Assessment of the Total Irrigation Efficiency and Real Hydro Module using Water Balance Method (Case Study Nazlouchai Plain of Urmia)

This study was carried out in 2012 to determine the total irrigation efficiency and real hydro module of Nazlouchai plain in Urmia, using water balance method. In addition to field experiments, we used data gathered from previous documents and related analytical conclusions. Field experiments conducted in 14 farmer’s fields. The result showed that water application efficiency varied from 55.4 to 78.8%. Water distribution efficiency varied from 75 to 94% and water conveyance efficiency was 66 to 92%. Total efficiency of traditional network estimated 44% and net water requirement of cropping pattern of the plain based on Penman-Monteith method calculated about 4930 m^3/ha, thus gross water requirement of cropping pattern was 11204 m^3/ha. The traditional irrigation network of Nazlouchai plain, with 29050 hectares of land, is located in the lower part of Nazlouchai basin. Annual water withdrawal from Nazlouchai river estimated about 128 Mm^3 and differential of input – output of the plain groundwater estimated about 13 Mm^3 annually. Water balance of Nazlouchai plain was negative with 29 Mm^3/year shortage. Estimation reveald that water consumption of Nazlouchai plain was 170 Mm^3 and irrigation actual hydro module of the plain 5838 m^3/yr/ha. The results showed that water efficiency of Nazlouchai plain in agricultural activities was about 85%. The results of this study showed that the actual rate of agricultural water consumption was lower than what was declared, based on national efficiency; the figures announced for water productivity in agricultural production should be reviewed too.