基于损失函数的城市洪涝灾害弹性演化规律研究

Research on Evolution of Urban Flood Resilience Based on Loss Function

为了提升城市防洪水平与洪涝灾害恢复能力以及推进以人为核心的新型城镇化战略的目标任务,以潍坊市城区为研究区域,借助基于元胞自动机的CAflood模型获取淹没水深数据,并通过数据挖掘与相似性分析方法直接移植引用城市损失率建立研究区淹没水深-损失率函数,构建基于损失函数的城市洪灾弹性模型方法并计算了潍坊城区在遭遇5、50、100及200 a重现期降雨时的内涝弹性指数分布。同时,分析研究区在2012、2017和2022年3种不同土地利用情况下,潍坊市城区洪涝灾害弹性的时空变化趋势,揭示潍坊城区城市演化与区域洪涝灾害弹性响应关系。结果表明:潍坊市城区洪涝灾害弹性随重现期增加总体呈下降的趋势,且下降剧烈区域主要集中在人造地表面积占比较大的中心城区、街道和东部开发区,以及河流周边平坦低洼区域。从空间分布上看,这种下降趋势呈现出以主城区为中心向外扩张的趋势。此外,随着城市化程度的增加,研究区各分区的平均弹性指数均有不同程度的降低,其中C7山丘区一直处于弹性较高水平,C4高新开发区在多种模拟情景下均处于较低水平,并且在遭遇相同重现期降雨后,城市化程度越高,各分区的平均弹性指数降幅越大。研究结果为潍坊市应对未来增长的洪涝风险,实施城市洪灾弹性提升策略提供了科学支撑。

To enhance urban flood protection and resilience to floods,and to advance the new strategy of human-centered urbanization,Weifang′s urban area was selected as the study area.The CAflood model,based on cellular automata,was employed to derive inundation depth data.Using data mining and similarity analysis,urban loss rate was referenced and applied to establish an inundation depth-loss rate function for the study area.Based on this function,an urban flood resilience model was devel-oped,which was then used to calculate the flood resilience index distribution in Weifang′s urban area under rainfalls with 5,50,100 and 200-year return periods.Additionally,the temporal and spatial trends of flood resilience in Weifang′s urban area were analyzed under three different land use scenarios for 2012,2017 and 2022,revealing the relationship between urban evolution and regional flood resil-ience.The results indicated that the flood resilience of the Weifang′s urban area generally decreased with an increase in return periods.The most significant decreases were primarily observed in the cen-tral urban area,streets,and the eastern development zone,which have a higher proportion of man-made surfaces,as well as in the flat and low-lying areas around rivers.Spatially,the declining trend expanded outward from the central urban area.Moreover,as urbanization intensifies,the average re-silience index in each sub-district of the study area decreased to varying extents.Among these,the C7 hilly area consistently showed a higher level of resilience,while the C4 high-tech development zone exhibited lower resilience under various simulation scenarios.The higher the degree of urbanization,the greater the decrease in the average resilience index of sub-districts after the same return period rain-falls.The research results provide scientific support for Weifang to address the growing flood risk and to implement strategies to enhance urban flood resilience in the future.