Applying environmental models to determine total maximum daily loads for reservoir watershed management

To protect the reservoir water quality, it is required to control and reduce the pollution sources in its upstream watershed area. This study applies the EPA’s Storm Water Management Model and the Vollenweider model to assess the relationship between the pollution sources in the Luliao Reservoir Watershed and the water quality of the Luliao Reservoir. The purpose of this study is to determine the total maximum daily loads in the watershed on the basis of a target water quality concentration of the receiving waterbody. The results show that the allowable total phosphorous (TP) load is about 855 kg/yr when considering a target TP concentration of 24 μg/L. To reach this target, the TP load needs to have about 1222 kg/yr reduction. Moreover, this study analyzes the spatial variation of TP load and the pollution hotspots in the Luliao Reservoir Watershed. The pollution control and reduction strategies are recommended to preferentially implement in the pollution hotspots.