Uncertainty assessment of streamflow projection under the impact of climate change in the Lower Mekong Basin: a case study of the Srepok River Basin, Vietnam

Uncertainty assessment of future projection of streamflow is of the essence for an effective formulation of water resources management and planning adaptive to climate change. The aim of this study is to investigate the uncertainty in streamflow projection under the climate change impact in the Srepok River Basin. Uncertainty associated with emission scenarios (RCP2.6, RCP4.5 and RCP8.5), General Circulation Models (GCMs) (CanESM2, CNMR-CM5 and HadGEM2-AO), statistical downscaling methods (delta change method, quantile mapping and SDSM), and hydrological models (ANN, HEC-HMS and SWAT) is examined. The results showed the largest uncertainty source of the streamflow projection is the GCM simulations, followed by the statistical downscaling methods, hydrological models and emission scenarios. In addition, the use of hydrological models has a considerable impact on uncertainty in the simulations of dry seasonal streamflow. Generally, the present study highlighted the importance of using multi-GCMs in the studies on hydrological impact of climate change.