Evaluation of climate change effects on flood frequency in arid and semi-arid basins

Climate change (CC) will increase the intensity of extreme phenomena such as drought and flood in arid and semi-arid regions. This will cause the water supply of these areas to become very difficult in times of crisis. This study identifies sub-basins with high flood potential in the baseline period (1982-2005) and the future period (2025-2048) in the Hablehroud basin, north-central Iran. It uses the soil and water assessment tool (SWAT) and 23 coupled model intercomparison project 5 (CMIP5) general circulation models (GCMs). It estimates the instantaneous peak flow (IPF) and uses a flood index (FI) to determine the contributions of each sub-basin to the floods. The rainfall of the basin will increase by 11.5% under representative concentration pathway (RCP) 4.5 and 12.6% under RCP 8.5. The minimum daily temperature (Tmin) of the basin will increase by 0.8 degrees C under RCP 4.5 and 1.1 degrees C under RCP 8.5 in the future period. In addition, the maximum daily temperature (Tmax) will rise by 1 degrees C under RCP 4.5 and 1.2 degrees C under RCP 8.5. Moreover, basin runoff will increase by 6.4% under RCP 4.5 and 11.6% under RCP 8.5. The results indicate that the central and southern sub-basins made the most significant contribution to floods in the baseline period, while the eastern sub-basins will make the most considerable contribution to future floods.