Integrated river water quality and quantity management based on undesirability and cost‐effectiveness

Abstract

AbstractIntegrated water resources management aims to simultaneously solve water shortage and contamination problems by considering economic, social, and environmental criteria. To that view, this study has developed a two‐objective optimization model regarding water allocation (WA) and wasteload allocation (WLA) in the Zayandehrood river basin, the central part of Iran. The model aimed to supply the users' water demand considering the downstream environmental flow to fulfill the social‐environmental requirements. Besides, satisfying the river water quality standards was regarded as the environmental‐economic criteria. The WA objective function minimizes the undesirability caused by reduced allocated water and downstream environmental flow. The QUAL2K model was used to simulate the wasteload discharge impacts on the river water quality. The water quality parameters included biochemical oxygen demand (BOD), TP, and TN for the urban and industrial wasteload and nitrate for the agricultural drainage. The results showed that a joint WA ‐ WLA optimization reduced the total average WA by 15% and increased the downstream flow by three times the base level. Also, the water quality violations of the standard limits were reduced by 18, 4, and 15 times for BOD, NO3, and TP, respectively.