Study of climate change effects on hydrological processes in Siminehroud and Zarrinehroud watersheds northwest of Iran

This study sets out to simulate various hydrological responses to climate change. The semi-distributed hydrologic model of the Soil and Water Assessment Tool, SWAT, was used to simulate different parts of the hydrological cycles. The comprehensive assessment of the effect of climate change on runoff, crop yield, and water balance in Siminehroud and Zarrinehroud watersheds is the novelty of this research. The simulation period was from 1988 to 2014. The runoff model was calibrated using the plant parameters, and the initial crop yield was used to calibrate the model. During the calibration and validation periods, the statistical measures, namely NS and R 2 , were obtained as 0.69 and 0.82, respectively. Using the multisite statistical downscaling of the LARS-WG climate model, we introduced the future climatic conditions as inputs to the model based on two optimistic (RCP2.6) and pessimistic (RCP8.5) scenarios. The most significant changes in the runoff in the upcoming period, was in June, reduced by 4.2 m 3 s −1 , and in May, increased by 4.8 m 3 s −1 in the optimistic scenario. In the RCP8.5 pessimistic scenario, the most significant runoff change was observed in June and October. The results indicated that these changes would lead to a decrease in the main crops across the region.