Iterative Framework for Robust Reclaimed Wastewater Allocation in a Changing Environment Using Multi-Criteria Decision Making

In this study, an iterative framework for robust reclaimed wastewater allocation (IFRWA) was developed to consider multiple climate change scenarios using multi-criteria decision making (MCDM) methods. Each iteration begins with the assumption that an additional unit of water quantity is allocated to reclaimed wastewater (RWW) sites. Based on these allocation conditions, hydrologic simulations are performed and evaluated using the incremental alternative evaluation index (IAEI) to rank the best sites for each unit water quantity. The minimax regret strategy is employed to consider the uncertainty inherent in the climate change scenarios. The consequent robust ranking of the IAEIs is applied to determine the final allocation of the unit water quantity in a given iteration. This iteration continues until the total allocated water quantity satisfies the maximum available capacity of RWW for use in the studied watershed. Our results show that this incremental and robust framework can be used to determine the reasonable capacities of RWW at multiple sites within the watershed by considering various aspects of RWW use, including the water quantity and the socio-economic aspects of decision making. A choice and concentration strategy based on IAEIs should be employed to achieve the maximum utility considering the physical constraints (capacity and cost). If economic considerations, such as the cost of construction and management, are included, this framework can be applied to real problems.