Study On Ecological Discharge Of Dewatering Reach In Lower Reaches Of Diversion Small Hydropower

Diversion type hydropower stations have played a huge role in energy,power generation and flood control and drought resistance,but also greatly changed the natural hydrological situation of the river section.The habitat of living creatures has produced a series of accompanying effects.Therefore,it is of practical significance to study and analyze the ecological flow of dehydrated rivers.Based on the overall conceptual model of the structure and function of the river ecosystem,this paper takes the Houxi River,a tributary of the Daning River in Wuxi County,as the research area,and collects relevant basic data by combing literature,collecting relevant data,and on-site field surveys.The current development status of the power station is summarized and analyzed.The lower reaches of the Quanquan Dam in Xihe River is the subject of study.The impact of the diversion type small hydropower on the ecological environment of the river is qualitatively and quantitatively analyzed.We use the River method according to the habitat simulation method and the wet cycle method in the hydraulics method.River 2D and related hydraulic formulas are used to calculate and simulate the hydrodynamics and effective fish habitats of the study section respectively,so as to determine the ecological flow of the dehydration section of the downstream of the diversion type small hydropower,and provide ecological restoration for the dehydration section.in accordance with.The research conclusions of this article are mainly the following aspects:(1)After the construction of the diversion type hydropower station,a dehydration section will be formed between the water-retaining building and the factory building.If a certain ecological flow is not guaranteed,it will cause the river’s hydrology,biology,water quality,river geomorphology and other ecological environments.Impact,causing damage to river ecosystems.(2)This article selects the local peltfish as the target fish,and through the literature query,the suitability curve of the water depth velocity of the target fish during the breeding period is determined.According to the simulation results,the relationship curve between flow and effective habitat area is clarified.The research shows that with the increase of flow,the effective habitat area of the target fish increases first and then decreases.When the flow is 15m3/s,the effective habitat area is the largest.(3)It is clarified that the spawning grounds of Schizothorax prenanti are generally in the shoal area,and according to the research of relevant experts,combined with the simulation of the depth and velocity data of each flow,the river is divided into anhydrous,shallow,shallow,deep,deep Based on the patch type,the pond area and the gentle current,slower current,more rapid current,and rapid current area,using the water depth velocity diversity index,clarified that the habitat water depth velocity diversity of the study river reaches the maximum when the flow is 17.5m3/s.(4)The wet flow method in the hydraulics method was used to preliminarily determine the ecological flow of the non-target fish during the breeding period is 3.13m3/s.Combining the relationship curve between discharge and habitat area and the diversity curve of habitat water depth-velocity,the ecological flow of Schizothorax prenanti in the study period was determined to be 17.5m3/s.With reference to previous studies,the minimum flow velocity required for fish in water-reduced rivers is 0.3 m/s,and the minimum average water depth is 0.5 m.The ecological flow of 3.13m3/s determined by the wet cycle method was simulated using a hydrodynamic model,and the results were compared with the 5m3/s corresponding to the first inflection point of the habitat depth-velocity diversity curve.The ecological flow of split-bellied fish during the breeding period is 5m3/s.Based on the above research and analysis,it provides a basis for the ecological restoration of the river reach.Set a certain discharge flow downstream of dams and other water conservancy projects to ensure the survival and reproduction of target species in the river reach.