城市暴雨地表积水过程研究：以清华大学校园为例

我国正处于城市化的高速发展阶段，不透水地表面积增大，导致城市内涝风险增加。本研究考虑建筑物、道路、绿地和雨水口等城市地物特征，旨在对降雨-径流过程进行精细模拟，对地面排水系统的能力进行评估。采用二维水动力学模型，以北京市清华大学校园为研究区域。通过两场降雨过程中积水点的实测水深对水动力学模型进行率定和验证，结果表明该高分辨率模型能够比较准确地计算出地表积水深度。在采用压强式水位计记录降雨过程中积水点压强时，必须同时记录大气压强的变化，否则水深会有一定的误差。基于上述结果，以2012年7月21日暴雨为例，对清华大学校园进行大暴雨情景的地表积水过程模拟，结果表明雨水口总排水量随降雨过程变化较大，地表积水主要通过雨水口排走，降雨结束时雨水口排水总量约占降雨总量的70.0%，而土壤入渗量较少，仅占降雨总量的11.1%。

Surface flooding in urban areas under heavy downpours: Case study of Tsinghua University campus

Along with rapid urbanization, imperious ground surfaces are expanding dramatically in China, resulting in a higher risk of urban flooding. This study focuses on accurate high-resolution simulations of rainfall-runoff process over an urban area featured with buildings, roads, grass lands and street outlets, and examines the performance of its surface drainage system. A two-dimensional hydrodynamic model is used in a case study of the Tsinghua University campus in Beijing, and it is calibrated and validated against the pressure gauge measurements of water depth at two waterlogging sites under two heavy downpour events. The results show accurate predictions of the surface flooding water depth and the necessity of using atmospheric pressure data recorded during the downpours to reduce the errors in water depth calculations that are otherwise significant. A detailed examination on overland flow patterns under a downpour of July 21st, 2012 reveals significant variations in the total runoff drainage into all the street outlets with different rainfall processes. Most of the surface impoundment was drained into rainwater outlets and 70.0% of the total rainfall volume released through surface runoff into the drainage system, while only 11.1% was through surface infiltration.