Evaluating the Effects of the Sefidrud Network Inflow Reduction on Crop Pattern in Central Valley of Guilan Province

The big Sefidrud basin supplies the irrigation water of the Guilan fertile plain and provides requested water for strategic crop of rice in mentioned province. Water resource development projects in upstream of mentioned basin، risks supplying guaranteed irrigation water for Guilan plain. Present study investigates the effects of ten Sefidrud network inflow reduction scenarios under eight irrigation network conditions using regional mathematical programming based on positive mathematical programming and considering hydrological situations in central valley irrigation district of Guilan province. Requested data sets were obtained from Iran''s water resource management company، Guilan Water Company and different consultants'' researches. Acreages removed from irrigation module، avoided loss because of applying irrigation efficiency improvement projects and reduced gross margins of cultivation incentral valley irrigation district under different inflow reduction scenarios and network condition are the most important results of this study. Results revealed that nine percent reduction of the Sefidrud irrigation and drainage network inflow in central valley under current network condition caused 7. 6 percent of rice acreages and 7. 9 percent of total crops acreages to remove from irrigation module. Simulations based on changes in network condition showed the considerable effect of irrigation efficiency improvement policy on avoiding loss due to inflow reduction. Mentioned results provide a base for cost-benefit analysis of irrigation efficiency improvement projects in this irrigation district.