Evaluation of the hydrology and sediment load situations of the upper watershed of Thac Ba reservoir (Vietnam and China) under the impacts of climate changes

The Thac Ba reservoir serves as a critical supply of water for residents in Hanoi's downstream region, who rely on it for their livelihood. Recent changes in land use have resulted in a greater input of silt and nutrients into the environment. A large number of modeling studies have not been carried out because of the challenges in obtaining data from both China and Vietnam. The reservoir is located inside an international drainage basin that connects China and Vietnam. On the basis of the findings of the calibrated and verified SWAT model on streamflow and sediment, we provide this paper. On the basis of monthly data gathered from 1992 to 2003, the model's performance was extremely excellent in terms of the coefficient of determination (R-2) and the Nash-Sutcliffe coefficient (NSE), with R-2 = 0.885 and NSE = 0.914 for precipitation and R-2 = 0.826 and NSE = 0.849 for sediment, respectively. It was less accurate (NSE = 0.628) but remained dependable in the daily streamflow calibration case study. Based on climate change predictions for Vietnam, four scenarios were designed and assessed for this study. The case study also provides a quantitative illustration of how successfully GIS and SWAT can function together when the amount of meteorological data available is restricted. These findings will be useful in the administration of water and soil conservation initiatives in the future.