高速公路雨水径流污染浓度的系统动力学模拟

针对降雨事件中高速公路雨水径流污染浓度变化的随机性复杂特征,建立了雨水径流污染物浓度演化的系统动力学模型,研究交通流特征、高速公路特征、降雨事件特征对雨水径流污染浓度的影响。利用模拟软件Anylogic,基于5条高速公路的21个降雨事件抽样数据,对模型进行了拟合分析。通过对模型中降雨时间、径流深度、降雨量等参数进行敏感性分析,阐明了不同降雨事件情景下雨水径流污染浓度的时变规律。结果表明:提出的系统动力学模型可以很好地模拟降雨事件中雨水径流污染浓度的变化过程;在持续时间短而强度高的降雨事件中,高速公路雨水径流污染浓度较高,对沿线受纳水体的影响较大;雨水径流深度与污染浓度是正相关的,降雨量大的雨水径流中污染物的最大析出浓度反而会比降雨量小的降雨事件提前出现;在降雨事件的前期,如果选择合理的控制措施,可以显著降低雨水径流的平均污染浓度。

System dynamics simulation of pollution concentration of rainwater runoff on expressway

As for the pollution concentration of rainwater runoff on the expressway changed randomly and complicatedly, a system dynamics model for pollutant concentration evolution in rainwater runoff was built to study the influence of traffic flow characteristics, expressway characteristics, and rainfall event characteristics on the pollution concentration of rainfall runoff. The simulation software, Anylogic, was applied to conduct fitting analysis on sample data of 21 rainfall events on five expressways. Through the sensitivity analysis on the parameters of rainfall duration, runoff depth, rain capacity, etc. , the time-varying regularity of the pollution concentration of rainwater runoff in different rainfall events was clarified. The results shows that the system dynamics model proposed in this paper can simulate the changes of pollution concentration in the rainfall events accurately. In the certain rainfall event with high intensity and short duration, the pollution concentration of rainwater runoff on expressway is relatively high, which has great influence on the receiving water body along the expressway. There is a positive correlation between the rainfall runoff depth and pollution concentration, and the max release concentration of pollution emerges earlier in the high rainfall runoff than in the low rainfall runoff. Therefore, in the early stage of the rainfall event, the average pollution concentration of rainfall runoff can be significantly reduced if reasonable control methods are adopted.