Research On Water Replenishment Of Changlingpi Reservoir Based On Dasha River Environment And Ecological Demand

In recent years,with the promulgation of the State Council's "Ten Waters",people pay more and more attention to the urban river water environment.Urban rivers are an important part of an urban ecosystem,but due to the development of urbanization,urban river ecosystems have been severely damaged,water have been continuously polluted,urban water resources are scarce,even the phenomenon of black and odor of water body appears.Therefore,it is of great significance to manage the distribution of water resources,maintain sustainable urban development,and coordinate the relationship between people and nature.Dasha River is a rain-derived river.Due to the lack of external water supply,its water environment capacity is mainly affected by rainfall.However,the seasonal variation of rainfall in Shenzhen is extremely large,and the rainfall is mainly distributed in the flood season from April to September.Therefore,the seasonal change of the flow of Dasha River is obvious.During the dry season of the river,when the amount of water in the river is insufficient to meet the ecological needs,there will often be river outages,long-term retention of pollutants and even black and odor problems.It can be seen that the ecological replenishment of rain-sourced rivers is the key to the management of urban rivers.The concept of "minimum acceptable flow" that has been proposed by the United Kingdom earlier has laid the foundation for ecological water replenishment.In the subsequent development of river ecological governance,many excellent cases at home and abroad have also been derived,such as the restoration of the Cheonggyecheon River in South Korea,the water of Yinchao Lake in Hefei,and the water diversion project of Waicheng River in Suzhou.In general,ecological water replenishment is an innovative approach to urban water environment management.As an important landscape river in Shenzhen,Dasha River flows through high-tech areas such as the University City on the upstream,and the "Dasha River Ecological Corridor Park" created on the downstream affects people's daily lives.Therefore,it is of great significance to make ecological water supply to the Dasha River Basin.At present,domestic and international research on ecological water replenishment mainly focuses on the improvement of ecological water replenishment on rivers,and the quantitative relationship between water replenishment volume and river water quality has not been established,resulting in low ecological water replenishment efficiency and low water resource utilization efficiency.This paper collects and samples the water quality data of each monitoring section of Dasha River.Based on the assessment of the Dasha River water environment and water ecology status,combined with the actual water replenishment of the Changlingbei Reservoir during the dry season of 2018-2019,seven monitoring sections including DSH1-DSH7 were selected from upstream to downstream according to the actual conditions of the Dasha River Basin.Implementlong-term monitoring research on water environment-aquatic ecological indicators under water supplementation.The comprehensive pollution index method is used to evaluate the spatial water environment characteristics of the Dasha River,and the pollution sharing rate of each indicator relative to each monitoring section is calculated,and the main pollution indicators of the surface water in the Dasha River Basin are BOD,COD,and permanganate index.,total phosphorus,ammonia nitrogen,these indicators relative to the average pollution sharing rate of each monitoring section is88%.Using SPSS,the relationship between water environment and water ecological index factors in the Dasha River Basin was analyzed.Based on the long-term monitoring data of the water environment and aquatic ecology of the Dasha River during the water replenishment period,the mathematical model of the relationship between the flow and velocity of the Dasha River and the water environment-aquatic ecological factors of the Dasha River was studied,and a series of unary and multiple linear regression model were obtained.Each model can well calculate the quantitative impact of ecological water supplementation on various water environments and aquatic ecological parameters.The model results show that all environmental factors decrease with the increase of flow rate and flow rate.It shows that water replenishment is a powerful measure to improve the water quality of Dasha River-water ecological environment.Combined with the calculation results of the ecological base flow of the Dasha River,the amount of water replenishment in different periods of the Dasha River under different water environment requirements was studied.Starting from ensuring the minimum ecological base flow of the Dasha River,the basic ecological water requirements of the Dasha River during the dry season are calculated as1579800,911000,711800,887800,456500,158500 m~3 for each month.These data provide a basis for the ecological supplementation of the Dasha River in the later period,and finally sum up the formation of urban river ecological supplementation simulation and optimization technology plan.