Developing an optimization model for conjunctive use of water resources and cultivation area allocation by game theory application

In the presented study, a multiobjective optimization-simulation model was developed to al-locate optimal water, cultivation area and crop pattern to different agricultural sectors. The sectors are located at a region encompassed by three cities; Minoo dasht, Azad shahr and Gonbad kavoos, in Golestan province. The model is a Surface-Groundwater conjunctive use model in which Modflow-GMS model is used to simulate groundwater flow. In the optimiza-tion part, the objectives consist of the maximization of the equity, agricultural benefit and green water ratio. Also, the constraints are related to maximum drawdown in water table, minimum and maximum volume of the reservoir, budget equation, release and cultivation ar-ea. After running the model by multiobjective genetic algorithm method, a pareto solution curve including 63 solution points obtained. The most preferable solution is selected by Con-dorcet method. Then different cooperative game theory method are applied to reallocate the benefit due to forming the grand coalition among the sectors. The results show that the amount of allocated water is a function of the summer crops area. Also it is shown that the most benefit is obtained for Gonbad kavoos, while the most benefit per cultivation area is for Minoo dasht. After that, the grand coalition forming causes to increase benefit up to 14864×109 Rial (20 percent growth). To reallocate benefit among the regions, different coop-erative game methods are applied. The results show that the most reallocated benefit for Minoo dasht, Azad shahr and Gonbad kavoos are obtained from normal nucleolus, nucleolus and proportional nucleolus, respectively.