Evaluating the Effect of Sefidrud Irrigation and Drainage Network on Marginal Value of Irrigation Water in Gilan Province

Limited water resources, lack of rainfalls, population growth and standard of living, causing severe imbalance between supply and demand of water. Economic instruments such as the pricing and the development of irrigation networks can be seen as a solution for this is balance. Therefore, the aim of this study is to measuring the water marginal value difference between traditional lands and lands in the Sefidrud irrigation and drainage network in Gilan Province to the economic value created by the network of irrigation water in agriculture should be evaluated. For this purpose, by using the linear programming model, shadow prices for irrigation water for each of the seven regions of the province, including the four areas outside of Sefidrud network and the three areas inside of it was estimated. The results showed that the maximum economic value per cubic meter of water, 3096 Rials for Fomanat inside of network and the minimum economic value per cubic meter, 1598 Rials for upstream Sangar dam outside of network. Due to the weight of the acreage in each region, the average yield per cubic meter of water in the region in 2622 and 2215 Rials, respectively inside and outside the network. In other words, the additional net benefit of irrigation and drainage network is only about 400 Rials per cubic meter of water consumption. Based on research findings, each additional cubic meter of water supply, has created different values in irrigation areas of Gilan province that it represents the Importance of water allocation policies. It is suggested that, according to target subsidies law and in accordance with the values obtained, in a long-term schedule, water tariff increase in agricultural prices.