ON FIELD ASSESSMENT OF TRADITIONAL MANAGEMENT EFFICIENCY IN BORDER IRRIGATION SYSTEM IN LORESTAN PROVINCE, WEST OF IRAN EVALUATION A LA PARCELLE DE L'EFFICIENCE DE GESTION TRADITIONNELLE DU SYSTEME D'IRRIGATION PAR PLANCHES DANS LA PROVINCE DU LORESTAN A L'OUEST DE L'IRAN

Irrigation efficiency reflects how good or bad the water resources are being used for irrigation. Traditional border irrigation system is prevalent system in about 80% of irrigated lands in west areas of Iran. A study was conducted to evaluate the present management efficacy of border irrigation system across the field in 16 wheat, sugar beet, alfalfa, and bean farms in Lorestan province, and west of Iran. Results indicated that in most cases deficit irrigation were used. This increased water application and storage efficiencies, but in most cases, irrigation sufficiency were not achieved. This is resulted from imbalance between system fractions and depletion in initial soil moisture. Range of application efficiency, 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 0 to 42.9 per cent, respectively. Uniformity of water distribution indices were low and caused huge water loses (about 30-60% of the water that entered the border) occurred by deep percolation, especially along the first half of border length. Lack of farmers’ knowledge about soil moisture condition and accurate irrigation time, traditional system layout, weak irrigation scheduling as well as imbalance between irrigation system properties lead to water losses and reduced irrigation efficiency. Practical solutions to enhance irrigation management efficiency are to adjust geometric features of border based on amount of water entrance, regulate cut-off time as well as to determine appropriate irrigation time based on pre-irrigation soil moisture.