6 and 12 months’ time scales for generating the map of drought hazard index. The IDW and Natural Break methods were elaborated in GIS environment for zoning and classification, respectively. The results showed that in 6 month time scale, most of the country of the high hazard class and lowest is the average hazard class and for the 12 month time scale, almost half of the country is in very high hazard class and the lowest area is the low hazard class. In general, the possibility of drought in this study showed that when the drought severity increases, its probability decreases.
In the past few decades, an increase in greenhouse gases has caused global climate imbalance on the Earth which is referred to as "climate change". Studies have shown that this phenomenon has direct and indirect impacts on the natural,... more
In the past few decades, an increase in greenhouse gases has caused global climate imbalance on the Earth which is referred to as "climate change". Studies have shown that this phenomenon has direct and indirect impacts on the natural, economic and social systems. Given the importance and necessity of the phenomenon, “Urmia Lake Basin” was selected to study the impacts of climate change on climatic parameters. The large-scale outputs of HadCM3 general circulation models were downscaled using multi-linear SDSM model under the emission scenarios of A2 and B2 for the period of 2050s. Based on the results, the daily precipitation has different fluctuations in the coming period. Using HadCM3 model in the basin showed that the amount of precipitation in the period of 2050s will decrease 0.1mm under the A2 scenario while will increase 0.03 mm under the B2 scenario. Precipitation will show reduction in winter and spring while will increase in summer and autumn under the both emission scenarios. The results revealed that average temperature will increase 1.2 and 1.1 °C under A2 and B2 scenarios, respectively; Also, the highest increase in temperature will be up to 1.5 °C in winter under A2 scenario and 1.4 °C in summer under B2 scenario. The findings of this study can be used to estimate the changes induced in groundwater and surface water resources of the basin, changes in the yield of crops and ranglelands and the occurrence of climate extremes such as droughts and floods in the future.
The study of desertification due to drought in arid and semi-arid areas which have been seriously affected by the challenge of insufficient water resources is very important. The Doroodzan dam basin, located at north of Fars province, is... more
The study of desertification due to drought in arid and semi-arid areas which have been seriously affected by the challenge of insufficient water resources is very important. The Doroodzan dam basin, located at north of Fars province, is one of the main strategic regions in Iran which plays an important role in agricultural productions and have been faced with overexploitation of water resources, land degradation and desertification. So, the current study was conducted to investigate the trend of drought changes in this area during the last four decades. The Standardized Precipitation Index (SPI) and the Streamflow Drought Index (SDI) as meteorological and hydrological drought indices, and also the modified Mann-Kendall test were applied to investigate the drought trend. The results indicated the increasing trend of droughts for both indices. The SDI showed increasing trend for all-time series, while SPI showed this increasing trend for long term droughts (i.e. 9, 12 and 18 months) in significant level of 5%. Also, the comparison of averages of Mann-Kendall Z indicated that SDI was more than three times higher than the SPI which illustrates more hydrological drought intensity than the meteorological one. Also, the increasing trend of the SDI in the middle zones of the basin, which have been affected by intensive human activities and land use changes, is far more, almost 4 times, from the those areas in the upland or outlet of the basin. Therefore, the optimized water allocation in middle areas of basin is recommended to manage and reduce desertification severity.
The aim of current research was to investigate the role of agricultural extension in drought management operations of Tafresh County. This research was a non- experimental type in terms of goal and manipulating and controlling variables.... more
The aim of current research was to investigate the role of agricultural extension in drought management operations of Tafresh County. This research was a non- experimental type in terms of goal and manipulating and controlling variables. From methodological point of view, it is a descriptive and correlational type research while from data processing point of view, it is a correlation type. The statistical population of the study consisted of all farmers, who were about 9061 people in Tafresh County. According to Cochran’s formula, totally 300 farmers were estimated to be appropriate sample size and the questionnaires were completed through the personal interviews. The Cronbach Alpha was used as the measure of reliability which was about 0.832 for the main scale of the study. The validity of the questionnaire was approved by expert judgement of professors and advisors of the Islamic Azad University of Garmsar Branch and University of Tehran. The result of regression analysis showed that the record of effectiveness of being in contact with experts in agriculture, the publications concerning drought management and the participation in the extension visits related to drought management and attending the educational and extension classes in relation to drought management were four major variables with the greatest impact on the rate of applying operation for drought control.
One of the most important environmental problems of Toroud region is the influx of quicksand in to the buildings and settlements of the regions which need precise study and presenting the underlying and practical solutions. For this... more
One of the most important environmental problems of Toroud region is the influx of quicksand in to the buildings and settlements of the regions which need precise study and presenting the underlying and practical solutions. For this reason, the best plant species of arrow sand in Najar Abad Erg have been selected in this research in Najar Abad Erg in south- eastern of Shahrood city by using 2 method of Multiple Criteria- Decision- Making (MCDM) methods including Analytical Hierarchy Process (AHP) and Group Analytical Hierarchy Process (GAHP) methods. Therefore, after specifying the studied region by satellite images and aerial photos, the field studies began and by using transect and Based on one-dimensional method and longitudinal sampling unit, four plant species of arrow sand including Alhagi mannifera, Seidlitzia Florida, Reaumuria Turcestanica and Zygophyllum eurypterum specified and their morphometric characteristics including arrow sand length, arrow sand volume, maximum width of arrow sand, covering crest canopy diameter and plant height have been measured. Then, the best species have been selected by using AHP and GAHP methods. The results indicate that group AHP method has better efficiency than AHP method to defining the suitable species. The Zygophyllum eurypterum with obtain of 0.57 score in group AHP and with obtain of 0.47 score in AHP method have the most effect on stabilizing the quicksand in studied region. According to results, for implementing the plans of quicksand stabilization in studied region; developing the arrows sand of Zygophyllum eurypterum species and then the Alhagi mannifera species are the most important species respectively. So, they will have the maximum efficiency if developing and implement them. The result of this research about quicksand stabilization plans can utilized by environmental planners.
Water scarcity, climate change / global warming, and desertification are three big challenges which human is facing them. These problems have mutual impacts on each other as well. For example, in some regions, climate change causes... more
Water scarcity, climate change / global warming, and desertification are three big challenges which human is facing them. These problems have mutual impacts on each other as well. For example, in some regions, climate change causes frequent drought occurring which results in water shortage and consequently, if drought continues, results in desertification. Arid regions because of their sensitive ecosystem are more susceptible to climate change effects and Yazd province, located in central Iran, is one of the driest parts of the country. In this research, to understand how climate change affects droughts in the region, drought trend in Yazd synoptic station during 1966-2009 is surveyed using nonparametric MannKendall test. Drought, estimated by Reconnaissance Drought Index (RDI), is considered as a result of a decrease in input humidity (rainfall), an increase in output moisture (Potential Evapotranspiration (PET)), or occurring both of them (deficiency in rainfall and higher PET). The 3, 6, 9, 12, 18, and 24 month time series are applied and the results showed a rising trend of drought occurring which caused by precipitation decreasing and PET (calculated by FAO-Penman-Monteith) increasing. In spite of the general drought rising trend, the 1975-1995 period was remarkably humid rather than the rest of the period (i.e.1966-2009) which resulted by PET decrease. Analysis of the major parameters affecting PET revealed that in spite of temperature and sunshine hours increasing in period 1975-1995, wind speed and relative humidity showed a clear decrease and increase, respectively. This caused PET decreasing and consequently humidity increasing. In drought analysis under climate change, therefore, in addition to temperature and rainfall, some other parameters also may be effective and even overcome temperature and rainfall effects.
Desertification is a serious threat to the environment and risk assessment as a strategic tool, allows planning and management to reduce its risk in different time periods. The aim of this study was assessing desertification hazard and... more
Desertification is a serious threat to the environment and risk assessment as a strategic tool, allows planning and management to reduce its risk in different time periods. The aim of this study was assessing desertification hazard and risk management programs in the desert plains of Qasemabad in Bajestan located in Khorasan Razavi province. The assessment of desertification hazard was done by the Iranian version of IMDPA. The desertification risk was evaluated on the basis of desertification hazard map, risk and vulnerability of the environmental elements. The results showed that the risk of desertification with the IMPDA is moderate 22.25 % and severe 77.75 %, respectively. And the factors such as soil erosion, vegetation, groundwater criteria with a weighted average of 3.57, 3.24, 3.3, 2.87, had the greatest impact respectively on the intensity of desertification in the study area. The results also showed that about 52 % of the area in the eastern and east northern parts, was ranked at the rate of high and very high risk. The management plans, strategies and prevention measures such as planting and crop cultivation as well as controlling activities such as increasing vegetation cover, especially with the plants resistant to drought and salinity conditions and in some cases preserving the current condition have the highest importance in terms of desertification risk management.
In recent decades, the quality of groundwater in most areas of Iran has become critical. In this regard, water resources management, especially groundwater resources has a great importance. The aim of existence research was to investigate... more
In recent decades, the quality of groundwater in most areas of Iran has become critical. In this regard, water resources management, especially groundwater resources has a great importance. The aim of existence research was to investigate the temporal and spatial process of underground water quality changes in Ardakan plain, Yazd Province for drinking and agricultural purposes, according to water quality classification systems of Wilcox and Schuler. In this paper, electrical conductivity, sodium absorption ratio (SAR), magnesium, calcium, chlorine, acidity, sulphate and sodium were measured and then interpolated and subsequently classified according to the Kriging, Wilcox and Schuler methods, respectively. The results showed that, except for the parts of the North-East, the rest of the plain have reasonably suitable quality for drinking and with the passage of time, the quality of underground water has been deteriorated. In the case of agricultural, the same setting exists and most of the pollution has been associated with the northern and Eastern parts of the area, which has been expanding over the recent decades. The main reasons of decreasing water quality, on the one hand, can be due to the over-exploitation of water resources as the result of the expansion of urban areas and industrial activities, particularly in the city of Ardakan and Meybod, dominance of traditional agriculture and extensive cultivation of pistachio trees. On the other hand, this reduction in water quality could be attributed to the recent droughts which has diminished groundwater recharge as well.
Salt domes have high impact on groundwater, mineral matters and the soil quality of lowland regions due to intrusion into the saline mass and going up to surface of earth. In this process, a remarkable rate of salt going up to surface of... more
Salt domes have high impact on groundwater, mineral matters and the soil quality of lowland regions due to intrusion into the saline mass and going up to surface of earth. In this process, a remarkable rate of salt going up to surface of earth and entered to lowland regions by the way of various erosional factors and effect on the soil quality. This research aims to investigate the impact of salty dome of Korsia on the soil quality of lowland regions. For this, research region is divided into four sub-regions with regarding to their land uses and distance from salt dome and 22 samples were collected from the region. Ions of Mg, N, K, Na, Ca as well as volume of pH and EC and soil texture of samples of year of 2010 was measured and while the variables of year of 1993 such as Na, Ca, SAR, EC, pH were prepared from Ministry of Agriculture. The significant differences between the various land uses and the change rates of this elements in the land uses during two periods of time were caused to identifying of effective component in the soil quality and classifying of chemical elements was determined by land uses using multivariate statistical methods such as variance analysis, independent T test, factor analysis and cluster analysis, respectively. The results indicated that all variables excepts K, Mn, pH, clay and chemical parameters such as pH and N have significant differences during period of time 1993-2010 according to their land uses; and with regarding to increasing of pH of soil in the periods of time of 1993-2010 in the agriculture land uses and existing of alkaline soils, the effect of salt dome on the soil quality of lowland is clear. The results of factor analysis introduced six components such as Ca, SAR, Na, EC, N and K as the effective variables in the controlling of soil quality of lowlands. The results of cluster analysis showed that the clustering of samples in three clusters is consistent with the land use classification.
Dust is one of the natural hazards that occur mainly in arid and semi-arid area of the world that is one of the major problems in Iran. In this paper, identification of active sources of dust generation in Alborz province using satellite... more
Dust is one of the natural hazards that occur mainly in arid and semi-arid area of the world that is one of the major problems in Iran. In this paper, identification of active sources of dust generation in Alborz province using satellite images and numerical modeling to predict airflow is discussed. LANDSAT 8 satellite sensor (OLI) (from 2013 to 2015) and digital elevation models (DEMs) from the ASTER were received to produce the masks of nonerodible surface and by using vegetation, moisture, roughness indices and images classification those areas separated from the others. Also using field based dust data and HYSPLIT model (normal 5.0 degrees), air flow path in all dust events in 2013 and 2015 was simulated and local dust event was determined. By applying the HYSPILIT matrix model, raster images of events based on the level of dust was produced for local events and specify location of the back flow of air to the ground. The masks of non-erodible surface were used on these images and WLC MCE approach was used to finalize the map of active dust sources. The results showed that the combination of remote sensing and numerical simulation methods and field based data could well show active dust sources.
Seed germination indices can be affected by drought stress in ripening stage of seeds on mother plant. In this study, four water stress treatments (100, 75, 50 and 25% of field capacity (FC)) were imposed during seed maturation of... more
Seed germination indices can be affected by drought stress in ripening stage of seeds on mother plant. In this study, four water stress treatments (100, 75, 50 and 25% of field capacity (FC)) were imposed during seed maturation of Satureja hortensis, and subsequently the effects of treatment on seed germination characteristics of S. hortensis were evaluated using a completely randomized design with four replications. The number of germinated seeds was counted each day and sampled after ten days. Then, percentage, rate of germination, vigor, mean daily germination, final germination percentage, daily germination speed, germination index and length of shoot and root were determined. The results indicated that the drought stress had a significant (P<0.01) effect on germination rate, seed vigor as well as shoot and root length of S. hortensis. The seed germination percentage was significantly affected by drought stress at 5% level. Drought stress during maturity of seeds on mother plants had no significant effects on1000 seed weight, daily seed germination, daily germination rate and germination index. The maximum germination percentage (97.75) was observed in 100% of field capacity and the lowest germination percentage was in the treatment of 50% FC with 87.50. The maximum seed germination rate (10.95) was observed in 50% of field capacity while the lowest seed germination rate (7.94) was observed in 100% FC. The maximum seed vigor (5.15) was obtained in 100% FC that had no significant difference with 75 FC and the lowest seed vigor (4.07) was obtained in 50% FC that had no significant difference with 25% FC.
The lack of sufficient fresh water resources, climate change, lengthy and severe droughts are of the major today’s world challenges particularly in arid and semi-arid regions. In the current conditions, especially in the case of droughts... more
The lack of sufficient fresh water resources, climate change, lengthy and severe droughts are of the major today’s world challenges particularly in arid and semi-arid regions. In the current conditions, especially in the case of droughts and in order to planning for water resources, it is essential to analyze the changes and trends in drought particularly in hyperarid, arid and semi-arid regions of the globe. In this study, the Mann-Kendall statistics were applied to determine the significant and non-significant positive or negative trends in long term drought time series (9, 12, 18 and 24 monthly time scales) in moderate to severe and extreme classes of droughts derived based on the Standardized Precipitation Index (SPI). The results indicated that both significant positive and negative trends can be found in these regions. By increasing the time scales of drought time series, the percentage of significant upward or downward trend grow. For example, in the case of decreasing trend of SPI (increasing in the drought), the percentage of 17.8 for 9 monthly SPI increased to 21.9, 28.48 and 31.71 for the 12, 18 and 24 monthly SPIs, respectively. The increasing trend in long severe and extreme classes of drought can be found in the Middle East and west of America. The upward trends of drought particularly in the Middle East region which is suffered by expensive tensions among the communities can intensify current critical situations. Therefore, more attention should be paid to this subject particularly in the regional and international scales.
This research aims to compare the performances of the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) in terms of the monitoring and trend analysis of the climatic droughts at several... more
This research aims to compare the performances of the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) in terms of the monitoring and trend analysis of the climatic droughts at several synoptic stations located in the coastal areas of Persian Gulf and Oman Sea over 1992 - 2014. To this end, trend analysis of drought was carried out using the traditional Mann-Kendall and Trend Free Pre-Whitening (TFPW) Mann-Kendall tests. The results showed that both indices report the same behaviors, but the SPEI presents higher percentages in different drought classes and a rapid responses to humidity variations at all time scales when comparing to the SPI. Meanwhile, there were significant positive correlations between the two indices at the corresponding time scales such that the highest correlations in most of the stations with the values 0.97 and 0.98 were related to the time scales of 12 and 24 months, respectively. The same results were obtained for the frequency percentages of different classes of the mentioned drought indices. Trend of droughts in the region is generally increasing and the slope of trend for the SPEI is stronger than SPI as the time scale increases. Finally, the use of SPI is not sufficient to monitor droughts in arid and hyper-arid climates of coastal regions, and due to the role of temperature as the limited factor of humidity, the study recommend the use of SPEI for effective and accurate drought monitoring in such regiouse of SPEI for effective and accurate drought monitoring in such regions.
In this study, to evaluate the sediment yield of different geomorphic facies in Aran region, the wind erosion meter and IRIFR model were used. The results of wind erosion meter showed that the most speed of threshold in natural condition... more
In this study, to evaluate the sediment yield of different geomorphic facies in Aran region, the wind erosion meter and IRIFR model were used. The results of wind erosion meter showed that the most speed of threshold in natural condition is belonging to hard crust and dried clay plain with a speed of 13m/s, then puffy and clay-agricultural lands with a speed of 12 m/s, and the lowest threshold speed is 6.5 m/s related to fine-grained loamy - sandy soils of pediment that due to lack of the adhesion, flat, and smooth surface and wind shear impact and blown with wind. The results of wind erosion intensity with wind erosion meter also showed that the clay plains and puffy lands facies are most stable with sediment of 0 to 175.2 tone/km 2 / yr which sorted in erosion class I, and sand sheet with the graveled covered, clay plain and sand dunes are the most sensitive facies, with 5450.09 to 5517.04 tone/km2/ yr sediment equivalent classified in erosion class IV. While the results of the IRIFR model showed that the most stable facies are agricultural lands with 415.1 ton/km2/yr sediment erosion that classified in the erosion class II and facies sand sheet and sand dune the most sensitive facies, that with 1168.6 ton/km2/ yr sediment equivalent classified in erosion class IV. According to statistics obtained from the two models, it is concluded that except to the puffy land and clay plain there was not significant differences among the rest of facies.
This paper aims at comparing the accuracy of regression, artificial intelligence, and adaptive neuro-fuzzy (ANFIS) interpretation methods in estimating wind speed in the Sistan region. To this end, we used the daily weather information... more
This paper aims at comparing the accuracy of regression, artificial intelligence, and adaptive neuro-fuzzy (ANFIS) interpretation methods in estimating wind speed in the Sistan region. To this end, we used the daily weather information obtained from Zabol synoptic stations during a five-year period (2010-2015). MATLAB software was used for modeling based on artificial neural network. On the other hand, DATA FIT software was used for modeling based on regression methods. The methods’ accuracies were estimated using mean square error statistics, comparison indexes, and mean error. Based on sensitivity analysis results; variables such as daily temperature mean, mean relative humidity, sunshine hours, and evaporation from pan were regarded as input variables of regression and artificial intelligence methods. Wind speed was considered as output variable. Based on the results, mean daily temperature and mean relative humidity had the most and the least effect on wind speed in Sistan (0.42 and 0.25 respectively). Neuro-fuzzy method with Gaussian function was the most accurate method in estimating wind speed (error squares mean of 2.56). The same statistic for regression method is 4.44. The correlation of regression method (0.45 and 0.51) is less than those of multilayer perceptron method and Neuro-fuzzy method (0.51 and 0.52). So, it is suggested that Neuro-fuzzy method can be used for more accurate estimating wind speed in Sistan region. With accurate estimation of this variable, we can hinder the devastative effects of wind and use it as an effective source of energy.
Wind erosion and generation of dust is one of the most important problems in the Yazd province. To control this phenomenon and overcome the damages a lot of investment has been done for the implementation of many successful and... more
Wind erosion and generation of dust is one of the most important problems in the Yazd province. To control this phenomenon and overcome the damages a lot of investment has been done for the implementation of many successful and unsuccessful projects across this province. Analysis of erosive winds and estimation of the Resultant Drift Direction (RDD) of sand flow is the fundamental study by which can lead to a more successful implementation of projects, to control wind erosion. In this study, by taking advantages of Wind-rose, Storm-rose and Sand-rose has been analyzed wind speed, wind direction and calculation of wind drift potential (DP) to represent a landscape of wind erosion in the Yazd province and with the results of these analysis, the Resultant Drift Direction (RDD) of sand flow and dust be estimated. The results showed that most of the erosive winds in the Yazd province occur in the spring and summer and the lowest erosion occurs in autumn. The results as well revealed that the average percentage of erosive winds which are capable of producing dust are between 6.4%, in Yazd city, and 23.6%, in Herat city, and on average, in 44 days there is the possibility of dust in the Yazd province. Therefore, although the prevalence of erosive winds with speed more than 6 meter per second generally does not exceed 14% but, it has the most important role in the occurrence of the wind erosion and dust generation in the Yazd province and the mobility of a large amount of dust is generally from the southwest and west to the north east and east.
Different surface covers such as soil, rock, plant and etc, lead to be created different climate conditions in small scales by impacting on the adjacent atmospheric elements. The greatest difference tangibly in land surfaces and air... more
Different surface covers such as soil, rock, plant and etc, lead to be created different climate conditions in small scales by impacting on the adjacent atmospheric elements. The greatest difference tangibly in land surfaces and air temperatures were observed in arid and desert regions on hot days, which can have significant microclimate and ecological effects on environment. In this study, 8 different land surface cover including, green plant cover, dead plant cover, arable soil, cement surface, non-arable soil, pavement, asphalt and dark metal surface were measured using two types of mercury and digital thermometers to compare between the measured temperature at the Yazd meteorological station and the temperature of different land surfaces, in June and July, 2016. Then, the land surface temperatures were compared to each other and also compared with the air temperature measured at the Yazd meteorological station. Based on the results, the highest measured temperature reaches to above 70 °C in asphalt cover and the lowest surface temperature of 47.4 °C were recorded in plant surface. According to the result of Kolmogorov Smirnov test, there are a significant difference between the different land surfaces and the air temperatures (R2= 0.86) at 5% level during the measured period. Generally, asphalt and plant surfaces showed the highest (23 °C) and the lowest (5 °C) thermal differences with air temperature. Concluding, different land surfaces show different thermal patterns.
Ground water is one of the major resources of fresh water needed for humans, especially in arid areas. It will be seriously threatened in future due to climate change and global warming. The purpose of this study is to examine the effects... more
Ground water is one of the major resources of fresh water needed for humans, especially in arid areas. It will be seriously threatened in future due to climate change and global warming. The purpose of this study is to examine the effects of climate change on groundwater resources in the Kerman-Baghin plain. Accordingly, climate prediction at 2055 horizon (2065-2046) was used by the atmospheric general circulation model HadCM3 with A2 emissions scenario. Also groundwater table during the years (1986 -2009) and the quality situation (salinity) over the years (2003-2009) were studied. The results of LARSWG model showed that the average annual rainfall at the 2055 horizon will be reduced about 3.6 mm. Also the annual maximum and minimum temperatures will increase during the 2055 horizon, 2.8°C and 2.8 °C, respectively. Assessing of unit hydrograph and chemograph in Kerman- Baghin plain highlighted a drop in the water table (0.89 meter depletion per year) and increase of aquifer salinity. According to the results of atmospheric general circulation model (HadCM3), this trend in the water table and increase in aquifer salinity expected to be continued.
In recent decades, the increase of temperature has caused the disturbance of climatic balance of the earth and extensive climate changes which is called climate change. The aim of this study is to predict the climate changes using... more
In recent decades, the increase of temperature has caused the disturbance of climatic balance of the earth and extensive climate changes which is called climate change. The aim of this study is to predict the climate changes using statistical downscaling model (SDSM) based on A2 scenario over future periods. Daily precipitation, minimum and maximum temperature data of Kermanshah synoptic station, for two periods 2015-2040 and 2040-2065, were predicted and compared with the baseline period. The first 27 years of data (1988-1961) were used for calibration and the second 12 years (1989-2001) were used for validation of the model as well. The results showed that based on the A2 scenario, in the periods of 2015- 2040 and 2040- 2065, the average annual precipitation decreases, the average minimum and maximum temperature increases compared to the baseline period in the Kermanshah synoptic station. Since the precipitation reduction and temperature increase are one of the main factors of desertification, so it is necessary for decision makers and planners in Kermanshah province to adopt necessary solutions for mitigation and adaptation with new climatic conditions.
Using of flood to supply plant water requirement for its growing and decreasing of flood damages is possible by many different methods. By using of water spreading systems, seasonal flood in susceptible land will be spread with different... more
Using of flood to supply plant water requirement for its growing and decreasing of flood damages is possible by many different methods. By using of water spreading systems, seasonal flood in susceptible land will be spread with different effects on groundwater, plant cover and soil on these lands. In order to measure the effect of water spreading system on changes of vegetation, soil salinity and organic carbon in Miankooh floodwater spreading area, 40 random plots of 2 sq. meter were taken in floodwater spreading area and 20 points were selected outside the floodwater spreading(control areas) and vegetation were changes measured. Meanwhile, to investigate soil salinity and organic carbon changes, 8 profiles were taken from four depths ranges including 0-10, 10-20, 20-30, 40-60 cm in the area affected by flood and sediment and some points were selected in outside floodwater spreading(control areas). The statistical results indicated that floodwater spreading have significant effects on vegetation cover and salinity reduction (in depth=0 to 10cm) while no significant effect on soil organic carbon. Generally floodwater spreading from one hand can reduce soil salinity and consequently increase amount of plant cover in arid and semi-arid regions but on the other hand, high volume of flood and deposition of sediments, reduce the efficiency of water spreading over the time.
Human pressures on the world’s landscapes are accelerating at unprecedented rates. In response to these pressures, making the need for sustainable landscape management and planning even more urgent. To have a continuous and sustainable... more
Human pressures on the world’s landscapes are accelerating at unprecedented rates. In response to these pressures, making the need for sustainable landscape management and planning even more urgent. To have a continuous and sustainable utilization of rangelands these changes must be recognized and managed. Landscape Function Analysis (LFA) is a monitoring procedure that assesses the degradation of landscapes, as brought about by human, animal and natural activities, through rapidly assessing certain soil surface indicators which indicate the biophysical functionality of the system. Indicators of soil surface characteristics and rangeland functional attributes assist researchers in judging the effects of their applied management activities. In this research, three rangelands with similar ecological characteristics were studied in order to compare their health and stability. The aim is to determine qualification of sustainability and rangeland health attribute by the LFA method. It was tried to answer this question that similar ecological and climatic conditions, different management practices how affect on sustainability and health indicators? This purpose was done by three indices of stability, permeability and nutrient cycle for each study region. The differences between these indices was significant. The results showed that Espiro rangeland is stable than two others. Changi rangeland need more reformative activities that rangeland managers have to recognize these relations and proceed.
Landscape ecology is one of the youngest branches of ecology science, and especially deals on the study of landscape composition ,structure and function. Landscape elements are such as patches, corridors, matrix along the border and... more
Landscape ecology is one of the youngest branches of ecology science, and especially deals on the study of landscape composition ,structure and function. Landscape elements are such as patches, corridors, matrix along the border and ecotons. Landscape metrics are algorithms for quantifying the spatial characteristics of patches, classes or entire landscape mosaics, and the best way to compare different landscape requirements. Due to this, the aim of this study was to quantify landscape patterns and the possibility of breakdown of plant communities using landscape metrics. Metrics that were used in this study the number of patch, class area proportion in the landscape, mean patch size ,edge density, mean shape index, mean patch fractal dimension and total edge in the class level and Shannon diversity index in the landscape level. Metrics listed for vegetation map and morphology units were calculated using the patch analyst extension for Poshtkooh rangelands of Yazd .Then, using the principal component analysis were determined the important metrics for the separation of plant communities .The results of the principal component analysis for the separation of class in morphology units map showed that edge density metric have the greatest impact but in the vegetation map landscape metrics, were equally important and more importance metric could not be determined and compared to separation the units of land shape in the morphology units map were less separation. Finally, with using of discriminate analysis, was determined the differentiation function and metrics that create separation between the plant communities and land classes. Discriminate analysis showed that the number of patch metric, edge density and mean patch fractal dimension can be separated plant communities and classes in the map, units are less resolution.
Data recorded in the thermal band satellites, are commonly used in the thermal characteristics of different phenomena, especially in desert areas. Classification is one of the most important steps in the use of satellite imagery. In this... more
Data recorded in the thermal band satellites, are commonly used in the thermal characteristics of different phenomena, especially in desert areas. Classification is one of the most important steps in the use of satellite imagery. In this study, using ASTER data TERRA satellite on 22 August 2001, East and North East Kashan Salt Lake, were studied to find the role of quantity bands of this sensor to increase the resolution accuracy of phenomena in the maximum likelihood (MLK) and support vector machine (SVM). For this purpose, after the initial radiometric and geometric corrections, eight approaches were chosen with different band combinations step by step in order to investigate the quantitative role of each band to increase the classification accuracy and then the classification accuracy using Kappa index, user and producer accuracy were evaluated. The classification algorithm results showed that the support vector machine algorithm rather than maximum likelihood algorithm has slightly better results. Generally, the use of all spectral and thermal bands (14 bands) had a highest accuracy for both Kappa support vector machine algorithm (83.04) and maximum likelihood (90.82). While the Kappa accuracy by 15% in both algorithm with elimination of all thermal bands (bands 10, 11, 13.12 and 14) was reduced. The maximum likelihood algorithm had the greatest impact on increasing the accuracy of Kappa index bands of thermal 14 (between 8 to 10 percent) and in the support vector machine algorithm bands of 10 and 14 (7%). Finally, it was proven that ASTER sensor due to wide spectrum range in the wavelengths of thermal infrared has very high potential in increasing accuracy coefficient of classification Kappa.
Drought is one of the most important natural disasters that is effective in different parts such as; natural resources, surface and subsurface water resources and etc. Notice to the changes trend of drought and its forecasting, can be... more
Drought is one of the most important natural disasters that is effective in different parts such as; natural resources, surface and subsurface water resources and etc. Notice to the changes trend of drought and its forecasting, can be effective in planning of drought control and reduction of drought impact. In this study climate data of 7 stations of southwest of Iran from 1980 to 2014 was used and the Intensity of
seasonal drought was calculated based on RDI index. Then drought index predicted from 2015 to 2019 using time series models and ITSM software, then the changes trend of drought based on parametric and non-parametric tests were evaluated. According to results in Abadeh, Shiarz and Fasa stations MA (5) Innovation, in Bandar Abass station AR (15) Burg, in Bandar Lengeh station AR (15) Yule-Walker, in Boushehr station MA (5) Hannan-Rissanen and in Jask station AR (13) Burg model were the best time series model that fitted in data. Correlation coefficient between observed data and predicted data, P- Value of Ljung – Box test, white noise of models and ACF and PACF Residual of models showed that predicted models were Reliable. Results showed that the changes trend of seasonal drought in all stations from 1980 to 2014 and 1980 to 2019 periods were non-significant at 0.95 level based on parametric and non parametric statistical methods. However slop of changes trend in (1980-2019) period was more than (1980-2014) period.
seasonal drought was calculated based on RDI index. Then drought index predicted from 2015 to 2019 using time series models and ITSM software, then the changes trend of drought based on parametric and non-parametric tests were evaluated. According to results in Abadeh, Shiarz and Fasa stations MA (5) Innovation, in Bandar Abass station AR (15) Burg, in Bandar Lengeh station AR (15) Yule-Walker, in Boushehr station MA (5) Hannan-Rissanen and in Jask station AR (13) Burg model were the best time series model that fitted in data. Correlation coefficient between observed data and predicted data, P- Value of Ljung – Box test, white noise of models and ACF and PACF Residual of models showed that predicted models were Reliable. Results showed that the changes trend of seasonal drought in all stations from 1980 to 2014 and 1980 to 2019 periods were non-significant at 0.95 level based on parametric and non parametric statistical methods. However slop of changes trend in (1980-2019) period was more than (1980-2014) period.
The herbicidal properties of some plants species can be exploited successfully as a tool to reduce the herbicide application. Wild plant species, including medicinal herbs, usually contain much higher levels of chemicals compounds than... more
The herbicidal properties of some plants species can be exploited successfully as a tool to reduce the herbicide application. Wild plant species, including medicinal herbs, usually contain much higher levels of chemicals compounds than the cultivated crops; therefore it can be used to control the weed species. The current study was conducted inorder to evaluate the herbicidal properties of Capparis spinosa on Malva parviflora in both laboratory and greenhouse conditions. A factorial experiment was used with three replications. Evaluated factors including used parts of plant (foliage, root) as well as plant material amount (four concentrations of aqueous extract; 0, 0.6, 0.9, 1.25 g dry weight per 100 milliliter water; in laboratory condition and four amount of plant powder; 0، 4، 8، 12 g dry weight per 1000 g soil; in greenhouse condition). The results indicated that, in laboratory condition, with increasing concentration of Capparis spinosa aqueous extract from 0 to 12%, mean time to germination of M. paryiflora increased progressively from 1 to 1.4 and 2.2 days, respectively. At 1.25% aqueous extract concentration, the germination percentage, root and soot length as well as root and shoot dry weight diminished 87, 90, 91, 83 and 73%, respectively, when compared to the control. Also in greenhouse condition, the effects of Capparis spinosa powder added to the soil on measured parameter were significant. In the soil treated with 12g powder, seedling length of Malva parviflora in the second week of growth reduced about 47% when compared to the control. Overall, the results revealed the possibility use of herbicidal properties of Capparis spinosa for biological weed control and therefore reduce application of chemical herbicides.
Trend analysis and understanding of the historical volatility in the climate system, is one of the most important requirements in research on climate change. In order to study the trend, there are different methods covering parametric and... more
Trend analysis and understanding of the historical volatility in the climate system, is one of the most important requirements in research on climate change. In order to study the trend, there are different methods covering parametric and non-parametric approaches. The non-parametric Mann - Kendall methods are widely used to study the hydrological series. But the autocorrelation in the hydrological series increases probability occurrence of type I error. In this study in order to evaluate the effects of autocorrelation, the time series trend without excluding the effect of autocorrelation and then by applying TFPW method and excluding the effect of autocorrelation were analyzed. The results showed that by removing the effect of autocorrelation, number of stations with significant negative trend was decreased. Therefore, in annual and monthly scales, none of rainfall data series in 22 rain gauge stations were significant at the 95 percentage confidence level. Therefore, it revealed that in evaluating the hydro-climatological data, the effects of autocorrelation must be removed from time series to provide accurate and reliable results.
One of the important criteria of desertification is water and irrigation which is influenced by various indices, all of which are affected by human activities. In this research, in order to determine the most effective water and... more
One of the important criteria of desertification is water and irrigation which is influenced by various indices, all of which are affected by human activities. In this research, in order to determine the most effective water and irrigation index in the desertification of Kashan and Aran Bidgol plains, and to show the importance of human activities in desertification, 13 water and irrigation indices of IMDPA model were investigated after on the field operations and collecting the necessary data. The GIS map of water and irrigation index based on work unit was extracted. The results showed that 84.58 percent of the study area is located in the intense class, and 15.42 percent in the medium class of desertification. The highest numerical value is related to the work units of the sandy plains located on Epandage plains, residential and industrial land, and agricultural land of covered plains and Epandage plain with intense class, respectively. Analyses performed on the numerical values of weight average indices affecting water and irrigation criteria in the area indicate that the index of water pumping hours is the most influential index on accelerating rate of desertification in the region.
If the wind speed got fasterthan soil erosion threshold and soilsurface with plants,residuals and surface roughness are protected, then the process will lead to wind erosion. The necessity of estimation of erosion in soil protection... more
If the wind speed got fasterthan soil erosion threshold and soilsurface with plants,residuals and surface roughness are protected, then the process will lead to wind erosion. The necessity of estimation of erosion in soil protection planning is important issue and there are different methods for estimation of erosion which have presented in current study. The rate of erosion and sedimentation of different work units (salty pan land, puffy land, arable and reforested saxual and eroded marls) were analyzed via IRIFR and RWEQ. Comparing of the results of two models showed that the general trend of erosion on studied faces was nearly the same (i.e. it was maximum in salty pan land faces while minimum in wheat farm lands) but numeral values of wind erosion in RWED model in some faces were less than the results of IRIFR and in others were higher. This different is mainly due to the technological variation in wind erosion calculation by the models. Based on RWEQ model, the average range of wind erosion in whole area was 15.7ton/ha/Y (class II-III). Assessments of different landscapes via IRIFR model showed that except saxual faces, lack of vegetation was the most effective reason on wind erosion of the landscapes. Also, the results showed that in case of shortage of data, especially for wind data in Iran, using of RWED model in order to assess the quantity of wind erosion and annual and monthly monitoring will be suitable.
This research has tried to take advantage of the two-field models in order to assess the remote sensing data capacities for modeling soil degradation. Based on the findings, pre-processing analysis types have not shown significant effect... more
This research has tried to take advantage of the two-field models in order to assess the remote sensing data capacities for modeling soil degradation. Based on the findings, pre-processing analysis types have not shown significant effect on accuracy of the model. Conversely type of field model used and its indicators and indices have a large impact on the accuracy of modeling. Also using some remote sensed indices such as Iron Oxide index and Ferrous Minerals index can help to improve the modeling accuracy of some field indices of soil condition assessment. According to the results, using time-series remote sensed data compared to the use of single date data can improve the model capacities significantly. Alse, if artificial neural networks used on single date remote sensed data instead of multivariate linear regression, accuracy of the model can be increased dramatically because it helps the model to take the form of nonlinear. However, if time series of remote sensed data used, the accuracy of the artificial neural network modeling is not much different than the accuracy of regression model. It turned out to be contrary to what is thought but according to the results, increasing the number of inputs to artificial neural network modeling in practice reduces the actual accuracy of the model.
Due to the functioning of the ecosystems to support life on Earth, they play an important role. In recent years, natural resources economists have been engaged in valuation and measuring the role of natural resources in providing human... more
Due to the functioning of the ecosystems to support life on Earth, they play an important role. In recent years, natural resources economists have been engaged in valuation and measuring the role of natural resources in providing human welfare. They had made considerable progress in valuation of natural environment and ecological services of ecosystems. This research studies people's willingness to participate in protecting and reviving Noush Abad desert area, using the conditional valuation and tow-dimensional, dual choice questionnaire. To estimate the willingness to pay, logit regression model was used based on the maximum likelihood method and the parameters of the model were estimated. The results suggest that age, shortage of water resources (tapping too much water), family income have significant positive effects while agricultural activity, animal husbandry, poor management and number of family members have a significant negative effect on the people's willingness to pay. Also, the factors such as age, education had positive impact while grazing has a negative impact on people's willingnessto pay, but these variables were not significant at the appropriate level. The average willingnessto pay of the deontologist and consequentialist people in thisstudy to participate in protecting and reviving the deserts of Noush Abad is estimated to be 100000 and 99720 Rials, respectively.
One of the key components of energy and hydrological processes issoil moisture, which is measured indirectly, because of exiting some problems in measuring directly. Some existing methods such as thermal inertia, vegetation indices,... more
One of the key components of energy and hydrological processes issoil moisture, which is measured indirectly, because of exiting some problems in measuring directly. Some existing methods such as thermal inertia, vegetation indices, temperature and water indices (e.g. NDWI) has certain limitations such as difficulties in capturing images of day and night times, and differences in method of calculating of thermal inertia for different hours in a day. Therefore, finding a new method for calculating of soil moisture based soil temperature or water and soil spectral changes is very necessary. Although soil moisture is not calculated directly in the Surface Energy Balance Algorithm for Land (SEBAL), since all parameters that have effect on soil moisture changes, consider for calculating evapotranspiration in SEBAL, this model can be used to calculate soil moisture. Jarghoye-Sofla, as the study area, is located adjacent to the Gavkhoni playa, Isfahan province. The study area, has faced with declining in soil moisture, as a result of climatic fluctuations, and drying of the wetlands in recent years. The purpose of this research is assessing of the remote sensed based surface energy balance model, and evaluation of biophysical parameters derived from satellite imagery to estimate soil moisture. Data used in this research, consisted of MODIS satellite images and measurements of 33 soil samples taken at depth of 0-30 cm. By measuring point soil moisture, and calculating volumetric soil moisture, the rate of evapotranspiration was estimated using the SEBAL model. Then, correlation between the parameters used in the SEBAL and ground measurements of soil moisture was evaluated. Results show high correlation between parameters of the SEBAL and soil moisture. The highest correlation was determined between the SEBAL algorithm daily evapotranspiration and soil moisture for days of 16 and 17 November, 2014 with values of 0.51 and 0.68, respectively.
Groundwater is known as one of the most valuable natural resources which play an important role in providing water supply in arid areas. In this study, multi-criteria decision-making (MCDA) methods were used for sensitivity analysis of... more
Groundwater is known as one of the most valuable natural resources which play an important role in providing water supply in arid areas. In this study, multi-criteria decision-making (MCDA) methods were used for sensitivity analysis of the effective parameters in groundwater potential prediction based on the lithology, annual rainfall, drainage density, lineament density and land slope parameters in Ghorveh-Dehgolan plain as a case study. The normalized weights of the parameters were determined based on the paired comparisons of AHP approach. After preparing the groundwater potential prediction map, validation of the model was conducted by using the pumping tests data of 20 wells in the study area. Sensitivity analysis of the effective parameters in groundwater potential prediction was measured using the elimination method and finally accuracy of the maps was evaluated. The results of the sensitivity analysis showed that all parameters have a positive impact on the accuracy of the groundwater potential prediction while the best accuracy was obtained by combination of all layers (85%), and the worst accuracy resulted when the lithology was eliminated from the decision layers (60%). Therefore, the lithology parameter through effects on physical properties such as density of lineaments and faults, porosity and permeability has the highest impacts on the accuracy of groundwater potential prediction. The results also revealed that rainfall and slope variables, in despite of their little changes in a plain, are effective in accuracy of groundwater potential prediction.
Environmental pollution as technologic desertification factor is the most important challenging issue in industrialized and developing societies. Due to the presence of several mineral sites in Bafgh, the most important reason of... more
Environmental pollution as technologic desertification factor is the most important challenging issue in industrialized and developing societies. Due to the presence of several mineral sites in Bafgh, the most important reason of desertification is pollution caused by industries and mines. This study aims to determine the emissions effluent from processing iron ore in the Bafgh region. Totally, 16 samples of effluent were taken over the period 2008- 2013, and 18 parameters were measured in the laboratory. After testing the related data normality and variance analysis, index of PI, IPI and MCd were determined for the collected data. The results showed that 27.7% of the parameters are without non-significant year changing while 72.3% of the parameters have significant annual changes. The results for the PI index showed that 66.6% of the parameters show less contamination level and 33.4% of the parameters are at moderate to high contamination level. According to the results obtained for the IPI and MCd index, Nitrate (NO3) and Sulfate (SO4) classified at the moderate and high levels of pollution and determined as the contaminants of effluent from processing. Considering desert ecosystems are sensitive and fragile, it is suggested to determine the concentration of pollutants in the wastewater processing parameters with deposited sediments to study the feasibility of removing contaminants by phytoremediation. It might be useful to determine desertification intensity in Central Iron Ore Company marginal and desert regions in Bafgh with the conventional models and taking into account the environmental pollution, Nitrate and Sulfate indices.
The aim of this study was to evaluate the efficiency of artificial neural networks in supplying predictive maps of plant species habitats distribution in Qum province rangelands, Iran. For this purpose, soil and vegetation sampling was... more
The aim of this study was to evaluate the efficiency of artificial neural networks in supplying predictive maps of plant species habitats distribution in Qum province rangelands, Iran. For this purpose, soil and vegetation sampling was done after determination of homogenous unit by combining of slope, aspect and elevation maps and environmental variables maps were prepared using geostatistics and GIS. To prepare the artificial neural network models, the best network structure, was determined following required data preprocessing (normalizing data and partitioning of data into three sets, training, test and validation), improving adjustable parameters (such as transfer function, learning rule, the number of hidden layers, number of hidden layer neurons) and using statistical parameters calculated in the test phase (MSE). After selecting the optimal network, simulations were performed to estimate the probability of the presence or absence of the species and continuous probability maps of the presence or absence was prepared at each species habitat using Arc GIS. Then the optimal threshold was determined using equal sensitivity and specificity method and the compliance between predicted and actual maps were examined by calculating kappa. Based on the results, the most accurate prediction models were obtained for all habitats using sigmoid transfer function and the Levenberg Marquardt algorithm. The results also showed that habitat predictive and actual maps of Artemisia sieberi, Halocnemum strobilaceum, Tamarix passerinoides, Seidlitzia rosmarinus and Artemisia sieberi have excellent, very good, good, fair and poor compliance, respectively. These results indicate that the multilayer perceptron has acceptable accuracy in the modeling and estimation of the geographical distribution of the studied species habitat and if the network input variable be chosen properly, the network can simulate presence or absence of plant species with high accuracy.
Land surface changes accurate and timely detection provides a basis to better understand the relationships and interactions between human and natural phenomena for appropriate management and optimal use of resources. Trend of... more
Land surface changes accurate and timely detection provides a basis to better understand the relationships and interactions between human and natural phenomena for appropriate management and optimal use of resources. Trend of environmental issues such as land degradation, ecosystem potential reduction and desertification can be realized by monitoring land use changes in temporal intervals. The current study is aimed to monitor land use changes of Daryacheh Namak area to recognize desertification in a 36 year period using Landsat satellite data, remote sensing and GIS techniques. The results of land use changes monitoring shows that Kavir-e-Namak land use area had little changes and has increased about 5.26 km2. The area of salty and bare lands has increased (457.13 km2), rangeland area decreased (380.3km2), sand dune area decreased completely linear (194.57 km2), and finally the area of agricultural land has increased (118.35 km2). Final results showed that satellite images are of unique potential in extracting land uses. It also became clear that Landsat satellite imagery with a spatial resolution of 10 meters have the required ability of land use maps extraction in the regional scale.
Mulch is one of the most common materials for soil stabilization which prevents wind erosion and dust emissions. In this respect, the sustainability of mulches against corrosive environmental factors is important for selection. In this... more
Mulch is one of the most common materials for soil stabilization which prevents wind erosion and dust emissions. In this respect, the sustainability of mulches against corrosive environmental factors is important for selection. In this study, the resistance of some abiotic mulches was examined in simulated desert conditions against pressure by pocket penetrometer at different temperatures. Also, to evaluate the amount of surface leaching, the mulches were tested against spraying water as well. Treatments include 13 types of mulches, nano-polymer mulch, sand, stone powder, sludge and clay soils. Two types of eroded soils including moderate and severe soil erosion and three levels of temperature including ambient temperature, 50 ºC, 60 ºC all of them with three replications were studied. The results showed that sprayed polymers on severe soil erosion and under both 50 ºC and 60 ºC temperatures had the maximum compressive strength. Also the results of spraying water on the treatments showed that polymeric mulch was more resistant against leaching than others.
In this study, the groundwater level depletion and electrical conductivity (EC) were chosen to assess the water quality and quantity changes in Kashan plain, Iran. The relevant hydrographs were drawn using Thiessen polygons based on the... more
In this study, the groundwater level depletion and electrical conductivity (EC) were chosen to assess the water quality and quantity changes in Kashan plain, Iran. The relevant hydrographs were drawn using Thiessen polygons based on the piezometric data. Moreover, the groundwater depletion, the elevation contour line and iso- electrical conductivity maps were provided using GIS. Also, the relation between EC and Anions and Cations (such as Ca2+, Mg2+, K+, Cl-, Na+, SO42-, HCO3-) were determined. The calculated Standard Index of Annual Precipitation (SIAP) in five meteorological stations showed that normal precipitation has the most percentage of frequency. Also, the results of drawn maps showed that the groundwater flows from south of the plain towards the Kavir in the north part of the plain. The most depletion of groundwater level and the withdrawal have also occurred in the south and south-eastern parts of the plain mainly due to the concentration of agricultural lands. Electrical conductivity has direct relation with concentration of ions in all cases, except bicarbonate. According to the hydrographs; the average level of groundwater has decreased 10.02 meters over 19 years and the groundwater level depletion has consequently decreased poor water quality.
Based on the scientific literature in the realm of sustainable water resources management, some researchers have highlighted the impacts of economic, social and environmental driving-forces, yet ignored analysis of effective strategic... more
Based on the scientific literature in the realm of sustainable water resources management, some researchers have highlighted the impacts of economic, social and environmental driving-forces, yet ignored analysis of effective strategic internal and external factors through the basin. Meanwhile, the others have considered strategic factors rather than sustainable development paradigm. Therefore, the current research has constructed a framework to promote the quantitative policy-making by using the internal and external strategic matrix along with the sustainable development together in Lake Urmia Basin. Due to the fact that, conventional quantitative strategic planning matrix (QSPM) could not involve above mentioned considerations simultaneously, the Modified QSPM (MQSPM) was proposed to include the socio-economic and environmental factors besides internal and external factors. According to the results, the most attractive policy belonged to Conservative strategies (included weaknesses and opportunities). Moreover, capability of watershed management to deal with 10 out of 13 weaknesses was not satisfying. The potential of regional watershed management to deal with 11 economic, five social, and nine environmental challenges contributed to the weaknesses was estimated inappropriate. In addition, climate change and drought were not evaluated as the most critical threat of the basin, while economic crises and low investment security was determined as the most critical threat. Actions’ ranking for environmental security conservation indicated that high ranks belonged to the integrated watershed management. Due to the simplicity and suitable performance of MQSPM, this matrix is suggested for future research work on identifying and evaluating the strategic factors.
Nowadays, desertification is one of the important ecological crises affecting the world. We require a proper understanding of causes and processes of desertification to control the serious phenomenon in the global and regional scales. In... more
Nowadays, desertification is one of the important ecological crises affecting the world. We require a proper understanding of causes and processes of desertification to control the serious phenomenon in the global and regional scales. In comprehensive management, the monitoring content is systematic collection and storage of data from activities and strategies that provide assessment and report about the overall condition of the study area. In this study, using AHP and GIS techniques, the desertification process was assessed by IMDPA model in 7864.5 ha of Zarabad region in the southeastern Iran. The results of analysis showed that desertification benchmarks and indicators in the three periods had a nonlinear trend of desertification process in the region so that the numerical value is equal to 2.73 in the period 2001-2004 but In the period 2004-2007 the figure has decreased that is show decreasing trend of desertification in recent years and the main reason for the improvement was climatic parameters such as rainfall. The numerical value in the period 2007-2010 is 2.55 shows an increasing trend of desertification. As the result show that climate benchmark is dominant over three periods and classified in high grade. Among the indicators studied, Transouaridity index and annual precipitation index had the maximum effect with the values of 3.81 and 3.4 while sodiumabsorption ratio value was 1.17 with the least impact on desertification. Among two water quality indices in the area,the electrical conductivity has greater influence than sodium absorption ratio that it directly related to the increasedexploitation of groundwater and increased salinity in the studied region.
Application of provenance method by tracers or fingerprinting has been demonstrated as a successful and effective way to determine the sediment sources. According to this method, physical, geochemical and biogenic features of sediment are... more
Application of provenance method by tracers or fingerprinting has been demonstrated as a successful and effective way to determine the sediment sources. According to this method, physical, geochemical and biogenic features of sediment are used to determine the sediment sources and their importance. The main aim of this research is determining the contribution of different facies using the hybrid model in sediment supply for sand dunes of Ashkzar erg. For this aim, 65 surface samples from the sources region facies and 8 samples from the sand dunes were collected and the particles less than 62.5 micron, as the target, were tested. In order to measure the geochemical elements including rare earth elements (REE) and trace element, the ICP-AES was used. Then, ICP-MS was used to measure Strontium (87Sr & 86Sr)
and Neodymium (143Nd &144Nd) isotopes. The indices of rare earth elements were calculated and the elements, REE indices and isotopes were used as tracer. Then, initial choice and optimal combination of tracers were done by the statistical methods including one-way ANOVA, Kruskal-Wallis and discrimination analysis. Finally, contribution of the various facies on sediments supply was determined using hybrid models. The results showed that Rubidium (Rb), Cerium (Ce) and Strontium (Sr) were determined as the optimal combination. Moreover, the results of hybrid models showed that the distribution facies of fine sandy plains & dry river bed, fans & dry river bed, Kelot, farmlands, Neogene marl hills and Sebkha were 27, 22.7, 24.4, 13.26, 6.4 and 6.24 % respectively. Performance of the model was 0.999 indicating it's accurate and appropriate results.
and Neodymium (143Nd &144Nd) isotopes. The indices of rare earth elements were calculated and the elements, REE indices and isotopes were used as tracer. Then, initial choice and optimal combination of tracers were done by the statistical methods including one-way ANOVA, Kruskal-Wallis and discrimination analysis. Finally, contribution of the various facies on sediments supply was determined using hybrid models. The results showed that Rubidium (Rb), Cerium (Ce) and Strontium (Sr) were determined as the optimal combination. Moreover, the results of hybrid models showed that the distribution facies of fine sandy plains & dry river bed, fans & dry river bed, Kelot, farmlands, Neogene marl hills and Sebkha were 27, 22.7, 24.4, 13.26, 6.4 and 6.24 % respectively. Performance of the model was 0.999 indicating it's accurate and appropriate results.
Spraying petroleum mulch has been one of the common measures of mobile sand stabilization endeavors over the last three decades. However, the consequences of mulch on the endemic vegetation species, vegetation recovery and soil attributes... more
Spraying petroleum mulch has been one of the common measures of mobile sand stabilization endeavors over the last three decades. However, the consequences of mulch on the endemic vegetation species, vegetation recovery and soil attributes improvements have not been fully understood. This study seeks examining the effects of petroleum mulch on the sandy deserts of Sarakhs located in Khorasan Razavi province. The sampling was arranged as the randomizedsystematically by dividing the area of operation into control and treatment plots and the sampling was performed in the key areas of each plot. Nine transects of 50 meters were placed and vegetation cover, density of two dominant species (viz. Astragalus squarosus & Convolvolus hamadae) as well as the total vegetation cover was recorded. Moreover, 220 plants were selected and examined for their dry and green matter. Four soil profiles in each plot were sampled at the depths of 0-20 and 20-80 cm and the samples were further analyzed for their organic matter content. Data analysis was performed using the independent t-test which showed no difference between the treatment and control plots for their total vegetation and species cover. Even though the density of As sq. was lower in the treatment plot of all plants especially As sq, were in good condition and enjoying considerable volumes. While the situation for plants in the control plot were harsh where most plants were drying. The current status in the treatment plot has resulted in a significant rise in the level of organic matter at the depth of 20-80 cm in the mulched areas.
Soil carbon sequestration and storage is one of the important methods to reduce the atmospheric carbon dioxide and mitigating climate change effects. Therefore, with identification of the effective factors on carbon storage can be helpful... more
Soil carbon sequestration and storage is one of the important methods to reduce the atmospheric carbon dioxide and mitigating climate change effects. Therefore, with identification of the effective factors on carbon storage can be helpful to improve soil fertility and environmental protection. Therefore, this study was conducted to investigate the effects of some soil physical factors on soil organic carbon (SOC) storage content in drylands of Sarfiroozabad watershed, Kermanshah province, Iran. So, the watershed was separated into homogeneous zones and soil sampling was performed using a randomized systematic method in the units. The samples were transported to the laboratory and texture, TNV%, gravel% and organic carbon were analyzed to determine the SOC storage. Then, using stepwise regression, cluster and factor analysis, the effective factors on carbon storage were studied. The results of cluster analysis showed three variables such as TNV%, Silt% and SP%, are effective on SOC storage and the regression model with this three variables can predict 33 percent of the soil carbon storage variability with a correlation coefficient of 0.574. Also, cluster analysis to predict the effects of physical factors on carbon storage is important with EF= 0.32. Therefore, it was proven that the soil factors are more effective than climate and topography factors to predict SOC storage. It shows that improving the soil conditions and correct management, to keep soil carbon stocks should be given more attention.
In this study, IMDPA model was used to assess desertification phenomena regarding the importance of agriculture in Mehran plain. Climatic and hydrologic criteria were selected to consider over two periods 2002-2007 and 2008-2012. Two... more
In this study, IMDPA model was used to assess desertification phenomena regarding the importance of agriculture in Mehran plain. Climatic and hydrologic criteria were selected to consider over two periods 2002-2007 and 2008-2012. Two climatic indices (Precipitation index and SPI) and three hydrologic indices (Groundwater level depletion, EC and TDS) were chosen to quantify climatic and hydrologic criteria, with which desertification intensity was calculated and classified for mapping by Arc GIS 9.03. Desertification intensity was classified in four classes including negligible and low, medium, high and very high. According to the results, among studied indices, SPI with the values of 2.45 and 2.78 and the groundwater level depletion with the values of 3.68 and 3.97 were the most effective factors. The results of analysis indicated that drought, decreased precipitation and groundwater level depletion cause an increase in desertification in Mehran Plain.
Growth of human population and increase in using of fossil fuel, cause to increase of greenhouse gases concentration such as atmospheric carbon dioxide over recent decades. In this study, the role of Atriplex canescens in carbon... more
Growth of human population and increase in using of fossil fuel, cause to increase of greenhouse gases concentration such as atmospheric carbon dioxide over recent decades. In this study, the role of Atriplex canescens in carbon sequestration of experimental rangeland station of Nodehak in Qazvin province was investigated. The main treatment applied in a split plot design using the randomized completely blocks including two densities of 2×2 m and 4×4 m. In each treatment, four pruning heights consisting of without pruning (control treatment), completely pruning, pruning in 20 cm and 40 cm above ground. The carbon amount was measured for above and underground biomass and pruning heights, separately. The results showed that mean carbon amount in above and underground biomass per area unit in 2×2 m treatment is significantly higher than 4×4 m treatment. In 2×2 m spacing, the total carbon amount of total biomass (2370 kg/ha) was twice as much amount as 4×4 m treatment. No significant difference was observed in total sequestrated carbon in plant spacing and pruning height treatment. Mean total carbon sequestration per hectare was 59.16 and 59.81 ton in 2×2 m and 4×4 m treatments, respectively. The results suggest that good management practices in rangelands result in increased carbon storage and sequestration of 59626.6 kg/ha.
Water resources management especially for groundwater resources is a very important task in arid and semi-arid regions. Over last decades, because of various natural and anthropogenic factors, critical condition and declined groundwater... more
Water resources management especially for groundwater resources is a very important task in arid and semi-arid regions. Over last decades, because of various natural and anthropogenic factors, critical condition and declined groundwater level have been reported in most regions of the country. With regard to importance of this issue variation pattern of groundwater level in Garmsar plain was assessed using the best geostatistics estimator method over 2002-2011 period. Among the various interpolation methods including Kriging and inverse distance weighting (IDW) with power 1-3, Kriging method was determined as the best interpolation method based on RMSE criterion. Results showed that spatial zoning maps of groundwater level in this period indicates intense depletion of groundwater level in the northwest of the region. Results also show that the average level of groundwater in the whole plain has decreased 3.5 m because of decreased rainfall and over-pumping of groundwater for agricultural uses in the period.
The ancient area of Rey on the central plateau of Iran is a valuable site for archeological sequences in a natural plain. It has valuable natural resources, and history and archeology specialists along with the native and non-native... more
The ancient area of Rey on the central plateau of Iran is a valuable site for archeological sequences in a natural plain. It has valuable natural resources, and history and archeology specialists along with the native and non-native tourists, has given attention to this site. The archeological -natural environment of the fire temple of Rey or the archeological Tappeh Mil of Varamin, located 12 kilometers southeast of Rey, on a high hill beside the historical Ghal’ e No Village, is one of the natural- archeological sites of the region. In this research, through specialized processing of ETM and Quickbird satellite data, in large and small scale and in different study layers, the ecologic structure, landscape features of the determined study region, was studied and the most prominent features of the given natural- archeological structure and the relations and interactions among them were specified in the framework of cultural landscape. Also, keeping in consideration the dynamic ecological structure and the aesthetical features of this area with its environment in integrated conservation approach, the buffer zone of the cultural landscape and the preservative precincts of the natural- archeological environment of Tappeh Mil have been determined. Based on the above-mentioned studies and the features of the landscape, environmental planning and design strategies of the Tappeh Mil have been determined.
One of the methods for water resources development to meet water supply requirements, is the use of treated urban wastewater. In this paper, the feasibility of use of refined urban wastewater of Sabzevar was evaluated. This study was... more
One of the methods for water resources development to meet water supply requirements, is the use of treated urban wastewater. In this paper, the feasibility of use of refined urban wastewater of Sabzevar was evaluated. This study was implemented in Dorok desert land located in southwest of Sabzevar over three year( 2009- 2011). In order to meet this general objective, the complete randomized block design with three treatments (Haloxylon, Atriplex and Nitraria schober) in 9 replicates per treatment was selected. To evaluate the quality of the effluent, the samples were taken from sewage wastewater treatment plant of Sabzevar and entering water to the collecting reservoir. The samples were analyzed in the laboratory to study the major contaminants based on environmental standards for sewage in Iran. The results of this part of study showed that all evaluated parameters are suitable for irrigation, except for two parameters of Dissolve Oxygen (it was solved by mixing it with seasonal flooding) and coliforms count in the effluent. The results in terms of classifying the quality of wastewater for agriculture and irrigation by Wilcox diagram, showed the class C3-S1, which means relatively suitable class. To evaluate the second objective, areas planted were divided into three sections and each section is divided into three parts (9 repetitions). For evaluation of plant density (percentage of plant), 120m transects was used and the results showed that on average, 67 percent of Haloxylon, 74.3 percent of Atriplex and 90.3% of Nitraria schober have survived. The results are indicators of match effects which are at 1% level meaningful.
One of the striking aspects in the world is the phenomena of desertification and degradation of natural resources and international efforts has been considered over the last decades to combat and prevent this phenomenon. The most... more
One of the striking aspects in the world is the phenomena of desertification and degradation of natural resources and international efforts has been considered over the last decades to combat and prevent this phenomenon. The most important cases of these measures are the United Nations Convention to Combat Desertification and adaptation to drought effects. The Convention introduced some measures on desertification monitoring and assessment to the member countries. The aim of this study was to assess desertification model IMDPA is Yazd-Ardakan plain. During this study due to time constraints and literature, some indicators of water and climate were selected for each condition of the region. Indicators to measure were groundwater levels depletion and electrical conductivity for water criterion; and drought, aridity and continuous droughts period for the climate criterion. First, the geometric mean of indicators and the criteria of desertification was calculated and based on the quantitative indicators and benchmarks desertification status was classified in 5 classes including non-significant, low, moderate, severe and very severe, and desertification condition map were drawn using GIS in the studied period. According to the results and the numerical measured values, groundwater level depletion with the value of 3.84 is the most effective indicator while continuous drought period with the numerical value of 0.53 showed to have the lowest impact on desertification of the region. According to the analysis, the numerical value of the water criterion is 3.44 is the most effective factor which shows severe condition of desertification in the region.
Land cover and land use change occurs during the time due to human activities. Identification and detection of these changes can help planners and managers to recognize the effective factors which cause the changes, and use them at... more
Land cover and land use change occurs during the time due to human activities. Identification and detection of these changes can help planners and managers to recognize the effective factors which cause the changes, and use them at different levels of planning. Studying the rate of resources changes and destruction, and prediction and feasibility study of these changes in future years may play a key role in planning and optimal use of resources and controlling undesirable changes in the future. There are various methods for predicting land use and land cover changes, among them the Markov Chain model can be pointed out. In this study, by using the Landsat satellite data of TM (1995) and ETM+ (2000 and 2007) sensors, complementary data of the study area and Markov Chain model the changes occurred in land use and land cover over the past 22 years in Doviraj region of Ilam province are investigated. After performing required corrections on the satellite images and field visits, different land use classes were defined, the training samples were selected and the accuracy of obtained results was evaluated using Kappa coefficient. The results indicate the decreasing trend of forest cover and average rangeland areas of the region (i.e. 2.9 and 17.07 percent , respectively) and increasing trend of poor rangelands, agricultural lands, residential areas and barren land uses (9.17, 2.96, 0.4 and 7.44 percent, correspondingly) which represent total destruction in the region and replacement of weaker land uses. Finally, using Markov Chain model, the status of land use classes in the next 14 years (2021) has been predicted. The results from changes prediction matrix based on the maps of 2000 and 2007 showed that in the time period of 2007-2021 it is probable that 62% of forest lands, 38% of average rangelands, 64% of poor rangelands, 72% of agricultural lands, 69% of residential areas and 76% of barren lands remain unchanged. The average rangelands are of the highest stability and on the other hand poor rangelands have the lowest stability. The calibrated land use maps by Markov Chain model can be employed as an alarming system about the effects and consequences of future land use changes.
Numerous indicators for drought monitoring in different time scales have been used for monthly and yearly data series. One of the limitations of conventional indicators such as the Standardized Precipitation Index (SPI) is no attention to... more
Numerous indicators for drought monitoring in different time scales have been used for monthly and yearly data series. One of the limitations of conventional indicators such as the Standardized Precipitation Index (SPI) is no attention to the water balance based on the amount of evapotranspiration. The Standardized Precipitation Evapotranspiration Index (SPEI) which is based on precipitation and potential evapotranspiration incorporates the water balance in the drought index. The purpose of this study is investigating the intensity, duration and frequency of the meteorological droughts in Tehran province using SPI and SPEI in order to determine the relationship between these indices for optimized management of water resources. In this study, the data of monthly precipitation and average monthly temperature for a period of 30 years (1978-2008) in six gauging stations in Tehran province were used. The results indicated that there is a significant correlation between SPI and SPEI while SPEI show a quick response to the meteorological drought.
Wind erosion and sedimentation include detachment, transportation and deposition of soil particles by wind. To increase stability of soil surface and for soil conservation against wind erosion, artificial covers can be used, along with... more
Wind erosion and sedimentation include detachment, transportation and deposition of soil particles by wind. To increase stability of soil surface and for soil conservation against wind erosion, artificial covers can be used, along with vegetation cover. Among artificial covers, one can use industrial residuals. Steel slag is a by-product of iron and steel industries which is produced in massive amount in Isfahan and contains valuable combinations and material. The study area is Harand plain in east of Isfahan which is one of the most critical erosion sites in Isfahan province. The experiment treatments included thicknesses at 2 levels (1 & 2 layers), cover percentage at 4 levels (25, 50, 75 and 100 percent), graining at 3 diameter levels (15-30, 30-45& 45-60 mm), wind velocity at 7 levels and their reciprocal effects. Test took place with 4 factorial replications and by completely random design, and then data got analyzed with Duncan & ANOVA tests in SPSS 15 and Excel. The results showed that steel slag increased the surface coarseness and therefore can control the erosion. Increasing area cover, size and graining of mulch, decline the soil loss. However there was no significant difference between the numbers of applied layers. It is citable that simultaneous increase in area percentage, size and diameter of slag decline the soil loss as well. According to the results, slag mulch can be used for erodible sediments control with 50% density, 30-45 mm graining and in one layer.
Kashan Erg is one of the most important sand sea complexes in Iran. The Current research tried to determine the homogeneity of Kashan Erg through multivariate data analysis. Data was extracted by interpretation of aerial photographs,... more
Kashan Erg is one of the most important sand sea complexes in Iran. The Current research tried to determine the homogeneity of Kashan Erg through multivariate data analysis. Data was extracted by interpretation of aerial photographs, Google earth, field observations and morphologic map of the study area. Moreover, different statistical variables of aeolian sediment samples were conducted in different sand dunes. The granulometric parameters were also calculated based on the dry sieve analysis while mean diameter, sorting, skewness, kurtosis, d10, and d90 indices were calculated using GRADISTAT software. Wilks’ lambda and canonic coefficients results indicated that, among granulomtric data, skewness and kurtosis could distinguish different sand dunes types (accuracy of 57%). According to the above mentioned indices, the classification was performed using Hierarchical Cluster analysis. The results showed that the stabilized dunes were located in the separate group which related to the effect of vegetation establishment and ability of wind in transporting of fine particles of these areas. Also, bivariate plots used for evaluating the homogeneity of the sand dunes which indicated d10 and d90 parameters as a discriminant factors for graphical and visually separation, but not statistically. Findings revealed that by using quantitative multivariate methods for sand dunes classification, less experimental insights can affect the results.
Assessment of natural resources projects is one of the most basic problems that are done to program the upcoming applied plans and management of these fields in different countries. In this study, the assessment of watershed operation in... more
Assessment of natural resources projects is one of the most basic problems that are done to program the upcoming applied plans and management of these fields in different countries. In this study, the assessment of watershed operation in Tochal watershed basin was carried out through some primary studies and then integrating them together. In addition to watershed operation, was studied biological operation in study region. According to pizometric statistics wells in studied area, was appraised to improvement of water resources in before and after of Implementation of operation. At first, the efficiency percentage was determined for each of the applied structures by evaluating the condition of structures through field study. The aim of the execution of biological operation has been increase of the rate of permeability in construction operation, in addition of consolidation of sediment in area. The result of reviews show, the efficiency percentage of gabion, stone – cement, and the other structures were 75, 66, and 14. 8 respectively. In biological operation, some activities are offered, for example, nothing Spades, working Plant, seeding, drilling and protection. that among of this the proposed operation is executed: 10 hectare for working plant,1000 hectare for drilling, 700 hectare for seeding and 500 hectare for protection. The biological operation has just done for erosion controlling and soil conservation the volume of the precipitation behind the structures was calculated as 49775. 3 m3 and most of the structure capacity to control precipitation was for sediment control. Also with considering climatic parameters, SPI index statistical period was drawn. With drawing underground water hydrograph, the performance of biological and structural operation was considered in increasing of underground water level. The average of discharge has increased 30.36 liter/second.
Desertification consists of land degradation in arid, semi-arid and dry sub-humid areas induced by climate change and human activities. For evaluation and mapping of desertification many research have been conducted leading to regional... more
Desertification consists of land degradation in arid, semi-arid and dry sub-humid areas induced by climate change and
human activities. For evaluation and mapping of desertification many research have been conducted leading to regional
and local models. In this research, among different existing methods, IMDPA model was selected and desertification
intensity of Garmsar plain was evaluated based on 2 criteria and 6 indices including: climate (precipitation, drought and
aridity index) and water (groundwater table depletion, electrical conductivity, sodium absorption ratio) over four
periods; 1995-1997, 1997-2003, 2003-2009 and 2010-2012. Each criterion was assessed based on the selected indices
resulted in qualitative mapping of each criterion based on geometric average of the indices. Finally, desertification map
of the region was extracted using geometric average of criteria for each period. Thematic databases, with a 1:50000
scale resolutions were integrated and elaborated in ArcGIS9.3. The results showed that during the periods, four indices
including groundwater table depletion, electrical conductivity, aridity index and precipitation index have the most
significant effects on desertification with the values of 3.81, 3.17, 3.11 and 3.09, respectively. Also two indices
including Sodium absorption ratio and drought have the least effect on desertification with the values of 1.17, 1.63 of
the Plain, respectively. Also, analysis of desertification criteria in Garmsar region showed that among studied criteria,
water criteria have had the most effect on land degradation and desertification since 1994.
human activities. For evaluation and mapping of desertification many research have been conducted leading to regional
and local models. In this research, among different existing methods, IMDPA model was selected and desertification
intensity of Garmsar plain was evaluated based on 2 criteria and 6 indices including: climate (precipitation, drought and
aridity index) and water (groundwater table depletion, electrical conductivity, sodium absorption ratio) over four
periods; 1995-1997, 1997-2003, 2003-2009 and 2010-2012. Each criterion was assessed based on the selected indices
resulted in qualitative mapping of each criterion based on geometric average of the indices. Finally, desertification map
of the region was extracted using geometric average of criteria for each period. Thematic databases, with a 1:50000
scale resolutions were integrated and elaborated in ArcGIS9.3. The results showed that during the periods, four indices
including groundwater table depletion, electrical conductivity, aridity index and precipitation index have the most
significant effects on desertification with the values of 3.81, 3.17, 3.11 and 3.09, respectively. Also two indices
including Sodium absorption ratio and drought have the least effect on desertification with the values of 1.17, 1.63 of
the Plain, respectively. Also, analysis of desertification criteria in Garmsar region showed that among studied criteria,
water criteria have had the most effect on land degradation and desertification since 1994.
This study deal with investigation of the effect factors on dryness of planted Haloxylon considering the importance of its role in soil stabilization especially mobile sands and also enormous costs were done for biological developments.... more
This study deal with investigation of the effect factors on dryness of planted Haloxylon considering the importance of its role in soil stabilization especially mobile sands and also enormous costs were done for biological developments. For this research one peer site from planted Haloxylon area, 5 vigor Haloxylon sets, 5 semi-vigor Haloxylon set and 5 wilted Haloxylon sets were chosen based on plants appearance in the study site. Haloxylon shrubs were cut from the ground and the leaves were separated, then ratio of leaf to stem, therefore this ratio become an indicator of given vegetation. From 15 total selected Haloxylon sets, 15 samples of shots and 15 samples of roots were taken for conducting chemical tests and value of sodium, calcium, magnesium, potassium, and phosphorus were determined in the laboratory based on the standard methods. The effects of measured factors on plant vitality index were evaluated by univariate analysis of variance. The results suggest that with regards to the important role of phosphorus, potassium, calcium and magnesium in plants, their shortage in shoots reduce vigor index.
This study investigated the changes of proline, soluble sugar, Na, K and N in Atriplex lentiformis, Halostachys belangeriana and Tamarix rammossma over two seasons (winter and summer) in the field conditions. Five plants all in the same... more
This study investigated the changes of proline, soluble sugar, Na, K and N in Atriplex lentiformis, Halostachys belangeriana and Tamarix rammossma over two seasons (winter and summer) in the field conditions. Five plants all in the same sizes and forms from each species in Chahafzal area of Yazd province were collected and the above mentioned indices were measured. Results showed that the highest amount of proline and sugar were found in Halostachys belangeriana and Atriplex lentiformis, respectively. Meanwhile, the amount of proline in all plant over summer was significantly more than winter. The amount of proline in summer in Halostchys belengeriana was also equal to 3.2 mg/gfw. In Atriplex lentiformis and Tamarix rammossma, the amount of sugar in summer was significantly more than winter. The highest amount of sugar was found in Atriplex in summer measurement which was equal to 6.8 mg/gdw. In contrast to two mentioned species, sugar content of Halostchys belengeriana in winter was more than summer. The amount of N and K were not significant in any of the species. Na in Halostchys belengeriana was significantly high compared with two other species. It is concluded that these halophyte species tolerate with different mechanisms to cope with salinity and drought stresses.
The purpose of this study was to evaluate the success rate of planting project. Also reviews combating desertification in this region by the Project. First, plant characteristics including canopy cover and vegetation density were measured... more
The purpose of this study was to evaluate the success rate of planting project. Also reviews combating desertification in this region by the Project. First, plant characteristics including canopy cover and vegetation density were measured by transect of 100m and plots of 225m2 (15×15), respectively. Also physical (soil texture) and chemical properties of soil samples including salinity and acidity at three depths of 0-30, 30-60 and 60-90cm (roots evelopment zone) were measured. A region as a flood spreading area including three phases, two phases of Atriplex and one phase of Haloxylon was selected. Also, another region was considered as the control area. The results were compared by Duncan's test according to Completely Randomized Block design. The results of physical and chemical properties of the soil samples showed that the electrical conductivity and pH have decreased in the most samples. These changes were significant at the 5% level. Soil texture and sand increased but clay has decreased in the depth of 0-30cm, therefore soil structure has improved. The results of plant characteristics showed that water spreading has positive effects on establishment and natural regeneration of the planted spices (15.75 percent increase) and these changes are significant at the 5% level. Based on canopy cover and vegetation density results, there are no significant differences between Atriplex and Haloxylon; but the establishment of endemic species has been more successful in Haloxylon phase.
Ground water has been important water source within all centuries. Due to this important, necessity is aware of how spatial and temporal changes in these variables that in many areas is important. Exploitation of the Aquifer Aspas and... more
Ground water has been important water source within all centuries. Due to this important, necessity is aware of how spatial and temporal changes in these variables that in many areas is important. Exploitation of the Aquifer Aspas and also continuous drought in recent years has caused a dramatic reduction in groundwater levels. In the past, the level of groundwater at a depth of 7-5 meters from ground level, but already because of excessive use numerous wells has reached to a depth of 60-50 meters. As a result, management factors are important in this the plains. The aim of this study, has been investigated the relationship between changes in the water table aquifer and salinity during the period of (2002-2010). For this purpose, were used the meteorological data (the average annual precipitation for the precipitation process), Groundwater monthly quality data (including electrical conductivity to investigation salinity), quantitative data Groundwater (includes monthly Groundwater level of observation wells of plains to show status of groundwater fluctuations and the unit hydrograph the plains). unit hydrographs shows that during the period of (2002-2010), groundwater level declined and the average of drop has been 0.7 meters per year, On the other hand can be seen an inverse relationship between the water table and salinity. Comparing of changes in electrical conductivity and groundwater level in the aquifer showed that Salinity is higher in areas where the water table is lower.
Deserts have been described in different aspects of the natural environment. In this article, we try to determine desert territory using soil properties. Those selected soil properties which identify desert soil criterion were: soil... more
Deserts have been described in different aspects of the natural environment. In this article, we try to determine desert territory using soil properties. Those selected soil properties which identify desert soil criterion were: soil salinity (EC), soil reaction (pH), gypsum, calcareous, SAR, organic matter, soil texture and clay pan. The soil properties were used as limiting factor for plant growth. Using available soil information, digital maps in GIS for every province were prepared. After their overlying, we prepared a map for Iran desert areas. The results showed that 544320 km2 of Iran known as a desert which formed under soil properties conditions. In these areas the soil EC is more than 8 dS/m, pH more than 8.5, SAR greater than 12; genetic and biological soil horizons have no significant distinction. The saline soil puffy, desert pavement, clay pan and active and non active sand dunes are also visible in the desert. Also the results showed that greater Khorasan and Markazi provinces have the highest and lowest soil-desert areas of 137665 and 1932 km2, respectively.
Land cover is defined as a physical and biological cover of the earth’s surface that contains water, vegetation and bare soil. Limiting factors in arid areas such as water shortage and soil salinity are important factors to study the... more
Land cover is defined as a physical and biological cover of the earth’s surface that contains water, vegetation and bare soil. Limiting factors in arid areas such as water shortage and soil salinity are important factors to study the occurred changes in land cover. Due to the large expanse of land, change detection by the traditional methods is not sufficient and efficient; therefore, using of new methods such as remote sensing technology is necessary and vital. The overall aim of this study was to assess changes in land cover in arid lands of Marvast plain, located in south of Yazd. In this study, ASTER (Terra) data for summer month of July for years of 2003 and 2010 as well as ETM+ data (Landsat) for July 2002 and 2010 was used. In the first step, after pre-processing operations such as geometric correction, land cover maps of the study area were classified into 5 classes (agricultural land, rangeland, bare land, desert and wetland) using Maximum Likelihood method in both satellite types. Then, taking ground truth data, the classified maps accuracy were assessed by calculating the Kappa coefficient and overall accuracy. The results of ETM+ classification show that the areas of agricultural land and wetland were increased and decreased, respectively in time span of 2002-2010. The same changes were also observed in change classification maps of ASTER for the period of 2003-2010. In this time period, the area of wetland is decreased and changed into desert area. In addition, rangeland area has reduced and changed into agricultural land. The results show that produced maps of both sensors have accuracy of above 85% which reflects high performance of both images in land cover change analysis. In spite of the fact that ASTER data is a little more accurate, results of using Landsat data which has more accessibility and lower cost, for change detection analysis is also acceptable and valuable.
In recent years, the idea of nebkhas as a degradation index changed to signs of adaption and stability in desert conditions. Plants growth condition is very restricted in desert biomes, but nebkhas ecologically provide a better condition... more
In recent years, the idea of nebkhas as a degradation index changed to signs of adaption and stability in desert conditions. Plants growth condition is very restricted in desert biomes, but nebkhas ecologically provide a better condition for some plants to grow. Nebkhas also change physical and chemical properties of the soil and also water balance conditions. In this study infiltration rate was compared between nebkhas formed by Ephedra strobilacea and Tamarix ramosissima and soil between nebkhas in Abarkouh area located in Yazd province. In addition, there are many hydrological models that use Green-Ampt or Horton equations for forecasting surface runoff. So this study also evaluated the efficiency of Green-Ampt or Horton equations. At the first, the locations of each nebkhas were recognized and soil of nebkhas and the soil between nebkhas were sampled. Soil samples were then delivered to the laboratory and main physicochemical characteristics of all samples were measured. Infiltration rate was measured by double ring between nebkhas (bare) and in the nebkhas of the two species. Horton and Green-Ampt constants were also calculated. Infiltration models efficiency were analyzed by calculation of NashSutcliffe coefficient and RMSE-Standard Deviation of Observation (RSR). Final permeability was measured at about 24 cm/hr for Ephedra strobilacea and Tamarix ramosissima nebkhas. Final permeability for between nebkhas (bare) of Tamarix ramosissima and Ephedra strobilacea were measured 3.6 and 7 cm/hr, respectively. Final permeability for Ephedra strobilacea and Tamarix ramosissima nebkhas was 6.7 and 3.4 times more than between nebkhas. It is concluded that nebkha play an important role in water infiltration and water resources in desert areas. Nash Sutcliffe ranges showed Green-Ampt and Horton models are in acceptable levels of performance for predicting infiltration rate of Tamarix ramosissima and Ephedra strobilacea nebkhas. However, the models show less accuracy for soil between nebkhas (bare), because of soil stratifying. The cause of these differences is that Aeolian materials of nebkhas sorted by wind show homogenous texture compared with the layered soil of between nebkhas. Horton and Green -Ampt models assumptions have conformity with homogenous soils.
A major part of ground water resources is used for irrigation of farm lands. So appropriate management should be applied considered for application of these limited resources. In this research, 30 wells were selected over three time steps... more
A major part of ground water resources is used for irrigation of farm lands. So appropriate management should be applied considered for application of these limited resources. In this research, 30 wells were selected over three time steps 1998, 2002 and 2009 in Mosafer Abad plain of Hormozgan province and some chemical properties such as Na, Cl, EC, pH, TDS, TH and SAR were analysed for zoning at the mentioned time steps. The purpose of this study is to determine the most appropriate interpolation method to analyze the spatial variability of landscape characteristics of groundwater quality of Mosafer Abad plain using Kriging, IDW (Inverse Distance Weighting and RBF (Radial Basis Functions) methods. Result shows that Kriging method with RMSE values lower than other methods is more acceptable approach for the study area. Meanwhile, the results revealed that average depletion of water table levels in at 1998, 2002 and 2009 are -0.152, 0.629 and -0.384 meter, respectively. This Represents a decreasing trend in groundwater level in wells and indicates a meaningful warning for more attention to ground water resources in Mosafer Abad plain.