Application of Game Theory to Determining Optimal Harvesting of Water Resources (case study: Gharesu basin)

Abstract

Background and objective: Determining the optimal water consumption in Iran with a large percentage of arid and semi-arid climates is important. several methods, including linear and goal programming, have been used for this purpose. Applying Game Theory Method to Solve Management Problems that Facing Conflicts between Goals can be a different approach to optimizing water use in agriculture. It can offer a different approach to optimizing water use in agriculture, therefore in this study cropp pattern and the optimal harvesting of groundwater resources was determined in Ghare-Su basin. Materials and methods: Golestan province has less rainfall than other northern provinces despite being located in northern parts of Iran. Most of the demand water in this province is supplied by groundwater resources, which, if not properly managed, will face the risks of reducing groundwater aquifers level. So the cities of Gorgan and Kordkuy in west of Golestan province, located in Gharasso basin, are considered as a study area in this research. After providing information on the area of cultivation, the cost of production and the price of sales of major agricultural products, net irrigation demand was calculated considering irrigation efficiency the potential of water resorces and recharge basin from Regional Water Company of golestan. After preparing the data with considering water resource constraints and arable lands and also considering the goals of increasing profits and reducing water use to optimize the water harvesting values was determined by game theory conflict resolution methodology that including non-symmetric Nash equilibrium, Kalai-Smordinsky solution, area monotic solution and equal loss function method. Results: The optimal operation of water resources with non-symmetric Nash equilibrium, Kalai-Smordinsky solution and equal loss function method of game theory while considering equal weight for economic and environmental purposes and It is equal to 205 million cubic meters per year and optimum harvesting value was obtained 183 million cubic meters per year by using area monotic solution. This is in a situation that is considered for economic purposes as 0.575 weight and for environmental purposes as a weight 0.475. Therefore, the harvesting of water resources can be reduced by 43% to 49% to achieve environmental goals. In this method, planting of crops such as cotton, tomato, barley and soybean in Gorgan and barley in Kordkoye city is not recommended. Wheat is also the most cultivated area in Gorgan and spring soybean in Kordkoye. Conclusion: The results showed that is no optimal crop pattern in the current condition and the current harvesting value is higher than the aquifer recharge. Therefore, using game theory, can determine the crop pattern and optimal harvesting value that economic and environmental goals were met by applying different weights.