类型与等级双重限定下的雨涝韧性评估与优化

Assessment and Optimization of Stormwater Resilience Via Classification and Grading

基于定性与定量相结合的研究视角,将类型与等级双重限定的方法应用于城市雨涝韧性评估。立足于城市建成环境与雨涝韧性机理的耦合关系,构建“雨涝灾害-建成环境-韧性属性”关联逻辑下的评价指标体系。以天津市中心城区为例,分别运用K-means聚类算法、ArcGIS空间加权计算完成类型划定与等级划分,并总结分类定级结果,将研究区域划分为重点提升单元、专项整治单元、常态维稳单元三级提升区域。结合评估结果与研究区实际问题,从雨水调蓄、应急救援等方面提出城市雨涝韧性提升的时序安排与优化导引。

Urbanization and climate change have increased the frequency of urban rainstorm and flood events.Although urban flooding is inevitable under extreme climatic conditions,it is critical to enhance the resilience of cities to minimize disaster losses.Existing qualitative assessments of flood resilience emphasize theoretical and conceptual factors rather than actual policies and practices.Quantitative assessments tend to reduce the complexity of flood management to finite variables,which prevents insight or understanding of the phenomenon.The assessment of stormwater resilience via classification and grading provides a qualitative and quantitative perspective.Such an assessment not only contributes to the analysis of the current urban rainwater challenges,but also provides a deep understanding and interpretation of possible causes.It enables development of targeted resilience enhancement strategies for the study area.Based on a combination of qualitative and quantitative studies,the urban stormwater resilience was analyzed via classification and grading.Based on the combination of built environment and flood resilience mechanism,an evaluation index was developed.Factors such as flood disaster,built environment,and resilience were utilized to develop 18 indices under the target layers of resistance and recovery.Flood resilience in the central urban area of Tianjin was divided into four classes high resistance-high recovery(HS-HC)using the K-means clustering algorithm.Subsequently,flood resilience in this study area was graded into five categories(Ⅰ~Ⅴ)via spatial weighting using the ArcGIS(version10.4).According to the summary of classification and grading,Grades Ⅰ-Ⅲ associated with low resistance-low recovery(LS-LC),Grades Ⅰ-Ⅱ associated with low resistance-high recovery(LS-HC),and Grade Ⅱ involving high resistance-low recovery(HS-LC)were determined as level-1 improvement zones.Grades Ⅲ-Ⅴ associated with(HS-LC)and Grades Ⅲ-Ⅴ involving(LS-HC)were determined as level-2 improvement zones.Grades Ⅲ-Ⅴ including(HS-HC)represented the level-3 improvement zone.These three levels of improvement zones corresponded to key improvement units,special governance units,and normal stability maintenance unit,respectively.Finally,the scheduling and optimization guidance for improvement of urban stormwater resilience improvement were proposed by combining with evaluation and practical challenges in the study area.The goal for level-1 improvement zone was flood storage enhancement and emergency risk avoidance.The goal for level-2 improvement zone was special complementation and overall improvement.The goal of level-3 improvement zone was rainwater storage and resilience.Determining the resilience improvement of different units can provide specific,scientific and effective theoretical guidance for optimized urban construction.