Reservoir Capacity Prediction And Flood Inundation Simulation Based On 3D Optimization Model

Reservoir is one of the engineering measures of flood control widely adopted in our country,it plays an important role in regulating area surface flow and land water cycle,our country has a long history of reservoirs,restricted by technology,economy and environmental conditions at that time,these reservoirs and levees project in different degrees have certain security risks,if full reservoir capacity operation has a certain risk.Therefore,in the flood season,especially in the coastal typhoon rainstorm season,will involve the sluice discharge and downstream flood risk.Therefore,it is particularly important to effectively predict the variation of reservoir capacity and the influence range of potential flood disaster caused by discharge during the rainstorm season,which is an important theoretical basis for disaster prevention and reduction decisions.This paper takes Shanmei Reservoir in Quanzhou City,Fujian Province,China as the research object,and proposes a reservoir capacity prediction model based on the improved three-dimensional trapezoidal Tank model,which can quickly predict the future reservoir capacity according to the rainfall conditions.Through the field verification during the typhoon rainstorm season,the model shows a good effect.Then,HEC-RAS was used to establish the reservoir discharge evolution model,simulate the discharge conditions of different superstandard flood,and analyze the flood characteristics in the evolution process and its impact on the upstream reservoir,downstream coastal building facilities and downstream cities and towns.Finally,based on the information of flood inundation,the loss of life and property is estimated in the study area.The main research contents of this paper are as follows:(1)The generalized trapezoidal Tank model is developed,and the trapezoidal Tank model is optimized and improved in combination with the hydrological and topographic characteristics of the research object.Finally,the three-dimensional irregular tank prediction model for large reservoirs is proposed,and a simple,fast and low-cost prediction method for the changes of reservoir storage capacity affected by rainfall is obtained.The practical case shows the feasibility of this model.Compared with the trapezoidal Tank model,the prediction accuracy of the improved 3D model is improved by 2.6-13.45%.(2)The HEC-RAS two-dimensional model was constructed from seven aspects,including initial working setting,reservoir characteristic setting,dam and spillway parameter setting,roughness setting,computational topography generation,boundary condition and initial condition setting,and the flood evolution process was simulated under three conditions,one in 20 years,one in 50 years and one in 100 years,so as to obtain accurate water situation data of each location downstream.The results show that the maximum submerged depth of the once-in-20 years flood is 22 meters,the maximum velocity of the flood is 17.8m/s,the submerged area is 20.91km2,and 20 villages are submerged.The maximum inundation depth was 24 meters,the maximum flood velocity was 21.517.8m/s,the inundation area was24.11km2,and 30 villages were inundated.The maximum inundation depth was 25 meters,the maximum flood velocity was 22.8m/s,the inundation area was 27.38km2,and 34 villages were inundated.(3)The HEC-RAS model was used to obtain the flood inundation results and determine the regions with different risk levels.Then,by selecting the main influencing factors(population at risk,severity of flood,warning time and understanding degree of population at risk to severity of dam break)and secondary influencing factors(composition of population at risk,occurrence time of dam break,distance from dam,height of dam,reservoir capacity,downstream terrain and occurrence time of dam break)of the flood loss in Shanmei Reservoir,To determine the extent to which these factors contribute to mortality.Formulate the calculation method of flood loss of life and property in line with the actual situation of the area.The results show that the loss of life in a 20-year flood event is 8659,that in a 50-year flood event is 9763,and that in a 100-year flood event is 10662.