基于SWMMH雨水管理模型的降雨径流对排水沟影响分析

Impact analysis of rainfall runoff on drainage ditches based on SWMMH rainwater management model

当满足一定地表产流条件时,随着降雨强度及持续时间的增加,地表径流对实际工程的影响更加直观。以某生态修复提升改造项目为例,阐述了研究区降雨径流方向,构建了研究区地形3D模型,利用SWMMH雨水管理模型进行降雨径流数值模拟,分析了排水设施不同管段在不同降雨条件下地表径流的汇水深度和流速。结果表明:降水形成的地表径流随坡向汇入排水沟,在16 mm/h、115 mm/d、267.9 mm/d三种不同降雨强度和1 h、1 d两种降雨持续时间条件下,模拟排水沟内各管段汇水深度最大值均未超过其设计深度。三种降雨情形下径流途径土体介质到达饱和含水率的时间分别为2 h、2.5 h、1.5 h,若持续降雨时间较短,则汇水深度、流速增大趋势的拐点会随降雨结束呈现出滞后性,且汇水深度、流速的变化趋势不稳定。土体介质到达饱和含水率的时间与降雨强度呈负相关,沟道易积累堵塞物位置不会因降雨强度和持续时间而明显变化。

When certain surface runoff generation conditions are met,with the increase of rainfall intensity and duration,the impact of surface runoff on the actual project is more intuitive.Taking an ecological restoration and upgrading project as an example,the direction of rainfall runoff in the study area is described,the terrain 3D model of the study area is constructed,the SWMMH rainwater management model is used to conduct numerical simulation of rainfall runoff,and the catchment depth and velocity of surface runoff in different pipe sections of drainage facilities under different rainfall conditions are analyzed.The results show that the surface runoff formed by precipitation flows into the drainage ditch along the slope direction.Under the conditions of 16 mm/h,115 mm/d,267.9 mm/d rainfall intensity and 1h,1d rainfall duration,the maximum catchment depth of each pipe section in the simulated drainage ditch does not exceed its design depth.Under three rainfall conditions,the time for runoff to reach saturated water content through soil medium is 2h,2.5h and 1.5h respectively.If the duration of rainfall is short,the inflection point of the increasing trend of catchment depth and flow rate will show hysteresis with the end of rainfall,and the changing trend of catchment depth and flow rate is unstable.The time when the soil medium reaches the saturated water content is negatively related to the rainfall intensity,and the position where the channel is easy to accumulate blockage will not change significantly due to the rainfall intensity and duration.