Author(s): Yiping Li; Chunyan Tang; Li Qiu; Zhongbo Yu; Kumud Acharya
Linked Author(s): Yu Zhongbo
Keywords: EFDC; Eutrophication; Shallow lake; Water age; Water transfer
Abstract: To enhance the water exchange and mitigate eutrophication in Lake Taihu, the third largest freshwater lake in China, a water transfer project was applied in 2002 to transfer water from Yangtze River to flush pollutants out of Lake Taihu. However, the water transfer engineering could not significantly enhance water exchange in the Meiliang and Zhushan bays, the most polluted areas of Lake Taihu. Recently, new Meiliang pump station has been put into practice to accelerate the water exchange and mitigate the eutrophication in Lake Taihu. The process and effectiveness of Meiliang pump station and water transfer project were investigated in this study by using a three-dimensional hydrodynamic model, Environmental Fluid Dynamics Code (EFDC), based on the concept of water age. Model results showed that the effectiveness of water transfer projects was strongly associated with the inflow or outflow rate of Meiliang pump station and the winds condition. In terms of flushing effect and cost, the economically effective influent flow rate from Wangyu River was predicted to be 120 m3/s, and the corresponding most suitable outflow rate from the Meiliang pump station was about 15 to 20 m3/s based on multi-objective programming. Southeasterly winds—dominant in the summer—could enhance the performance of water transfer on improving water quality in Meiliang Bay and eastern areas of the lake. In general, new-built Meiliang pump station played a supplementary role for Yangtze River water transfer engineering in mitigating eutrophication in parts of the lake rather than the entire lake, suggesting that water transfer projects can only be used as an emergency measure for alleviating algal bloom in part of Lake Taihu.