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近年来,中国城市暴雨内涝频繁发生,已经发展成为一类严重的“城市病”。城市不透水面密度及其空间格局是形成暴雨内涝的一个重要影响因素。本文提出一种耦合蚁群算法和SCS-CN水文模型优化不透水面空间格局的方法,从而实现通过增加地面雨水渗透量达到减缓城市内涝发生的目的。首先应用Williams公式计算基于坡度修正的CN值,在此基础上计算地表径流量;然后设定径流系数最小化目标,耦合水文模型和蚁群算法对径流小区尺度的不透水面空间格局进行优化配置;最后应用景观格局指数对不透水面空间格局进行分析。研究结果表明:面对1年、5年、10年、20年、50年以及100年一遇重现期的1 h持续降雨事件,研究区优化后的不透水面空间格局可以分别减少径流系数21.19%、19.58%、19.38%、18.93%、18.41%和17.25%,在一定程度上缓解城市暴雨内涝的发生。在此基础上,提出面向暴雨内涝防治的城市更新优化措施建议:(1)通过增加草地、花园、树木等植被绿化减少高不透水面类型的面积,并划分成更多中高不透水面类型的斑块;(2)集聚低、中低等不透水面类型,从而加大连通性,形成更多的中高不透水面类型;(3)增加每个径流小区内斑块数量,增大斑块密度,减少其蔓延度和聚集度。
In recent years, frequent floods occur in urban areas in China, and have become a serious “urban disease”. Urban impervious surface density and its spatial pattern is an important factor for the formation of storm waterlogging. In this paper, a method of coupling ant colony algorithm and SCS-CN hydrological model to optimize the impervious surface spatial pattern is proposed in order to achieve the goal of reducing the occurrence of urban waterlogging by increasing the infiltration of groundwater. Firstly, the Williams formula is used to calculate the CN value based on the slope correction, and then the surface runoff is calculated. Then, the minimum runoff coefficient target, the coupled hydrological model and the ant colony algorithm are used to optimize the impervious surface spatial pattern of runoff plot size Finally, the landscape pattern index was used to analyze the spatial pattern of impervious surface. The results show that in the face of 1-year continuous rainfall events of 1 year, 5 years, 10 years, 20 years, 50 years and 100-year recurrence times, the optimized impervious surface spatial pattern in the study area can reduce the runoff coefficient 21.19%, 19.58%, 19.38%, 18.93%, 18.41% and 17.25%, respectively, to a certain extent, alleviate the occurrence of urban waterlogging. On this basis, the suggestions of urban renewal and optimization for the prevention and control of rainstorm waterlogging are put forward: (1) The area of high impervious surface type is reduced by increasing the afforestation of grassland, garden and trees, and the area is divided into more middle and high impervious surface types Plaques; (2) low, medium and low impermeable surface types, thereby increasing connectivity and forming more types of high and medium impervious surfaces; (3) increasing the number of plaques within each runoff plot and increasing plaque Density, reduce its spread and degree of aggregation.