Improving the management of agricultural water resources to provide Gavkhuni wetland ecological water right in Iran

One of the main approaches for wetlands rehabilitation is improving water management in the agricultural sector and reallocation of stored water to the environmental sector. Due to the over-water harvesting from the Zayandehrud River (mainly for agricultural purposes), the Gavkhuni wetland in central Iran is facing serious water stress. Hence, the aim of this study is to rehabilitate the Gavkhuni wetland by considering the water management scenarios in the agricultural sector. These scenarios are modernization and upgrading the operation of agricultural water distribution systems (A), upgrading in-farm irrigation systems (B), optimizing the cultivation pattern (C) and reducing the utilization of groundwater resources (D), and combining these scenarios together as strategic scenarios to provide ecological water right. In order to evaluate the strategic scenarios for allocating water resources to the wetland, the Zayandehrud basin was simulated using the WEAP model by considering the water resources and uses. For evaluating the presented scenarios based on the sustainable development indicators and due to the uncertainty and intuitive judgment of decision-makers, the fuzzy-CP model was applied. The results showed that water consumption management in the agricultural sector plays a significant role in increasing the inflow to the wetland. This is achieved through the modernization and upgrading of agricultural water distribution systems using two approaches: centralized control (model predictive control) and decentralized control system (proportional-integral), which improve irrigation efficiency by 13.1%, modify cropping patterns by 18.8%, and reduce groundwater extraction by 30%, resulting in a 49.1 and 19.1% increase in inflow to the wetland, respectively. Additionally, the combination of four scenarios indicated a more than 100% increase in the inflow volume to the wetland. The prioritization of scenarios based on a fuzzy agreement multi-criteria decision-making model demonstrated that scenarios ABCD, ACD, and A have a higher priority in increasing the inflow to the wetland compared to other scenarios.