Assessment of Water Management Scenarios and the Impact of Climate Change on Environmental and Agricultural Sustainability (Case Study: Zarrinehrud and Siminehrud River Basins)

Urmia Lake, as a hyper saline and very shallow lake, located in the northwest of Iran, has had reduced water level of about 40 centimeters each year over the past two decades and is drying, which this problem has led to social and environmental consequences. In this research, the indexes of environmental and agricultural sustainability were evaluated using performance criteria influenced by climate change and water management strategies for the Zerrinehrud and Siminehrud river basins as the largest sub-basin of Urmia Lake Basin. Modeling of hydrologic behavior of these basins was performed by WEAP21 model. The LARS-WG downscaling model was used to simulate climate change.Then the model was analyzed for three future emission scenarios (A2, A1B and B1), for the period 2015-2040, and five water management scenarios: (1) keeping the existing situation (S0), (2) crop pattern change (S1), (3) improving the conveyance and distribution efficiency (S2), (4) combining the improvement of conveyance and distribution efficiency with improving the application efficiency using modern technology (S3), and (5) the combination of crop pattern change with the improvement of total irrigation efficiency (S4). The results showed that the highest values of indices ​​of environmental sustainability and agricultural sustainability were related to the scenario of combining the crop pattern change with improving the total irrigation efficiency under the B1 emission scenario (B1S4). In this scenario, the average annual flow of water entering the Urmia Lake from Zarrinehrud and Siminehrud river basins will be equal to 1292 and 351 MCM per year, and as a result, the environmental flow requirements of the lake will be supplied from these basins.