有效不透水面分布对城市雨水径流的影响

Impact of directly connected impervious area distribution on urban stormwater runoff process

城市区域不透水面分布错综复杂,汇流路径多样,不透水面有效性及其产流机制成为城市水文学的热点问题。研究以北京市主城区为对象,构建了基于汇水路径的有效不透水面的识别方法,拟合出总不透水面与有效不透水面的经验公式,定量识别了不透水面有效性对北京市主城区雨水径流的影响。结果表明:考虑不透水面有效性能显著提升模型模拟精度,针对不同城市化阶段,在各种重现期降雨情景下设置不同有效不透水面比例并进行模拟,发现有效不透水面对低重现期降雨产流过程的影响远大于高重现期降雨产流过程,且城市化前期有效不透水面增加会导致较大洪峰增长率,而城市化后期影响减小。研究可为优化城市地面格局,减缓城市洪涝灾害损失提供科学参考。

Given the complicated spatial distribution of impervious ground and its multiple flow routing paths in urban areas,the effectiveness of the impervious area and its runoff generation mechanism has become one of the hot topics in urban hydrology.In this work,we examine the core urban area of Beijing,construct a method for identifying its directly connected impervious(DCI)areas based on flow routing paths,and fit empirical equations for calculating its total impervious area and the DCI area.Based on the equations,the influence of DCI areas on the city’s urban rainwater runoff is quantitatively analyzed.The results show the accuracy of simulations is improved significantly by considering DCI areas.In different stages of urbanization,if different proportions of DCI areas are used to simulate the scenarios under the rainfalls with various return periods,DCI areas have a greater effect on the runoff process of a shorter recurrence period than that of a longer one.The increase in the DCI area in the early urbanization period leads to large peak discharge growth rates,but its effect decreases in the late stage.This work is useful to urban landform pattern design and urban flooding management.