Comprehensive assessment and scenario simulation for the future of the hydrological processes in Dez river basin, Iran

Abstract

Climate change is one of the leading factors that directly affect hydrological processes in large basins. This study assesses the impacts of climate change on streamflow, sediment and crop yield, actual evapotranspiration (AET), and water budget. In addition, the effects of land use and land cover (LULC) alteration with climate change on streamflow and sediment yield have been evaluated in the Dez river basin in the southwest of Iran. Five General Circulation Models (GCMs) based on two scenarios, Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 for the near period (2021–2040) are considered. Hydrological simulation is performed using the Soil and Water assessment tool (SWAT) with good performance in the calibration (1990 to 2010) and validation (2010 to 2017) periods. The precipitation and temperature projected show a major upward trend related to the base period. The results showed that climate change increases the runoff and sediments. In addition, results projected that garden crop yields would increase while agricultural crop yields would decrease. In addition, AET will face a slight decline of about 2%–6%. Combined LULC and climate change scenarios showed that with amplification of orchards areas, sediment load would decrease. HIGHLIGHTS Climate change increases the runoff and sediments.; Evaluate the impacts of climate change on streamflow, sediment yield, crop yield, actual evapotranspiration, and water budget.; Set up a comprehensive model for multifunctional calibration of hydrological processes.;

Keywords

• crop simulation
• dez dam
• land use change
• sediment
• zagros mountains