The Evolution Mechanism And Governance Countermeasures Of Urban Waterlogging Disaster Under The Framework Of Disaster Risk Reduction Based Resilience

In recent years,there have been frequent disasters around the world.In 2020,the threat of climate disasters was identified as the year’s biggest risk.The rapid urbanization process that China has experienced in recent decades makes it face more complex disaster threats.The continuous occurrence of rain and flood catastrophe has attracted great attention from the governance and people from all walks of life.Since2016,documents and actions on "adapting cities to climate change" and "strengthening waterlogging management" have been continuously issued in China.The research and exploration of the theory and practice of rain and flood disaster goverment has also become a hot topic of real-time attention in the academic community.In the field of disaster social science,theoretical exploration of resilience,vulnerability,adaptation and mitigation has been deepening.Under the background of disaster risk management exploration,the research on flood disaster reduction with city as the research boundary is constantly deepening.At present,the contradiction between the practical needs of "one city,one policy" and the difficult implementation of advanced disaster goverment propositions needs to be solved urgently.So,to research the evolution mechanism of waterlogging disaster process related to the specific natural and social background of a city,under the framework of social ecological resilience,in order to establish an effective waterlogging disaster reduction management system and management plan,has important practical and theoretical significance.With the aid of bibliometric analysis tools,multi-layer complex network model and system dynamics theory and tools,the method of combining qualitative system evaluation and quantitative case analysis was used to carry out the research from the process of problem raising-document tracing-theory construction-risk assessment-governance response for urban disaster risk reduction,in this dissertation.The theoretical and technical frontiers in the field were explored through the research trends of urban waterlogging disaster reduction,which laid a foundation for the follow-up study of urban waterlogging disaster reduction programs.Through the analysis of disaster region,division and social attribute,the boundary of rain flood disaster research with city as the disaster bearing body was discussed.Based on the research process of disaster risk governance theory,the connotation of disaster risk reduction was analyzed,and the research scope and path of urban rain and flood disaster risk reduction were clarified.Based on the analysis of disaster structure of urban man-land system under the framework of evolutionary resilience,the mechanism of resilience waterlogging was determined that urban drainage subsystem was the main body of disaster response.Through the process of urban drainage system waterlogging risk index identification,system construction,system and network analysis,SD model construction and so on,the evolution mechanism of urban waterlogging risk was explored.Taking Tianjin as an example,through the Vensim simulation platform,the urban waterlogging sensitive factors were sorted,simulation scenarios were set,and the evolution trend of waterlogging risk was analyzed.On this basis,combined with the urban development process,current situation and planning,the causes of urban waterlogging were discussed.A four-section waterlogging monitoring and early warning system was constructed by the urban waterlogging classification model based on "three-point method".A specific disaster reduction system was established based on the warning level and for different storm flood scenarios,with the goal of "no ponding for moderate rain,no waterlogging for heavy rain,quick recovery for rainstorm,and fewer casualties if exceeding the standard".The disaster reduction system has action plans in the short,medium and long term,in order to quickly improve the waterlogging response level in the short term and realize the toughness planning of "symbiosis with water" in the long term.This study based on the deepening of Shi Peijun’s disaster system,created a territory-region-watershed interactive urban waterlogging disaster system,and revealed the rain and flood disaster mechanism and multi-risk interaction mechanism in a specific space.And,it contributed to the urban waterlogging risk assessment procedures and methods under the theory of evolutionary resilience,and provided scientific support for the precise management of urban waterlogging risks.In addition,in this study,a hierarchical disaster reduction(emergency)system was constructed with the interactive effects of rain conditions and the characteristics of the disaster-affected area as trigger points to provide a sample for urban waterlogging disaster risk reduction and governance.