基于SWMM的不同降水量对城市降雨径流TSS的影响分析

Simulation of Urban Runoff Quality Based on Stormwater Management Model

受物理、化学、生物等多重因素的影响,城市降雨径流水质的模拟研究比较模糊。以TSS(总悬浮固体量)为例,利用SWMM的污染物模块及其土地利用模块、污染物累积模块和污染物冲刷模块进行城市雨水径流水质模拟;考虑了不同土地利用情况对污染物的累积及冲刷的影响,针对不同的降水量,利用EMC法(平均浓度法)以及指数方程法进行污染物的冲刷模拟,指数方程法的模拟精度大于EMC法的模拟精度,与监测值更接近。指数方程法的模拟结果表明:当降水量小于2.5mm时,其TSS冲刷量增长幅度较缓;而当降水量大于3.5mm时,其TSS冲刷量呈显著线性增加关系,从而表明,降水量较大的降水事件对于TSS的冲刷量影响更为显著。

Due to influences of physical, chemical and ecological factors, simulation of the urban runoff quality is a very complex issue in the study of wet-weather flows and their environmental impacts. Taking total suspended solid （TSS） as an example, this paper simulated the building-up and washing-off TSS using the modules of pollutant, land use, build-up and wash-off of stormwater management model （SWMM）. Different land uses were taken into consideration for analysis. The event mean concentration （EMC） and exponential function were used to simulate the wash-off effects. Calibration process indicated that the exponential method was easier to calibrate than EMC. Simulation results of the exponential function indicated that the TSS had a slow increase when the rainfall depth is less than 1.25cm; however, there was a significant linear increase when the rainfall depth is greater than 0. 35 cm, which showed that greater rainfall had more significant impact on TSS wash-off rate.