Assessment of climate change impact on future streamflow at Bernam river basin Malaysia

Climate change is anticipated to bring variability in future streamflows in various watersheds. Soil Water Assessment Tool (SWAT 2012 version) was evaluated using streamflow data (1976-2006), and assessed the potential impacts of climate change driven by projections from ten global climate models (GCMs) under three Representative Concentration Pathways (RCPs) scenarios (RCPs 4.5, 6.0 and 8.5) on future streamflow (2010-2039), (2040-2069) and (2070-2099) at the Bernam River Basin, Malaysia. The model efficiency during calibration and validation, with coefficient of determination (R-2), Nash-sutcliffe efficiency (NS), Percent Bias (PBIAS) and Root mean square error-standard deviation ratio (RSR) is 0.67, 0.62, -5.4 and 0.64; and 0.64, 0.61, -4.2 and 0.65, respectively. This shows that SWAT coupled with GIS extension is a good tool for continuous simulation. Future streamflow is projected to decrease in all future periods during main and off-seasons. However, the changes would be more pronounced during the off-season period with a significant decrease of -9.14 % under the worst-case scenario (RCP8.5). Therefore, the Basin may likely to experience tremendous pressure in the late century due to low streamflow, particularly during the off-season months.