Assessment of the Effects of Deficit Irrigation and Decrease in Water Allocation on Agricultural Sector Production in Qazvin Province

To be safe from the risks of drought and water crisis in the future, it is necessary to follow the guidelines and rules for proper utilization of limit water resources. In this regard, using deficit irrigation strategies creates a balance between water use and the available resources (rivers, groundwater and dams) and also causes the optimization of water use in agriculture. In this study, in order to assess the effects of deficit irrigation on cropping patterns and farmers’ gross profit in Qazvin province, first, agricultural production functions based on three techniques of full irrigation, 5% deficit irrigation and 10% deficit irrigation were estimated. Then, optimal cropping patterns were determined by using a non-linear programming model in Qazvin province. In the end, the effects of deficit irrigation with irrigation water reduction under scenarios of 10%, 20%, 30% and 40% were investigated on cropping pattern and farmer's gross profit simultaneously. Agricultural production functions were estimated by using Ordinary Least Squares method and Eviews software. Also, the non-linear programming model in GAMS software was solved. Results of the estimation of production functions showed that 5% deficit irrigation technique creates a slight decrease in crops yield. But, 10% deficit irrigation technique has negative impact on yield of most crops. The results of non-linear programming model showed that, although simultaneous application of deficit irrigation technique and irrigation water reduction policy reduces the farmer's gross profit, but it helps to maintain the sustainability of groundwater and surface water resources in Qazvin province.