Hydro-economic Simulation-Optimization Model for Optimal Design of Water Resources Development Projects and Policies in Helleh River Basin

This paper deals with developing a hydro-economic simulation-optimization model for optimal design of water resources development projects and policies of Helleh (Shapoor-Dalaki) River Basin, located at south of Iran, over a long-term planning horizon. We employ Particle Swarm Optimization (PSO) coupled with a simulation model which is a combination of WEAP water allocation software and three computational modules for soil and water salt routing at basin scale, crop yield production and economic analysis. Finally we apply the developed simulation-optimization model to optimize infrastructural projects and measures, e.g. construction of dams and irrigation districts and utilization of modern technologies, and also operation policies, e.g. irrigation and leaching strategies, reservoir rule curves, and water allocation priorities. Model application results suggest construction of Choroom, Dalaki and Nargesi dams with normal water volumes equal to 43.5, 305.5 and 76.8 million cubic meters, respectively. In spite of economic efficiency of the optimal solution achieved (18% enhancement of net benefit), the associated economic value of water is reduced with respect to business-as-usual condition. Also optimal irrigation and leaching strategies lead to 35% reduction in total gross irrigation requirement under development condition.