Research On Disaster-Adapted Theory And Optimization Strategy Of Urban Spatial Layout Based On Rainstorm Waterlogging Disaster Prevention And Control

China’s urban rapid development and construction have neglected the adaptation to global climate change and the coordination of urban spatial layout,resulting in the disorder of the hydrological cycle and the reduction of the regulation efficiency of the disaster prevention system,which leads to a series of rainstorm waterlogging(Waterlogging for short)problems such as "Viewing the sea inside the city",and the contradiction between waterlogging disaster prevention and urban development is prominent.Therefore,the research on disaster-adapted theory and optimization strategy of urban spatial layout based on waterlogging disaster control is of great significance to promote urban sustainable development.Based on the analysis of scientific trends,basic theoretical research and practical experience of domestic and foreign research in related fields,the shortcomings of existing research and prediction of future research trends were summarized:(1)Most of the techniques and methods related to waterlogging disasters have limitations,such as high data type requirements,difficult calculation or strong subjective dependence;(2)Insufficient attention has been paid to the scale effect and spatial effect of waterlogging disasters,and there is still much research potential on the comprehensive impact of systematic and complex urban spatial layout on waterlogging disasters;(3)The implementation path of improving the disaster adaptability of waterlogging disasters from the technical language and practical perspective of urban spatial planning is insufficient;(4)Finding a way out from the evolution law of urban system and disaster system,and changing from passive disaster defense to active disaster adaptation is one of the development trends of waterlogging disaster prevention research in China.From the perspective of flood disaster prevention,taking the rising characteristic economic groups and representative areas of waterlogging disaster in Min delta as an example,the urban spatial system composed of "scale expansion","land use form" and"functional organization",and the disaster-adaption theory of urban spatial layout were established.Taking the urban spatial system as the starting point and the disasteradaption theory of urban spatial layout as the support point,"how to influence? and"how to optimize?" the two core issues were oriented to build a comprehensive research framework from "macroscopic identification" to "microscopic analysis".Among them,"macro-analysis" is a prerequisite for analyzing and solving the two scientific problems,including "regional spatial cognition" and "regional spatial optimization".The"microscopic analysis" is the core part of the analysis and solution of the two scientific problems,including "urban spatial cognition" and "urban spatial optimization".Firstly,from "regional spatial cognition",the composition of waterlogging risk systems were improved,and the risk identification system of "3 species relationship(disaster-causing factor,disaster-inducing environment,disaster-affected body)-2class characteristics(natural dominant risk,human dominant risk)-20 indicators" were established.GIS multi-criteria evaluation coupled BP neural network algorithm was used to identify the risk of waterlogging disaster.Based on the identification results,the system coupling characteristics,spatial correlation characteristics,and main control factor characteristics of the urbanization process and waterlogging disasters in the Min Delta region were judged.Based on the characteristics,the high-risk areas of waterlogging disasters in the Min Delta region were classified into "Positive-action dominated area","Negative-action dominated area" and "Bidirectional-action area";according to the calculation,the "Bidirectional-action area" generally has the stage characteristics of the transition from lagging urbanization to high urbanization,and the contradiction between urban construction and waterlogging disasters is the most significant,so it is taken as a "typical waterlogging risk zone" for in-depth study.Secondly,from "urban spatial cognition",the disaster characteristics such as density of affected points and depth of waterlogging in "typical waterlogging risk zone" were measured based on big data and BP neural network algorithm;The multi-scale research system consisting of "global-local" research scale and "watershed(or neighborhood)-grid" analysis scale is built to analyze the impact of relevant indicators of urban scale expansion,land use form and functional organization on the waterlogging disasters at different scales,proving that there are scale effects and spatial heterogeneity in the influence of urban spatial layout on the waterlogging disasters;based on the residual distribution law of the calculation results,other important potential influencing factors besides scale,land use and functional indicators were identified,to summarize the comprehensive influence of urban spatial layout on the disaster situation of waterlogging,so as to summarize the comprehensive impact mechanism of urban spatial layout on the waterlogging disasters,and provide a scientific basis for the construction of disaster adaptation and optimization strategy of urban spatial layout.Finally,based on the conclusion of the study of "regional spatial cognition" and the analysis of the current waterlogging disaster prevention practice,the "trade-off game","coordination and connect",and "identification and emphasis" strategies for "regional spatial optimization" were constructed.The aim is to provide a robust system environment for the construction and implementation of disaster-adaption optimization strategies for urban spatial layout.On the premise of system stability in the whole area,based on the findings of "urban spatial cognition" and the dynamic simulation of urban spatial layout features in different rainfall scenarios,combined with the contents of spatial morphology,hydrological characteristics and urban planning principles,the "urban space optimization" strategies of evolutionary adaptation(Threshold division of disaster adaptation),dynamic adaptation(Spatial reconstruction of disaster adaptation)and differential adaptation(zoning guidance of disaster adaptation)were constructed for each core spatial index and each spatial feature combination.The research results will be effectively connected with china’s urban planning system to alleviate the problem of urban development and flood control from the perspective of urban spatial planning.The academic innovation of this study mainly consists of three points:(1)improving the risk identification system of waterlogging disasters,adopting integrated technologies such as multi-source data fusion,GIS application,and machine learning algorithms to explore urban waterlogging disasters,and making up for the limitations of common technical methods;(2)constructing a core urban spatial index system and multi-scale research system affecting waterlogging disasters,and clarifying the law of urban spatial layout on waterlogging disasters;(3)discussing the disaster-adaption optimization strategy of urban spatial layout based on waterlogging disasters prevention with the disciplinary perspective and technical language of urban spatial planning in line with the development trend of disaster adaptation theory and technology,and providing a reference for the transformation and optimization of China’s cities to adapt to waterlogging disasters and sustainable development practices.