Multi-objective optimization of quantitative-qualitative operation of water resources systems with approach of supplying environmental demands of Shadegan Wetland

Irregular withdrawals from water resources followed by the increase of the cultivation lands and the construction of Marun and Jarahi Dams on upstream rivers of the Shadegan Wetland have led to severe hydrological changes as well as increased salinity of the wetland inflow in some periods. The aim of this study is to develop a simulator-optimizer coupling model for proper planning and management of resource allocation to the upstream of Shadegan Wetland. In addition to maximizing the supply of basin demands during the operation period, this model aims to reduce the salinity of the inflow to Shadegan Wetland. Due to the importance of the wetland as a seasonal habitat for birds and the importance of protecting its ecosystem, the development of a quantitativequalitative optimization model for optimal use of available water resources is the aim of this study. First, based on current conditions, the prepared model is developed as a reference scenario for a future 30-year period (2021-2050). To achieve the best system efficiency in terms of quality and quantity, the optimization is performed by means of the NSGA-II algorithm. The results indicate that the optimizer model performs appropriately in supplying various demands and also decreasing the salinity of the inflow to Shadegan Wetland compared to the reference scenario so that in addition to supplying the demands with more than92% reliability in the whole system, it is expected that the salinity of the river at the entrance to Shadegan Wetland to be reduced by about50%., especially in low water months. The coupling model proposed in this research is applicable for other study areas with quantitative-qualitative operation approach and is able to detect critical points of rivers in terms of quantity and quality. This model has also the capability of providing optimal solutions for improving river conditions as well as downstream ecosystems.