Dam Break Simulation And Risk Analysis Of Hongqi Reservoir

China is one of the countries with the longest history of dam construction,especially since the founding of new China,China has carried out large-scale water conservancy project construction.However,due to the influence of many factors such as long-term disrepair,dam break accidents often occur.Therefore,once the dam burst,numerical simulation will be very necessary for people’s lives.In this paper,Hongqi reservoir in Qianshan City,Anhui Province is taken as the research object,and the dam break simulation and risk analysis are carried out.The research results can provide technical reference for Hongqi reservoir to formulate reservoir dam flood control and disaster reduction work plan and emergency plan for reservoir dam safety management,and further guide the study of earth rock dam break.The main contents of this paper include:（1）Using Arc GIS to embed and cut the downloaded DEM,the DEM in the study area can be obtained.Using the linear reservoir assumption,the reservoir is completely controlled by the reservoir capacity curve.Through the study of the relationship between land cover and roughness,the roughness value of the study area is determined.Both unstructured grid and structured grid are used in mesh generation.Using the whole model method,the upstream boundary condition is the check flood inflow process of Hongqi reservoir with a return period of 2000 years,and the downstream boundary condition is set as the free outflow boundary.Different positions and shapes of the breach are worked out,and three kinds of dam break conditions are determined.The calculation step length of the model is 3 s,which satisfies the condition of the stability of Coulomb.The total momentum equation is selected as the model calculation method.（2）The discharge hydrograph,local flow pattern downstream of the breach,flood velocity distribution and flood submergence depth distribution under three dam break conditions are simulated.It is found that the larger the instantaneous breach size is,the greater the initial discharge is,and the faster the initial discharge hydrograph changes,while the smaller the breach size,the slower the change of the discharge hydrograph.The flow velocity and flow direction of the local flow pattern in the downstream of the breach show that the simulation results are reasonable.（3）Based on the analysis of the simulation results,the risk map of inundation depth is drawn and the flood control transfer scheme is proposed.Then,the dam break probability analysis and the life loss assessment of Hongqi reservoir are carried out.The probability of dam break caused by flood is 7.158×10^-4per year.It is found that the longer the alarm time is,the lower the life loss and the severity coefficient of life loss are.When the alarm time is1 hour,the life loss is obviously reduced.When there is no alarm,the life loss reaches 210people,and the life loss is 0 when the alarm time is 3.5 hours.