Research on Environmental Impact of the Dianzhong Water Diversion Project Using Erhai Lake as a Regulation and Storage Reservoir

The water volume of the Dianzhong Water Diversion Project from Jinsha River average annual water diversion is 3. 403 billion m³. In order to solve the environmental adverse effects such as no on-line regulation and storage of water in the main canal of water conveyance and alleviating the water environment and ecology brought by diversion of Jinsha River,research and demonstration on scheme of water diversion and storage of Erhai Lake in Yunnan Province were conducted. In this paper,two-dimensional water quality mathematical model of Erhai Lake was used to predict the change of quality of Erhai Lake under the scheme of engineering utilization of Erhai Lake for water storage. The research showed that the concentration of TN and TP in Erhai Lake has been increased by utilizing the storage scheme of Erhai Lake,which has a greater influence on the concentration of TP. The concentration of TP has deteriorated from Category Ⅱ to Category Ⅲ; The Jinsha River fishes,especially Schizothorax fishes and loaches,entered the Erhai Lake and along the reservoir along the Lancang River with water flow after the reservoir was regulated and stored in Erhai Lake. There is a risk of aquatic organisms invading across river basins and the experimental Area of Erhai National Natural Reserve in Cangshan,Dali. From the point of view of environmental protection,it is not recommended to use Erhai Lake for storage.