基于SWMM的武汉市典型城区降雨径流模拟分析

Abstract

近年来，越来越突出的城市内涝问题对城市排水系统规划设计提出了更高的要求。目前我国城市排水系统规划设计中仍然主要以推理公式法计算洪峰流量，同时市政排水系统的设计重现期也偏低，一旦发生较大的暴雨，便可能导致城市内涝现象的发生。本文引进在国内外得到广泛应用的计算机数学模型SWMM(Storm Water Management Model)进行武汉市典型城区的降雨径流计算。建模步骤包括利用GIS进行汇水区的划分和属性数据的提取，管网系统概化、以及参数设置。应用所构建的模型对不同降雨情景下研究区排水管网运行状况进行了模拟。结果显示，随着重现期的增加，沙湖出水口径流总量和洪峰流量增加明显，同时管网节点溢流和管道超载情况趋于严重。研究区的排水管网系统能够满足设计标准，顺利的排走1年重现期的暴雨，但是随着重现期的增加，管网性能降低明显。 With the continuing urbanization, waterlogging problems in Chinese cities become more and more prominent, thus putting big pressures on the urban drainage network. In the urban drainage system design in China, the design recurrence interval of rainfall is often set to be very low, thus urban waterlogging can easily happen once big heavy rainstorm happens. Also, traditional rational formula method is still widely used to calculate peak flow from rainfall. This article introduces a hydrological model package named SWMM to simulate the rainfall-runoff processes in a typical urban region, named the Chu rivulet, in Wuhan city. Major steps of applying models include the use of GIS to discretize the study area into a number of sub-drainage areas and the extract of the attribute information for each sub-drainage area, the drainage network generalization, and the parameters setting and calibration. In order to analyze the operation conditions of the drainage system, the established model is applied in the study area under the rainfall scenarios with different frequencies. The results show that with the increase of recurrence interval of rainfall, the total runoff and peak flow at the Chu rivulet outlet increase, and the surcharging of the drainage network becomes more and more serious. It is concluded that the designed drainage system can drain away rainwater with recurrence interval of 1 year, but with the increase of recurrence interval of rainfall, the performance of drainage system degrades significantly.