Abstract
Climate change affects streamflow through changes in precipitation, temperature, and
extreme weather events. These changes will impact water resource availability significantly.
Thus, understanding the impacts of climate change on hydrology is essential for sustainable
water management. This study investigated the potential effects of climate change on
streamflow in the Olifants River basin under shared socioeconomic pathways (SSPs),
utilizing the restructured version of the Soil andWater Assessment Tool (SWAT+) model.
Projected precipitation and temperature (Tmax and Tmin) were analyzed for the near
(2030–2060) and far (2070–2100) future to simulate and analyze streamflow variations under
SSP245 and SSP585 scenarios using bias-corrected CMIP6 data and the SWAT+ model. The
SWAT+ model was calibrated and validated successfully, with Nash–Sutcliffe efficiency
(NSE) values of 0.76 and 0.77, and coefficient of determination (R2) values of 0.78 and
0.82 during the calibration and validation periods, respectively. Climate model ensemble
projections show a consistent decline in precipitation and increases in Tmax and Tmin, with
Tmin increasing more significantly. These changes are projected to reduce streamflow, with
annual declines of 43.08% and 50.89% under SSP245 and 57.79% and 58.82% under SSP585
for the near and far future, respectively. Moreover, climate change reduces streamflow
across all seasons in the Olifants River basin. Therefore, adopting water management
strategies such as enhancing integrated water resource management and investing in
climate-resilient infrastructure is essential for sustainable water resource management
under changing climate conditions in the basin.