肖洋 王磊 张涛涛 冯雯

摘要：溶解态污染物是城市降雨径流污染的一个重要组成部分，揭示其在降雨径流阶段的传输过程对于城市污水治理具有重要意义。采用人工模拟降雨实验研究了不透水表面不同坡度（0.5°、1°、2°、3°、4°、5°）情况下降雨径流及溶解态污染物传输过程。结果表明：坡度越大，坡面产汇流时间越短，径流量越快达到稳定;污染物浓度随降雨径流深度增加呈逐渐减小趋势，坡度越大，初始浓度越高，衰减越快;污染物传输速率呈先增大后减小的变化规律，坡度越大，污染物传输速率峰值越大，峰值出现在径流深度为0.3～0.5 mm之间;溶解态污染物传输过程符合指数冲刷模型，随着坡度的增大，冲刷系数k先线性增加，坡度大于3°基本保持稳定。相对于颗粒态污染物，溶解态污染物冲刷系数大，易被冲刷，冲刷集中发生在径流初期。

关键词：不透水表面;降雨径流;污染物传输;溶解态污染物

中图分类号：TV131文献标志码：A开放科学（资源服务）标识码（OSID）：肖洋

Influence of slope on the dissolved pollutant transport process over impervious surface

XIAO Yang1，2，WANG Lei.2，ZHANG Taotao.2，FENG Wen.2

（1.State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering，Hohai University，Nanjing 210098，China;2.College of Water Conservancy and Hydropower Engineering，Hohai University，Nanjing 210098，China）

Abstract：Dissolved pollutants are an important part of urban rainfall runoff pollution.To reveal their transport process during the rainfall runoff stage is of great significance to urban wastewater treatment.In this study，we conducted a series of experiments to study the processes of rainfall-runoff and dissolved pollutant transport over impervious surface at different slopes （0.5°，1°，2°，3°，4°，5°）.The results showed that the higher the surface slope，the shorter the time of runoff yield and concentration，and the faster it took for the runoff volume to reach stability.The pollutant concentration would decrease as the rainfall runoff depth increased;the higher the slope，the higher the initial concentration，and the faster the attenuation.The pollutant transport rate would increase first and then decrease with time;the higher the slope，the larger the peak of pollutant transport rate.The peak of pollutant transport rate appeared when the cumulative runoff depth was 0.3 to 0.5 mm.The pollutant transport process conformed to the exponential wash-off model.The wash-off coefficient k would increase linearly first and then remain basically stable when the slope was above 3°.Compared with particulate pollutants，the dissolved pollutants had a larger was-off coefficient and were more likely to be washed off，especially in the initial runoff stage.

Key words：impervious surface;rainfall-runoff;pollutant transmission;dissolved pollutant

隨着城市化的快速发展，城市不透水面积急剧增加，一方面使得降雨产流时间缩短、洪峰流量增大、洪峰提前[1]，另一方面，雨水径流携带大量地表沉积物、营养污染物、重金属污染物等，汇入受纳水体，造成降雨径流污染，从而加重了城市水体的非点源污染问题[2-3]。因此，揭示城市降雨产汇流及污染物输移过程对于城市防洪和污染治理具有重要的科学意义。

鉴于降雨径流污染对城市水环境造成的严重危害……