In arid and semi-arid regions, limited water and low soil moisture are critical constraints on vegetation development. Effective runoff management is a key strategy for enhancing soil moisture and promoting plant growth. This study evaluated the effects of the semi-circular bund system a surface runoff management technique, on the canopy characteristics of three tree species in the Halvaei region of Minab County, Hormozgan Province, Iran. The research included Prosopis cineraria (L.) Druce, Ziziphus spina-christi (L.) Willd., and Acacia ehrenbergiana Hayne (syn. Vachellia flava (Forssk.) Kyal. & Boatwr.). A factorial randomized complete block design (RCBD) was employed to compare tree growth in a treated area with semi-circular bunds against an untreated control. Measured variables included tree height, major and minor crown diameters, crown volume, and projected area, with data collected from 30 individual trees per species in each replication. Results showed that the water-harvesting treatment significantly affected all measured canopy variables (p < 0.01), except for crown thickness. Trees in the treated area exhibited significantly greater height, crown diameter, canopy surface area, and crown volume than those in the control. No significant differences occurred among positions within the treated area (upstream, midstream, and downstream), suggesting uniform system effects across the site. Species responses varied: Prosopis cineraria attained the greatest height and canopy volume, whereas Ziziphus spina-christi exhibited the largest trunk diameter and canopy area. Both species significantly outperformed Acacia ehrenbergiana, which recorded the lowest values. Overall, this study demonstrates the strong positive effects of the semi-circular bund system on tree growth and underscores the importance of selecting species with high adaptive capacity. These findings provide a solid scientific basis for decision-making in ecosystem restoration and sustainable land management, particularly under increasing drought stress and climate change in water-limited environments.