Assessment of Climate Change Impacts on the Hydrological Behavior of the Sarbaz River Basin Using CMIP۶ Climate Models

This study introduces a framework for assessing climate change and flow conditions by integrating the latest climate simulations from the CMIP۶ project (HadGEM۳-GC۳۱-LL model) with the Soil and Water Assessment Tool (SWAT), while also evaluating the influence of different climate model resolutions. A total of ۶۶ hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were calculated to assess future extreme flows in the Sarbaz River Basin, located in Sistan Province, which is particularly vulnerable to flooding. Results indicate that by the ۲۰۳۰–۲۰۵۰ period, compared to the baseline period of ۱۹۹۰–۲۰۱۹, annual precipitation, streamflow, and maximum and minimum temperatures are projected to increase by ۶.۹%, ۹.۹%, ۰.۸°C, and ۰.۹°C, respectively. Monthly precipitation and streamflow are expected to rise especially during the monsoon season (June–September) and early wet periods (December). The magnitude of minimum ۱-, ۳-, ۷-, ۳۰-, and ۹۰-day flows is projected to increase by ۷.۲% to ۸.۲%, while peak flows could rise by ۱۰.۴% to ۲۸.۴%. Finally, significant differences were observed between high- and low-resolution climate models, with high-resolution models predicting an ۱۱.۸% increase in average monthly flows during November–January, compared to just ۳.۲% in low-resolution models.

Keywords:

Climate change , Sarbaz River Basin , SWAT Model , CMIP۶ Models , Hydrologic Indicators (IHA)