In this research, to save water resources and increasing net income, a linear and nonlinear programming model for optimizing three scenarios including existing cropping pattern, agriculture ministry policies and suggested pattern was used for the irrigation levels of 100%, 90%, 80%, 70%, 60% and 50% in the downstream lands of Doyraj Dehloran reservoir, Ilam province in Iran. Net profit changes for the nonlinear programming model related to the linear model for the ministry of agriculture policies and suggested scenarios decreased 0.86% and 2.83%, respectively at full irrigation and 80% irrigation as the optimal treatment, Increased 3.3% and 5.77%, respectively. Water saving changes from nonlinear programming model compared with linear model at all low irrigation treatment in the suggested scenario was increased with at least 0.8% and 1.55% for 90% low and 60% low irrigation, respectively. Generally, in this research nonlinear programming model relative to the linear model at suggested and agriculture ministry policies scenario related to existing crop pattern had increased both the net profit and water saving.
