[Scenario analysis of integrated model of nutrients in the Miyun Reservoir and its watershed].

Supported by the integrated model of nutrients for the Miyun Reservoir in part I, effects of different control measures were studied on the water quality of the reservoir. Four scenarios were assumed and analyzed. Results of the base case scenario showed that TN concentration of the Miyun Reservoir had highly exceeded the environmental quality standard for surface water, and TP was relatively better. Furthermore, there were many regions that chlorophyll-a concentration exceeded 10 microg/L in the reservoir, and centralized in the reservoir area of Chaohe River. Scenario 1, 2 and 3 investigated effects of different pollution control measures on the water quality of the reservoir. Results showed that the control of nutrient input loads could improve the water quality greatly, especially control of TP loadings would limit algae growth effectively, and regions that chlorophyll-a concentration exceeded 10 microg/L even disappeared. The results indicated that some control measures, such as changing farming style, part treatment on stockbreeding pollution and reducing point source pollutant loadings were very effective and essential to decrease the eutrophic level of the reservoir.