| Flood disaster is one of the most frequent natural disasters in the world today,and flood risk assessment is the basis of flood risk management.The HunTai Flood Protection Area is located in Liaoning Province.It is composed of a narrow area between the left bank of the Hunhe River and the right bank of the Taizi River.The area is about 300 km~2.The purpose of this paper is to establish a method framework for evaluating the flood risk in the study area due to the typical flood damage.Firstly,by building a two-dimensional numerical model of flooding,the spatial and temporal evolution process of dike-break flood in the study area was simulated and analyzed.Secondly,based on the information of flood submergence,the flood damage loss in the study area was estimated.Finally,taking grids as research objects and considering the actual situation,a risk evaluation index system was established;through the level difference maximization method(LDMM),the subjective weights of the indices calculated by the AHP and the objective weights of the indices calculated by the entropy weight method were combined;and by using the K-Means clustering algorithm to perform a cluster analysis on the comprehensive scores of the evaluation objects,the risk situation of a typical dyke-breaking flooding was obtained.The main research content of the paper includes the following aspects:(1)Analysis of the current status of flood disaster risk assessment research.This paper summarized research results of flood disaster risk assessment,flood element analysis techniques at home and abroad comprehensively,and compared the advantages and disadvantages of different flood disaster risk assessment methods.Based on the analysis of relevant research,the research framework of this paper is proposed.(2)Building two-dimensional numerical simulation of dyke flooding in the study area.Based on the terrain data,embankment data and land use data of the study area,four typical breaches and their combinations were selected.When the flow processes of different recurrence periods occurred in each breach,the two-dimensional numerical model was constructed by using the HEC-RAS software,can help obtain information on the maximum inundation range,maximum inundation depth,inundation duration,and flood arrival time of the study area under different breaches and different recurrence periods.(3)Estimation of damage caused by dike-breaking flood damage in the study area.Flood disaster losses include economic losses and population losses.And,economic losses can be divided into direct economic losses and indirect economic losses.This article estimates the direct economic losses caused by floods according to the loss rates of different property categories under different submerged water depths.20%of the direct economic loss was used to estimates the indirect economic loss of the flood.According to people's different understanding of floods,Dekay&MaClelland method was used to estimate the population loss in the study area under different breaches situations.(4)Risk assessment of dyke-break flood disaster based on indicator system.Taking the grid of 100*100m~2 as the minimum evaluation unit(evaluation object),considering the characteristics of flood disasters in the study area,and referring to other research results,the index system of risk assessment was constructed from three aspects:disaster-causing factor,disaster-preventing environment and disaster-bearing body.Taking the maximum difference of evaluation objects as the objective function,the weights of the indices calculated by the AHP and the weights of the indices calculated by the entropy weight method were combined through the LDMM.And by using K-Means clustering algorithm to perform a cluster analysis on the comprehensive scores of the evaluation objects,can obtain the risk situation of the study area finally.As examples,the paper evaluates the flood risk of the study area under the process of breach flow in the case of 20-years,50-years and 100-years for combination of Chi Tuozi and Majiapuzi. |
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