城市典型下垫面产流过程模拟实验

城市化的快速发展直接改变了城市下垫面,造成城市水文循环条件的极大变化。研究地表产流在不同下垫面条件下的变化过程将对城市防洪减灾及雨洪有效利用提供重要启示。本文基于人工降雨和城市下垫面模拟技术,探讨城市典型下垫面类型（不透水面﹑绿地及透水砖）及不透水面分布格局在两种雨强（0.29mm/min和0.56mm/min ）条件下的降雨产流过程。结果显示：雨强及下垫面条件对产流效应及径流变化过程均有较显著影响。表现为：①雨强越大,产流时间越短,产流总量及稳定产流量越大;②低雨强条件下,绿地及透水砖间的截流能力差异较小,随着雨强的增大,两者间呈现出明显的差异,但均明显优于不透水面。三种下垫面的产流效率表现为：不透水面>透水砖>绿地;③同种雨强条件下,三种不透水分布位置间的产流效应差异显著,下部不透水的小区地表积水较快,而小区上部不透水时产流较慢,具有很好的截流效果。该结论不仅能为城市雨洪有效利用与灾害防控提供技术支持,还可为城市景观规划与设计提供参考。

Experimental study on typical city underlyings runoff process

With rapid urbanization in China,land surface features in built-up regions have changed,causing marked alterations in hydrological conditions. Knowledge of the relationship between surface runoff and urban landscapes is extremely crucial in preventing city flooding and enhancing rainwater harvesting. The study made full use of an artificial rainfall stimulator to examine the effect of land surface type and impervious building distribution on runoff generation under two rainfall intensities （29 mm·min^-1 and 0.56 mm·min^-1）. The results showed that both rainfall intensity and land surface condition have significant effects on the responses of runoff generation and dynamics. First,with increasing rainfall intensity,the runoff time was shorter and the amount of runoff and the steady runoff rate were greater. Second,different types of land surfaces play various roles in rainfall runoff processes. Compared with impervious land surface,the green space is more effective in intercepting rainfall and delaying runoff. A permeable brick can intercept more rainfall in low intensity,but the intercept effect is poorer in high intensity. Finally,under the same rain intensity,the effect on runoff of the three watertight distribution patterns was different. When the watertight part was in the upper of the cell the runoff time was long,however,the watertight part in the lower was short. Such findings provide technical support for urban rainwater utilization and control and a reference for urban landscape planning and design.