Flow regime alteration analysis under climate change in Tonle Sap Subbasin

Climate change is considered as a major driving factor to intensify the challenges to the ecosystem. Critical flow condition which is occurred under climate change could lead issues to ecosystem and biodiversity. In contributing to this concern, Soil and Water Assessment Tool (SWAT) and Indicators of Hydrologic Alteration (IHA) were integrated to define the impact of climate change relevant to ecosystem. SWAT model presented a good performance on simulating daily streamflow in this research. As the result, model calibration was evaluated with statistical indicators of NSE=0.63, RSR=0.61, and PBIAS=-5.42%, while model validation obtained better performance of NSE=0.71, RSR=0.54, and PBIAS=-5.04%. The developed model was used to simulation streamflow under climate change scenarios. Three projected climate change models (GFDL-CM3, GISS-E2-R-CC, IPSL-CM5A-MR) with different two Representative Concentration Pathways (RCP2.6 and RCP8.5) in the 2030s, 2060s, and 2090s were selected. Results indicate that timing, frequency, magnitude, and variability are more likely to have great changes for GISS-E2-R-CC with both emissions, while result indicates small changes with GFDL-CM3 and IPSL-CM5A-MR models