Comparison of Wind Drift and Evaporation Losses and Performance Evaluation Indices in Three Sprinkler Irrigation Systems with Emphasis on Water Resource Sustainability (Case Study: Poldasht County)

Introduction
Water is the most critical and limiting input for agricultural production in Iran, where severe water scarcity poses substantial threats to food security and sustainable agriculture. Factors such as population growth, prolonged droughts, and the over-extraction of water resources have intensified the water crises across the country, leading to adverse social and economic consequences. Given that over 90% of the country’s renewable water resources are consumed in the agriculture sector, optimizing irrigation efficiency through the adoption of modern irrigation technologies has become an urgent necessity. Efficient water management not only conserves scarce resources but also enhances crop yield and mitigates environmental impacts. In this context, the present study was designed to comprehensively evaluate the performance of three sprinkler irrigation systems, namely the conventiona gun sprinklers, the spray boom, and a farmer-modified water distribution system, under field conditions along the Aras River in Poldasht, West Azerbaijan, Iran. The objective was to provide a detailed comparison of these systems in terms of water distribution uniformity, Christiansen’s uniformity coefficient (CU), application efficiency (Ea), and losses due to evaporation and wind drift. By systematically assessing these performance indicators, the research aimed to identify the most effective and sustainable irrigation method for semi-arid agricultural regions, where water scarcity and environmental challenges render efficient irrigation practices critical for crop productivity and long-term resource management. Furthermore, the study explored the potential of low-cost, site-specific modifications implemented in the farmer-designed systems to improve water use efficiency and reduce operational losses. The findings are intended to offer practical insights for optimizing irrigation strategies in similar agro-climatic zones.
Materials and Methods
The study was conducted on 59 hectares of privately owned farmland characterized by sandy loam soil, located in a semi-arid cold climate in Poldasht, West Azerbaijan, Iran. The site is situated along the Aras River at an elevation of 874 meters above sea level. Field experiments were carried out during July, August, and September 2018 to evaluate the performance of three sprinkler irrigation systems. The assessment focused on key performance indicators including distribution uniformity (DU), Christiansen’s uniformity coefficient (CU), application efficiency (Ea), and losses due to evaporation and wind drift. To quantify water distribution, catch cans were strategically placed in multiple rows across the irrigation strips, and the overlapping effects of adjacent irrigation lines were incorporated into the calculations to accurately determine the actual water depth received at each location. Soil physical and chemical properties, including texture, bulk density, infiltration rate, pH, and electrical conductivity, were analyzed to understand their influence on water movement and retention. Water quality parameters were also measured to ensure suitability for irrigation. Additionally, the farmer-designed system was adjusted and optimized under field conditions, Modifications included alterations to lateral pipes and nozzle configurations aimed at improving water application uniformity and reducing operational losses.
Results and Discussion
The results of the field evaluation revealed significant differences in performance among the three sprinkler irrigation systems. The spray boom system demonstrated the highest efficiency and uniformity, with average Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), and application efficiency (Ea) of 94.7%, 91.1%, and 85.8%, respectively, indicating excellent irrigation performance. In contrast, the gun sprinkler system exhibited the lowest performance, with CU = 68.7%, DU = 64.9%, and Ea =67.6%, and recorded the highest evaporation and wind drift losses, averaging 22.7%. These performance variations were largely attributed to factors such as spray height, droplet size, and wind conditions, which significantly influenced water distribution and losses under field conditions. The farmer- modified water distribution system, which incorporated on-farm modifications including direct water application via lateral pipes and te removal of standard nozzles, achieved an acceptable performance level with CU = 89.9%, DU = 85.7%, and Ea = 94.2%. Evaporation and wind losses were negligible in this system due to the reduced exposure of water droplets to the atmosphere. The data further indicated that overlapping of irrigation lines played a critical role in achieving more uniform water distribution, particularly for the spray boom and gun sprinkler systems. Overall, the findings underscore the importance of system design, operational adjustments, and site-specific adaptations in achieving high irrigation efficiency and minimizing water losses.
Conclusion
The study demonstrated that the type of sprinkler irrigation system, along with its design and operational practices, has a decisive influence on water distribution uniformity, application efficiency, and losses due to evaporation and wind drift. Among the three systems evaluated, the spray boom system exhibited superior performance, achieving excellent uniformity and efficiency, whereas the gun sprinkler system showed the poorest results, primarily due to higher droplet height and susceptibility to wind. The farmer-designed water distribution system, despite being developed empirically, performed effectively, underscoring the potential of low-cost, site-specific modifications to enhance irrigation efficiency. These findings indicate that adopting spray boom systems or modified on-farm water distribution methods can substantially improve irrigation efficiency, reduce water losses, and promote sustainable water management in semi-arid and windy regions. Moreover, periodic evaluation of system performance and installation of proper filtration to prevent nozzle clogging are essential for maintaining long-term efficiency and reliability. Overall, this study offers practical insights for optimizing sprinkler irrigation practices and encourages the adoption of cost-effective, farmer-adapted solutions in water-scarce regions.