Research On Flood Risk Evaluation In The Middle Reaches Of The Yangtze River Based On ESF-AHP

Flood and waterlogging are the natural disasters that cause the greatest loss of human property and life in history.Flood disasters at different times and regions are usually caused by different leading factors.Flood disaster risk mapping in large regions is an important issue to be solved urgently in the task of flood disaster prevention.This paper mainly focuses on the risk assessment of flood and waterlogging disasters in the middle reaches of the Yangtze River under the severe shortage of sample data of flooding and waterlogging disasters.The study proposes a two-stage model(ESF-AHP)for regional flood risk assessment—risk assessment of river network based on Spatially Filtered Poisson regression(ESFPS)and regional risk assessment based on analytic hierarchy process(AHP).The research content includes the following four points:1.Risk assessment of river network based on Eigenvector Spatially Filtered Poisson regression(ESFPS)is proposed.Prove the spatial autocorrelation of flood warning events,and then use Poisson regression to model the risk of flood disasters based on spatial filtering algorithm,using multi-source heterogeneous hydrological report data and risk factor data.ESFPS mainly includes five steps of constructing spatial weight matrix,spatial autocorrelation test,feature vector decomposition,feature vector stepwise regression and weight coefficient calculation.The Pseudo R Squared of the model reached 0.78,39.29% higher than traditional Poisson regression model.The results show that continuous heavy rainfall and vegetation profiles were the main culprits of the flood disaster in the region and the risks are higher in the upper reaches of the Han River,the Poyang Lake area,the Juzhang River and the Dongting Lake area.2.The study proposes a regional risk assessment method combining ESFPS and AHP.In order to overcome the subjectivity of experts' weight determination,using the ranked weights of factors obtained by the ESFPS model combined with the analytic hierarchy process,the risk and vulnerability analysis of the middle reaches of the Yangtze River city cluster from the prefecture and county scales,and finally the middle reaches of the Yangtze River city Distribution map of flood disaster risk index of the group.It mainly includes four steps: coefficient mapping,test of discriminant matrix consistency,weight coefficient calculation,weighted summation.The results show that Huaihua,Tujia and Miao Autonomous Prefecture and Loudi City in Hunan Province,Enshi Autonomous Prefecture,Yichang City,and Jingzhou City in Hubei Province are facing greater flood risk.The risk of flood disasters is mainly concentrated in the northwest of Hunan Province and the west of Hubei Province.3.A system of monitoring flood and waterlogging disaster and risk assessment was constructed,which mainly used GIS-related technologies to display multi-source heterogeneous data related to flooding.The system displays the hydrological report,meteorological information and historical statistics in real time and the results of river network risk assessment in a friendly form of visualization.