Study On Flood Disaster Risk And Resilience Assessment In Yangtze River Delta

In the context of climate change,flood disaster risk has become one of the most important issues for the sustainable development of the Yangtze River Delta in China.The resilience theory provides a new perspective and theoretical system for regional response to disaster risk and improve the ability of disaster prevention and mitigation.This paper has formed a theoretical framework for regional flood disaster risk assessment and a theoretical framework for flood disaster resilience assessment;an assessment method system based on Multi-criteria Decision Making(MCDM),nonadditive non-linear Choquet integration and other methods is constructed.Based on the above theoretical framework and method system,the flood disaster risk and resilience level in the Yangtze River Delta are assessed,and the key influencing factors are identified.Finally,based on the evaluation process and results,the framework of regional flood disaster risk management and resilience construction decision support system is designed.Firstly,taking the regional flood disaster as the research object,this paper has formed a theoretical framework of regional flood disaster risk assessment,including five subsystems of hazard,exposure,vulnerability,emergency and recovery capabilities,disaster loss,and 19 secondary indicators.Through the above theoretical framework and empirical research,the flood disaster risk status and key influencing factors of different administrative units in the Yangtze River Delta are obtained.The research results can provide scientific reference for decision-making of regional flood disaster risk management.Secondly,guided by the disaster resilience theory,this paper formed a theoretical framework for regional flood disaster resilience assessment,including five dimensions of economic,social,infrastructure,environmental and institutional resilience,21 secondary variables and 49 specific indicators.The theoretical framework was applied to the empirical evaluation of the Yangtze River Delta to test the operability,rationality and data availability.Thirdly,an evaluation method system based on MCDM and Choquet integral with non-additive and non-linear,etc.is constructed.The method system combines the advantages of MCDM method,Choquet integral and entropy weight method,and solves the problem of regional disaster risk and resilience assessment and ranking under the condition of uncertainty,indicator interaction and considering the preferences of decision makers.Finally,based on the above-mentioned assessment theoretical framework and method system,the empirical evaluations are carried out,and the main conclusions are as follows:(1)The results of flood disaster risk assessment in the Yangtze River Delta show that the flood disaster risk in Jiangsu Province and Anhui Province is relatively high,while the flood disaster risk in Shanghai city and Zhejiang Province is relatively low.Sensitivity analysis results show that the flood disaster risk level in the Yangtze River Delta region is more sensitive to agricultural factors(crop sown area ratio,crop disasteraffected area),population density,drainage density,the number of medical and health institutions,etc.;TOPSIS method has the least influence on the weight changes,and the evaluation results also remain stable.From the results of scenario analysis,in terms of hazard,exposure,vulnerability,and disaster loss,Jiangsu Province has the highest flood disaster risk;from the perspective of emergency and recovery capabilities,the flood disaster risk in Anhui Province is the highest;the flood disaster risks of Shanghai city and Zhejiang Province have always ranked third and fourth.(2)Based on the Choquet integral flood disaster risk assessment model considering the interaction between indicators and the preference of decision makers,the results show that: Firstly,after setting the relevant parameters considering the preference of decision-makers,the flood disaster risk in Anhui Province is the largest,followed by Zhejiang and Jiangsu Province,and Shanghai is the lowest.Secondly,by quantifying and reducing the interaction of indicators,the score gaps of different administrative units have been reduced.The largest gap between Anhui Province and Shanghai is 5.6,followed by the gap between Anhui Province and Jiangsu Province and Zhejiang Province is 4.7 and 4.1 respectively,and the smallest gap between Zhejiang Province and Jiangsu Province is 0.6.(3)The assessment results of temporal and spatial dimensions of resilience and key factors identification of flood disasters in the Yangtze River Delta show that: The resilience level of flood disaster in Shanghai has fluctuated little over the years,and the resilience level of flood disaster in Jiangsu,Zhejiang and Anhui Province have shown an upward trend year by year;from 2006 to 2019,the resilience level of flood disaster in Shanghai was the highest,followed by Jiangsu Province,and lower in Zhejiang Province and Anhui Province.The main influencing factors of flood disaster resilience include economic development,employment situation,demographic characteristics,food security,response and recovery capacity,ecological environment protection,grassroots government service,and so on.(4)Based on the above evaluation process and results,this paper designs the framework of regional flood disaster risk management and resilience construction decision support system,and puts forward countermeasures and suggestions to improve the level of flood disaster risk management and resilience construction in the Yangtze River Delta from the aspects of planning guidance,capacity-building,regional linkage,introduction of new ideas,overall planning of urban-rural integration,grasping the “key factors”,focusing on differentiated development and strengthening planning guidance.