River Water Quality Management with Conflicting Objectives: A Case Study

Available water resources are often not sufficient or too polluted to satisfy the needs of all water users. Therefore conflict over water, as a result of limitations on quantity and quality of water is a major challenge in water allocation. In this study, a methodology for river water quality management considering in water user/ stakeholders preferences satisfaction is presented. The dissatisfactions of each water user and stakeholders are the difference between the allocated water quality and quantity and the users' demand as well as water quality requirement of each user. The objective function of the optimization model is to minimize user dissatisfaction due to quality and quantity of allocated water to each sector and quality and quantity of wastewater and return flows discharged by each user to the river. To evaluate the spatial and temporal variation of the concentration of the water quality indicators in the system, a water quality simulation model is linked to a GA-based optimization model. The model is applied to the Karkheh river system in southwest of Iran. The results in forms of reliability, resiliency and vulnerability of the system are determined which show the significant value of the proposed methodology in river water quality management with conflicting objectives.