Interbasin Water Transfer Capacity Design by Two Approaches of Simulation-Optimization and Multicriteria Decision Making

Water resources management is a challenging problem in Iran and in many other locations because of the unbalanced temporal and spatial distribution of available water and demands. Interbasin water transfer, in which water is transmitted from a basin with high water availability to a neighbor basin with high water use, has been proposed as a solution to water scarcity. Because of the various decision-making factors, studies of interbasin water transfer projects have been presented as complex and difficult in the literature. In this paper, an optimum design for the capacities of the Behesht-Abad interbasin water transfer system, from the upstream Karoun basin to the Gavkhooni basin in central Iran, has been studied using a simulation-optimization approach in which particle swarm optimization (PSO) is coupled with the river basin simulation model, to find the optimum values for decision variables. In another approach, by use of multicriteria decision making (MCDM) and quantifying selected criteria in the source and target basins, the most beneficial scenario for water transfer is selected by prioritizing six possible alternatives. Results obtained by both PSO-MODSIM and MCDM approaches are close to each other and show that under conditions consistent with recent drought years, the optimum capacity of the water transfer tunnel is obtained to be a maximum of 45% of the capacity under conditions consistent with long-term historical discharges of the rivers. (C) 2017 American Society of Civil Engineers.