عنوان مقاله [English]
In traditional irrigation systems, inappropriate management of water allocation may lead to poor performance of the irrigation district, an increase in water losses, and a reduction in crop water productivity (CWP). Using optimization methods and nonlinear models along with the geographical information system (GIS) can improve the management of an irrigation district under uncertain condition. The objective of this study is to investigate the optimal water allocation and reasons for the CWP reduction in irrigation distribution district. To do so, in the first stage, those sites of water distribution district with the highest effects on CWP variability were identified. Then, the CWP was increased, later. For this purpose, fuzzy programming models and the possibility theory are used to prepare a water allocation plan for the irrigation system of Sistan Dam. The results show that the highest CWP of irrigation district for wheat fields is 0.45 kg/m3, which exist at the sites by the range of discharge losses in 360 to 400 L/m/hr. The analysis of these critical spots shows that the CWP values do not necessarily depend on crop productivity but they may depend on the management factors of irrigation district and the cultivated areas. Therefore, the spots with an optimized CWP could be considered as suitable patterns for increasing the management efficiency.