Research On Water Pollution Prevention And Control Technology Of Shuangfengsi Reservoir Based On Hydrodynamic-water Quality Model

With the rapid development of social economy,people’s daily life,production and ecological water demand is getting larger and larger,and the requirements for water quality are becoming more and more stringent,but the random discharge of enterprise wastewater and domestic sewage further pollutes the water environment,making the water shortage problem upgrade from a single resource type water shortage to a resource-water quality water shortage.As a large（II.）type water conservancy and hydropower hub project recently built,the Shuangfengsi Reservoir plays a pivotal role in solving the problems of flood control safety,contradiction between supply and demand of water resources,and deterioration of the water environment in Chengde City.However,the reservoir is also facing the problem of water pollution,the reservoir area for hydrodynamic-water quality simulation analysis,analysis of the Shuangfengsi Reservoir in different flood processes under the water flow field and the migration of pollutants changes law,and further put forward with certain technical support of the treatment measures,to solve the reservoir area water quantity,water quality and other issues of practical significance.First of all,in the main stream and tributaries of the Wulie River,5 monitoring points,and 4 groundwater monitoring points in the submerged area of the reservoir area,the water from the reservoir and the water quality in the reservoir area were monitored respectively,and the TN concentration of the water in the upper reaches of the Shuangfengsi Reservoir was high,and the main pollution sources were the domestic sewage discharge,poultry breeding pollutant discharge,and the application of pesticides and fertilizers for agricultural planting in villages and towns along the river upstream.Secondly,taking the 100-year design flood process deduced by the typical flood process as the upper boundary,taking the water level flow process curve as the lower boundary of the model,and combining the terrain of the reservoir area to carry out triangular grid treatment of the reservoir area,the MIKE21 hydrodynamic model of the Twin Peaks Temple Reservoir was established,the reservoir was divided into 4905calculation units,and the parameter rate was determined,on this basis,the 1994 measured flood process was introduced to verify the model,and the model could better reflect the hydrodynamic field of the Twin Peaks Temple Reservoir.On the basis of hydrodynamic simulation,the pollutant concentration data and water quality parameters are applied to the ECO Lab module in the MIKE21 model to form a coupling hydrodynamic-water quality model,and the distribution and change of water quality in the reservoir area are simulated and analyzed.The variation curve of the concentrations of BOD,DO,NH₄,NO₃ and PO₄ under the flood process was obtained by simulation,and the evolution of the concentrations of pollutants in the reservoir area and the pre-dam section with the flood process was further obtained.Finally,in order to further improve the water quality of the reservoir,three preventive and control measures are proposed with reference to the model simulation results.（1）Control the pollution sources upstream of the reservoir to reduce the discharge of domestic and industrial sewage and the amount of agricultural fertilizer and pesticide application;（2）Plan and build surface flow artificial wetlands at the reservoir entrance,jointly use the wetlands in the upstream of the reservoir and the wetlands in the tailwater area of the reservoir,and improve the quality of the water quality of the reservoir through bio-ecological restoration and other technologies;（3）Strengthen the monitoring of water quantity and water quality,and combine the coupling model of reservoir hydrodynamics and water quality to form a combined water purification model.