Evaluation of Irrigation Efficiency and Distribution Uniformity of Water in Border Irrigation System in Lorestan Province, Iran

This study was conducted to evaluate the present management of border irrigation system in 16 wheat, sugar beet, alfalfa, and bean farms that use traditional border irrigation in Lorestan province. The relationship between management allowed deficit (MAD), soil moisture deficit before irrigation (SMD), and infiltrated depth of water indicated that, in most cases, deficit or stress irrigation were common. This had caused high water application and storage efficiencies, while, in many cases, irrigation was insufficient to meet crop requirement. These findings indicated the imbalance between system fractions and excessive depletion of soil moisture before irrigation. Efficiency of water application, storage, and deficit/excess ranged from 10.5% to 95.5%, 21.6% to 100%, and 9.3% to 100%, respectively, while deep percolation and tail water efficiencies were, respectively, 0.6 to 83.5 and zero to 42.9. Advance and recession curves implicated the effects of initial soil moisture, slope gradient, and border dimensions on entrance flow and distribution uniformity of water. Uniformity of water distribution indexes was low and caused water loses by deep percolation. Results indicated that irrigation management was inefficient. Insufficiency of farmers’ knowledge about soil moisture condition and the correct time of irrigation, inefficient and traditional exploitation and the system of land tenure and shortage of water resources, improper irrigation scheduling, as well as imbalance between irrigation system design and management lead to water losses and reduced irrigation efficiency.