【作者】 李伟；

【导师】 李怡静； 李德龙；

【作者基本信息】 南昌大学 ， 水利工程（专业学位）， 2022， 硕士

【摘要】 近年来,极端降雨频发导致的大型洪水灾害对城市发展建设造成了极为恶劣的影响。在工程防洪水平无法显著提升的现状下,非工程措施研究已经成为目前国家防洪减灾工作开展的重要方向,其中洪水风险评估区划是近年来一种成果显著,实用性强且极具代表性的非工程措施。以往国内外洪水风险评估区划研究中,评估指标的选择较为单一且针对性不强、指标权重设置不合理,同时评估多按照空间跨度较大的行政区划确定评估单元导致成果精准性不高且违背了风险分布的客观规律。针对以上问题,本文以大余县城区重点防洪保护区为研究区域开展洪水风险评估与区划的研究,主要工作以及结论如下:(1)基于MIKE21 FM平台建立二维水动力模型对不同频率(20年、50年、100年)洪水演进过程进行模拟,提取淹没水深、淹没历时以及洪水流速等精确的洪水风险要素作为风险评估体系中的危险性指标。经过模型验证与成果检验表明,所建模型合理,计算成果可信度高,可为后续评估提供一定支持。(2)针对以往研究中评估指标选择较为单一和指标权重设置不合理的问题,本文在综合考虑研究区域历史洪水、下垫面以及人口经济分布的基础上,以淹没水深、洪水流速以及淹没历时等水力要素作为危险性指标,以高程、坡度、植被等下垫面要素作为敏感性指标,以人口、GDP、耕地及弱势人群等社会经济要素作为暴露性指标。通过层次分析法以及熵权法分别计算各指标的主观权重和客观权重,在此基础上使用级差最大值法计算组合权重得出较为合理的主客观权重,最终建立了一种指标丰富,权重合理的洪水风险评估体系。(3)针对以往评估单元过大的问题,本文基于GIS平台,以20m×20m栅格作为基本评估单元并对人口,经济等指标使用反距离权重插值法进行插值计算,经过评估指标的量化计算、标准化处理、栅格化处理以及栅格加权计算等工作,得到区域洪水风险评估成果。按照自然断点法将其分为五级,得到的洪水风险区划图可以精准体现不同洪水频率下各地洪水风险的差异性,这对于大余县政府合理制定分洪决策、国土规划以及灾时转移等具有重要的指导意义。更多还原

【Abstract】 In recent years,large-scale flood disasters caused by frequent extreme rainfall have had an extremely bad impact on the development of social modernization.Under the current situation that the level of engineering flood control cannot be significantly improved,the research on non-engineering measures has become an important direction for the current national flood control and disaster reduction work.Among them,flood risk assessment and zoning is a method with remarkable achievements,strong practicability and representativeness in recent years.non-engineering measures.In the past research on flood risk assessment zoning at home and abroad,the selection of assessment indicators was relatively single and not pertinent,and the setting of index weights was unreasonable.The objective law of risk distribution.In response to the above problems,this paper takes the key flood control protection areas of Dayu County as the research area to carry out research on flood risk assessment and zoning.The main work and results are as follows:(1)Establish a two-dimensional hydrodynamic model based on the MIKE21 FM platform to simulate the evolution process of floods at different frequencies(20 years,50 years,100 years),and extract accurate flood risk factors such as submerged water depth,submerged duration and flood velocity as a risk assessment system risk indicators in The model verification and result test show that the built model is reasonable and the calculation results are highly credible,which can provide certain support for subsequent evaluation.(2)In view of the problems of single evaluation index selection and unreasonable index weight setting in previous studies,this paper comprehensively considers the historical flood,underlying surface and population and economic distribution in the study area,and uses the submerged water depth,flood velocity and submerged duration,etc.Hydraulic factors are used as risk indicators,underlying surface factors such as elevation,slope,and vegetation are used as sensitive indicators,and socioeconomic factors such as population,GDP,cultivated land,and vulnerable populations are used as exposure indicators.The subjective weight and objective weight of each index are calculated by the AHP and the entropy weight method respectively.On this basis,the combined weight is calculated by the maximum difference method to obtain a more reasonable subjective and objective weight.Finally,a kind of index rich and reasonable weight is established.Flood risk assessment system.(3)In view of the problem that the evaluation unit is too large in the past,this paper is based on the GIS platform,and uses the 20m20 m grid as the basic evaluation unit and uses the inverse distance weight interpolation method to interpolate the population,economy and other indicators.After the quantitative calculation and standardization of the evaluation indicators,grid processing and grid weighting calculation,etc.,to obtain regional flood risk assessment results.According to the natural breakpoint method,it is divided into five levels,and the obtained flood risk zoning map can accurately reflect the difference of flood risk in different places under different flood frequencies,which is useful for the Dayu County Government to make reasonable flood diversion decisions,land planning and disaster transfer.has important guiding significance.更多还原