Ecological Risk Assessment Of Flood Disaster In Tumen River Basin

Ecological risk assessment of flood disaster takes flood disaster as risk source and ecosystem as risk receptor,which reflects the relationship between flood disaster and ecological environment.Tumen River Basin has dense inland river network and numerous water systems.Affected by many factors,frequent floods occurred in recent years,which not only had a great impact on the lives of local residents,but also caused some losses to the local ecosystem.In this paper,the ecological evaluation model of flood disaster in Tumen River Basin is constructed from three aspects of flood disaster risk,ecological vulnerability and social-economic vulnerability,which provides the basis for disaster prevention and mitigation and maintaining ecosystem stability in the study area.In this paper,rainfall is selected as the disaster causing factor,and elevation,topographic relief,river buffer zone,slope,river network density,land use type and soil type are selected as the disaster inducing environment to calculate the flood risk of Tumen River Basin.Analytic hierarchy process,information method and random forest algorithm are used to predict the flood hazard distribution map of Tumen River Basin.The flood disaster points calculated by the information method account for 70%of the level V risk area,and the accuracy of the three methods is the highest.Therefore,the flood disaster risk layer calculated by the information method is selected for the follow-up study.According to the analysis of the calculation results,the areas with high risk of flood disaster in Tumen River Basin are mainly located in the middle and south of Jingxin Town in Hunchun City,the north of Banshi Town,the middle and south of Liangshui Town in Tumen City,the border between the middle of Longjing City and the South of Yanji City,and the two sides of neigaya River Basin in Wangqing County.In the Tumen River Basin,the risk level in the East,West and north of Wangqing County,the north of Hunchun City and the south of Longshi City is low.According to the distribution types of ecosystem in Tumen River Basin,fragstats4.2 software was used as the main data processing tool,and patch density,average patch area,maximum patch index,boundary density,reciprocal of perimeter area score dimension and landscape separation were used as evaluation indexes.The relative weight of each index was calculated by analytic hierarchy process,and then the ecological types were calculated based on arcmap10.2 platform Vulnerability index.It can be seen from the calculation that the ecological vulnerability of most areas in the Tumen River Basin is low,and the areas with high ecological vulnerability are mainly distributed in the middle and north of Longjing City,the south of Yanji City,the southwest of Hunchun City and the northeast of Helong City.The calculation of social and economic losses is carried out from two aspects of human society and ecological losses.Population density is used to evaluate the economy of human society,and biodiversity and net primary productivity are used to evaluate the ecological loss.The results show that the regions with high social and economic vulnerability in Tumen River are mainly located in the west and northeast of Hunchun City,the middle of Yanji City,and the northeast and southwest of Tumen City.The areas with low social and economic vulnerability are mainly located in the west,northeast and south of the north end of Longjing City,the north central part of Helong city and the north central part of Wangqing County.Finally,the ecological risk assessment model is used to evaluate the ecological risk of flood disaster in Tumen River Basin.The results showed that the proportion of grade Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ and other risk areas were 30%,25%,17%,16%and 12%respectively.The high-risk areas are mainly distributed in the south of Yanji City,the middle and north of Longjing City,the middle of Wangqing County,the east and south of Hunchun City,and the low-risk areas are mainly distributed in the northeast and northwest boundary of Wangqing County,and the critical area with Hunchun City,the middle and south of Helong City And so on.