Climate change impacts under CMIP5 RCP scenarios on water resources of the Kelantan River Basin, Malaysia

Abstract

This study aims to evaluate the potential impacts of climate change on water resources of the Kelantan River Basin in north-eastern Peninsular Malaysia using the Soil and Water Assessment Tool (SWAT) model. Thirty-six downscaled climate projections from five General Circulation Models (GCMs) under the three Representative Concentration Pathways (RCPs) 2.6, 4.5 and 8.5 scenarios for the periods of 2015–2044 and 2045–2074 were incorporated into the calibrated SWAT model. Differences of these scenarios were calculated by comparing to the 1975–2004 baseline period. Overall, the SWAT model performed well in monthly streamflow simulation, with the Nash-Sutcliffe efficiency values of 0.75 and 0.63 for calibration and validation, respectively. Based on the ensemble of five GCMs, the annual rainfall and maximum temperature are projected to increase by 1.2–8.7% and 0.6–2.1 °C, respectively. This corresponds to the increases in the annual streamflow (14.6–27.2%), evapotranspiration (0.3–2.7%), surface runoff (46.8–90.2%) and water yield (14.2–26.5%) components. The study shows an increase of monthly rainfall during the wet season, and decrease during the dry season. Therefore, the monthly streamflow and surface runoff are likely to increase significantly in November, December and January. In addition, slight decreases in the monthly water yield are found between June and October (1.9–8.9%) during the 2015–2044 period. These findings could act as a scientific reference to develop better climate adaptation strategies.