Research On The Fine Simulation Of Hydrodynamic Elements In The Process Of River Flood

With the rapid development of urbanization and the rapid change of global climate,the frequency and harm fulness of natural disasters have increased significantly.The mountain flood,dam break flood and urban inundation caused by extreme rainstorm are the most significant disasters.Based on the sudden and uncontrollable characteristics of flood disasters,the accurate simulation of flood process by a stable and efficient numerical model and accurate analysis of hydrodynamic index(water depth,velocity and flow,etc)of flood discharge section can provide support basis for predicting flood inundation range and risk assessment,which is of great significance to flood prevention and post disaster emergency evacuation.In this paper,the Gast model,which can describe the terrain accurately,simulate the flood routing process efficiently and stably,and simulate the hydrodynamic factors accurately,is employed to simulate the flood routing process and analyze the relevant hydrodynamic factors.Firstly,the model is applied to simulate the common flood routing process of the Ziwu river section,and the hydrodynamic indexes of the river section under different working conditions are studied.Then,the dam break flood routing process under the rare flood in the downstream channel of Jinping Hydropower Station is simulated,the risk assessment under different working conditions is carried out by analyzing the hydrodynamic indexes of the section,and the risk avoidance transfer road map is drawn.Finally,the model is applied to the simulation of practical engineering.By analyzing the hydrodynamic indexes of river section under different working conditions,the adaptive drifting process of river is simulated to obtain the optimal drifting scheme,Different schemes prove that the model can be widely applied to flood simulation in different situations.It can not only stably and accurately simulate the hydrodynamic index of river section to calculate the inundation range and risk assessment under different working conditions,but also be applied to the simulation of practical projects to provide technical support for the economic development of river.The main conclusions are as follows:1.The flood routing process of river channel is simulated by GAST model,and the model is verified by measured data,the results show that the model has high accuracy,and the calculation efficiency is greatly improved by using graphics card acceleration technology;2.By simulating and analyzing the hydrodynamic indexes of the common flood routing process of the river channel in Ziwu reach.It is concluded that the inundation range is significantly reduced after river regulation:when the river channel is dredged for 6m,10m and 20m in 10-year and 20-year flood discharge,the inundation area of drainage channel and farmland is reduced by 2960m2,3420m2,2280m2 and 1890m2,3760m2 and 2560m2,respectively;3.By simulating the hydrodynamic index of the rare dam break flood in the downstream of Jinping Hydropower Station.It is concluded that:The water depth of the river section increases with time until the maximum water depth appears,then decreases slowly and tends to be stable gradually;The starting velocity is directly proportional to the arrival time of the flood front,and the arrival time of flood peak is directly proportional to the distance from the breach;According to the risk assessment and analysis,the route map of flood avoidance and transfer is drawn;4.By simulating the process of the actual adaptive drifting project of the river channel and analyzing the hydrodynamic indexes,and comprehensively considering the economic benefits,it is concluded that the most suitable drifting condition is when the river channel is dredged for 6m.its flow required for drifting is only 4～7m3/s,which is 54～56m3/s less than that of the natural river channel,2～5m3/s less than that of 10m river dredging,and 13～16m3/s less than that of 20m river dredging.