Optimal Cropping Pattern and Management of Ground and Surface Water Resources of Kohpayeh-Segzi Plain Using the Integrated Model of Game Theory and Optimization Algorithm

In recent years, the conflict between environmental interests and farmers' livelihoods has emerged as one of the most crucial issues in the environmental and agricultural governance of the Zayandeh-Rood watershed. Hence, achieving a balance between economic profitability through the use of an optimal cropping pattern and preventing the excessive extraction of groundwater resources holds great importance for policymakers in this field. In this study, the environmental function was modeled by considering water resources limitation, while the economic function was modeled based on the economic profit derived from the cultivated crops in Kohpayeh-Segzi Plain in 1996-2011. The Nash function was optimized by using constrained nonlinear optimization by taking into account the limitation of water resources in each year. After optimizing the Nash function, the cropping pattern was determined using both game theory (GT) method and linear programming (LP) method. Results indicated 30% reduction in water consumption with the GT and 17% reduction with the LP method. Additionally, the profit reductions for these two methods were 16% and 3%, respectively, compared to the base case. Furthermore, the results revealed that the groundwater level in the representative hydrograph of the plain decreased by 3.94 and 2.23 m in the GT and LP methods, respectively. Conversely, in the optimized GT method with an economic function weight of 0.5, the groundwater level of the plain increased by 8.67 m. Considering the reduction of water consumption, profit reduction, and the increase in groundwater level, the optimized GT method with a weight of 0.5 was superior to the LP method.