基于元胞自动机的低影响开发对城市内涝削减效果模拟

低影响开发措施是解决城市内涝问题的重要途径。为评估其对城市内涝的防控效果,论文以福建省长汀县县城为研究案例,提出适宜在研究区开展的透水铺装、下凹式绿地、雨水罐等低影响开发措施方案,利用基于元胞自动机模型的城市内涝模型进行模拟,并通过验证发现元胞自动机模型可有效模拟城市内涝过程。对比低影响开发改造前后的内涝情况,结果显示：1）低影响开发措施能使内涝积水总量削减超过50%,暴雨重现期越长对内涝现象的削弱效果越低;2）通过分析改造前后内涝积水区的空间格局及变化特征,可见大部分内涝积水区在改造后积水削减幅度较大,卧龙山北部及汀江干流左岸的积水区内涝情况改善幅度较小;3）低影响开发改造削减效果最好的为积水深度低于0.2 m的区域,其次为积水深度高于0.5 m的区域,对积水深度处于0.2~0.5 m的区域削减效果并不明显。研究表明低影响开发措施可有效控制城市的内涝灾害。

Cellular Automaton Simulation of the Effect of Low Impact Development on Urban Water-logging Reduction

Low Impact Development (LID) is an important measure to solve urban water-logging problem. To assess prevention and control effect of LID on urban water-logging, the urban area of Changting County in Fujian Province is taken as a case for study. Proper measures of LID for this area, including porous pavement, low elevation greenbelt and rainwater tanks, are proposed. The runoff generation module of SCS model and urban water-logging model based on Cellular Automaton (CA) model are used for simulation and verification. Results show that the urban water-logging model based on CA can simulate the process of urban water-logging effectively under the complex underlying surface scenarios of urban area. By comparing the water-logging simulation results before and after implementation of LID measures, the following conclusions can be drawn: 1) LID measures can reduce water-logging amount by over 50% under condition of different return period, and the reduction effect decline when the return period of storm is longer. 2) The spatial distribution and variation feature of water-logging area before and after LID measures are analyzed: After LID measures, water-logging amount reduces significantly in most water-logging areas, but the reduction is less in water-logging areas of northern Mountain Wolong and left bank of Tingjiang main stream, which means infrastructure construction such as drainage pipe networks should be strengthened in these areas. 3) The areas where LID has the best effect are areas where the water-logging depth is lower than 0.2 m, followed by areas where the water-logging depth is higher than 0.5 m. For those area where water-logging depth is between 0.2 m and 0.5 m, the reduction is not obvious. As the study shows, LID measures can control the water-logging disaster in a certain extent. Therefore, LID measures can be utilized as an effective complement to urban flood control and drainage engineering measures.