Application of water quality model to analyze pollution hotspots and the impact on reservoir eutrophication

Sustainable reservoir watershed management is crucial to maintain a water supply system. The purpose of this study is to assess the pollution sources of the Bao-Shan Reservoir, which is an off-stream reservoir and is the study reservoir herein. Most water source of the Bao-Shan Reservoir is from the Shang-Ping Watershed. This study applies the EPA’s Storm Water Management Model (SWMM) and the Vollenweider model (VM) to analyze the pollution hotspots in the reservoir watershed and the impact of the pollutions on the reservoir water quality. The results indicate that non-point source pollution is the main pollution in the Shang-Ping Watershed. The pollution hotspots are located in the sub-watersheds S1, S3, S4, and S5. These sub-watersheds have higher total phosphorus (TP) loads per unit area. In order to protect the water quality of the Bao-Shan Reservoir, this study suggests that the TP load entering the reservoir needs to be reduced by about 16% to 24%. The control of non-point source pollution needs to be preferentially implemented in the Shang-Ping Watershed. The analysis and discussion in this study are a useful reference for reservoir watershed management.