The investigation of water uniformity distibution and irrigation efficiency on some irrigate farms in lorestan province

This study was conducted to evaluate the present management of border irrigation system in wheat, sugar beet, alfalfa and bean farms that irrigated by this system in Lorestan province. Experimental farms included 5 wheat farms, 4 alfalfa farms, 4 bean farms and 3 sugar-beet farms in Khorramabad, Dorod, Aleshtar and Chaghalvandi cities. The experiments were conducted in traditional borders with prevalent dimensions, slopes, and management practice. The relationship between management allowable deficit (MAD), soil moisture deficit before irrigation (SMD) and infiltrated depth indicated that in most cases deficit irrigation and or stress irrigation had been made. This is caused to increase water application and storage efficiencies, but in most cases irrigation sufficiency was not made. This is resulted from imbalance between system fractions and depletion in initial soil moisture. Range of water application, storage efficiency, deficit/excess efficiency, deep percolation, tail water efficiencies in the farms under experiment, was measured from 10.5 to 95.5, 21.6 to 100, 9.3 to 100, 0.6 to 83.5 and zero to 42.9 percent, consequently. Irrigation curves implicated the effects of initial soil moisture, slope gradient, and border dimentions on entrance flow and distribution uniformity of water. Also irrigation management changes caused signifacant effects, for example each entrance rate created specific curves. Uniformity of water distribution indexes were low and caused water loses by deep percolation. Inspite of water losses due to deep perculation and runoff, dificit irrigation was observed in 82 percents of farms. Results indicated that irrigation management was inefficent. By the way due to: lake of farmers knowledge about soil moisture condition and correct time irrigation, inefficient and traditional exploitation and owner system of land and water resource, weak irrigation scheduling as well as imbalance between irrigation system properties which lead to water losses and reduced irrigation efficiency.