Study On Flood Regulation Of Cascade Development River

China is a country with frequent and extensive flood disasters,which cause huge loss of life and property every year.According to statistics,about one third of the cultivated land,two fifths of the population and one quarter of the industrial and agricultural production in China are often threatened by floods and cause huge losses.Flood disasters usually show seasonal,regional and repeatable characteristics.In China,flood disasters are generally less in the West and more in the East,less in the inland and more in the coastal areas,more in May to October and less in November to April.Oujiang River Basin,which originates from the junction of Longquan and Qingyuan in Zhejiang Province,is located in the southeast coastal area of China.It runs through the whole mountain area of southern Zhejiang from west to East.The terrain of "nine mountains,half water and half farmland" causes the characteristics of waterlogging.The research object of this paper is the daxihaikou section of the Oujiang River Basin,where the flood disasters occur frequently,causing huge economic losses to the coastal residents and seriously threatening Haikou town Life safety of residents.Therefore,with Haikou town as the key research area and two hydropower stations in the upper and lower reaches of Haikou town as the boundary conditions,the hydrodynamic model is established,and the reasonable dispatching scheme between the two hydropower stations is sought through the evolution simulation analysis of the flood in the interval.Based on the special research project of flood control capacity improvement measures in Haikou Town,Qingtian County,this paper uses HEC-RAS model to carry out research on the following aspects:1.Based on the principle of scientificity and accuracy of flood evolution simulation process,HEC-RAS model is selected as the calculation tool,and the principle of HEC-RAS model is explained in detail.1.In this paper,the intelligent unmanned underwater topographic survey technology is used to densify the large section of the key river section where Haikou town is located.Wuliting hydropower station is the upper boundary in the upstream and Xiong hydropower station is the lower boundary in the downstream.2.The model parameters such as expansion coefficient,contraction coefficient,boundary condition,roughness and channel gradient are analyzed and determined,and the model parameters are calibrated by the measured flood data.3.In order to ensure the reliability of numerical simulation of flood evolution,the hydrological data of Oujiang River Basin are collected,and the peak discharge of Haikou section is analyzed and calculated according to the reasoning formula method of Zhejiang Province.Using the hydrodynamic model to simulate the flood evolution,the simulation results show that when there is a five-year return period flood in Haikou section,the water level of the section with stake number of 7 + 359.77 is 32.77 m,and the flow velocity is 1.77m/s;the water level of the left bank is 0.8m,and the water level of the right bank is 0.2m;when there is a ten-year return period flood,the water level of the section with stake number of 7 + 359.77 is 35.42 m,and the flow velocity is 1.74m/s,the water level of the left bank is 3.45 M,and the water level of the right bank is 3.45 M The water level on the bank is 2.67M;when the 20-year flood occurs,the water level is 37.6m,the flow rate is 1.76m/s,the water level on the left bank is 5.63 m,and the water level on the right bank is 4.85 M.The reach of Haikou town cannot meet the flood control standard of once in five years.Under the condition of once-in-a-decade and once-in-20-year floods,Haikou town is seriously flooded,and guankeng village,chenzhuan village,Shacun village and Jiefu village along the coast suffer from different degrees of flood disasters.4.Based on the calculation of flood control operation,the flood control operation principles of Wuliting water control project and Waixiong water control project are put forward based on the maximum peak cutting principle,which provides scientific basis for the cascade operation of the two hydropower stations.