Study On Risk Assessment Of Heavy Rain And Flood In Dazhan Reservoir Basin Based On One-dimensional Coupled Hydrodynamic Model

In recent years,affected by climate warming,heat island effect and other factors,extreme rainfall events have increased,and floods caused by heavy rains have also increased in all parts of the country.Dazhan Reservoir Basin in Zhangqiu City,Shandong Province,is a high-incidence area of heavy rains and floods.The floods have caused serious losses to local social economy and endangered the lives of residents.Therefore,a study on assessment of heavy rains and floods has been carried out to reduce property damage of residents.It is of great significance to protect the lives and safety of residents.In this paper,Dazhan Reservoir Basin is taken as the research area,and flood risk assessment is studied by means of field investigation,data collection,theoretical analysis and computer simulation.The main contents of this paper are as follows:(1)Study on one-dimensional hydrodynamic coupling model of storm flood.Mike software is used to construct a two-dimensional hydrodynamic coupling model of rainstorm and flood.Combining the measured data with the survey data,the boundary conditions of the model,the roughness of river channel and the coefficient of land use are determined.(2)Study on Simulation of risk factors of typical frequency rainstorm flood.Three typical frequency storm(P=1%,0.2%.0.1%)flood risk factors were simulated by using a two-dimensional hydrodynamic coupled model of rainstorm and flood,and the impact of flood risk factors on the study area was analyzed.The conclusions are as follows:1)With the increase of rainstorm recurrence period,the depth and extent of flood inundation increase.The maximum submerged depth of the three frequency floods is 1.95m.4.8m and 5.6m.and the maximum submerged area is 0.02 km2,2.01 km2 and 2.57 km2,respectively.The disaster-affected area has increased from Shixia Village to Duozhuang Village.Shixia Village,Beiming Village and downstream areas.2)In the three main disaster areas of Shixia Village.Duozhuang Village and Beiming Village,compared with Shixia Village.Duozhuang Village and Beiming Village have small disaster area but serious disaster degree,which should be paid attention to.The maximum submerged water depth and submerged area of the three disaster areas are 1.2m,2.6m,2.8m and 0.32km2,0.16km2 and 0.15km2,respectively.(3)Rainstorm flood risk assessment.Based on the simulation results of typical frequency storm flood risk factors and the regional socio-economic situation,the flood risk and vulnerability factors are determined.Based on the flood risk factors and the relationship between population and economy in the study area,a flood risk assessment model is constructed and the flood risk assessment is carried out.The comprehensive risk values of three typical frequencies of torrential rain and flood are 2.184-9.191.2.184-40 and 2.18-44.82.respectively.The economic losses of three frequencies(P=1%,0.2%,0.1%)are 16.34 million yuan,3789.8 million yuan and 4116.77million yuan respectively.The population losses decrease with the increase of warning time,and when the warning time is more than 4 hours,the population losses are 0.