Simultaneous effects of climate and land use change on watershed hydrological processes

This research aims to investigate simultaneous effects of climate change and land use change on runoff and real and potential evapotranspiration in Mehrgerd Watershed in South Western Iran. To this end, land use maps were produced for years 1987, 2002, and 2017. Then, 2032 map was predicted. Future projections of the Canadian earth system model (CanESM2) model based on representative concentration pathway 8.5 (RCP8.5) emission scenario were used. The projections were downscaled by statistical downscaling model (SDSM) to simulate future climate of the watershed during 2017-2032. Model of soil and water assessment tool (SWAT) was employed to simulate watershed's hydrological processes. R2 and NSE for calibration were 0.73, 0.69, respectively. The values for validation were 0.71 and 0.58, respectively. The results showed the contribution of climate change to runoff and real and potential evapotranspiration was 76%, 74%, and 90%, respectively. Furthermore, the land use change contribution to the mentioned components was 24%, 26%, and 10%, respectively. Therefore, effects of climate change on runoff and real and potential evapotranspiration was more significant than that of land use change.