Assessment of Changes in Agricultural Crop Yields and Inflows to Lake Urmia in Zarrinehrud River Basin Due to Changing Irrigation Systems from Surface to

Lake Urmia (LU) is the largest salt lake in the country. The lake’s level has extremely declined due to the increase in irrigated agricultural lands and the recent droughts. This condition has caused many environmental problems for the lake and the surrounding area. To resolve this problem, increasing irrigation efficiency is expressed as one the fundamental solutions to reduce water consumption and improve the rate of river inflows to LU. To assess this strategy, Zarrinerud River basin as the largest catchment of the LU basin was chosen as the study area to investigate effectiveness of this strategy. Furthermore, the Soil and Water Assessment Tools (SWAT) model was chosen and applied for the required simulations. For this, in the first step, the model was calibrated and validated using 6 gauging stations. Then, the basin’s actual evapotranspiration and crop production were calibrated, which resulted R2 more than 80%. The calibrated model along with the applied arrangements in the model were used to simulate changes in irrigation methods from surface (efficiency of 38%) to sprinkler (efficiency of 60%) and drip irrigation (efficiency of 80%). The results showed up to 20% increase in crop yields comparing with the current condition. But, the annual volume of water entering the lake didn’t significantly change and the decrease of water table was more severe. Therefore, it concluded that the pressurized irrigation cannot be considered as a fundamental measure to save Lake Urmia.