Main Article Content
The goal of this study is to examine the responses of hydrology and water resource availability to future climate change in the 3S (Sekong, Sesan, and Srepok) river basin located in the tropical countries of Laos, Vietnam, and Cambodia. The calibrated the Soil and Water Assessment Tool (SWAT) model was used to investigate changes to the hydrological regime and water resources under various climate change scenarios. The climate change scenarios were designed based on an ensemble of 5 GCM simulations (HadGEM2-AO, CanESM2, ISPL-CM5A-LR, CNRMCM5, and MPI-ESM-MR) for medium emission (RCP4.5) and high emission (RCP8.5) scenarios. The climate of the basin was prognosticated to be warmer and wetter with increased temperature and precipitation in the future. Future climate change causes an increase in stream flow from 29.0 to 45.0%, 2.0 to 8.3%, and 1.2 to 10.6% for the Srepok, Sekong, and Sesan rivers, respectively. Although the discharge is projected to increase in the future, the per capita water availability is projected to decrease to 48.5, 55.1, and 80.2% in the 2090s compared to 2010 for the Srepok, Sekong, and Sesan rivers, respectively, due to population growth. The Sekong and Srepok basins will experience the most serious decline in trend and absolute value of water availability, respectively. The results of this study will be helpful to water resource development, planning, and management under climate change scenarios in the 3S river basin (3SRB).