雨水口泄流计算对城市洪涝模拟结果影响研究

雨水口可将地表径流输送至排水管网，是城市洪涝治理中的关键因素。为充分掌握雨水口泄流机理，本文总结了泄流试验研究的主要成果，比较了不同泄流计算方法的优缺点及适用范围；通过编译生成SWMM动态链接库文件（DLL），构建了改进泄流计算的城市雨洪模型；以西安市沣西新城为研究对象，定量分析了不同泄流计算方法对汇水区内雨水口泄流量及洼地积水深度的影响。结果表明：典型汇水区内采用不同泄流计算方法模拟得到的泄流量占降雨总量的38% ~ 48%；泄流公式中流量系数18%的差异会在洼地积水深度结果中放大至55%；研究区各汇水区内因雨水口泄流能力不足而导致的最大洼地积水深度在0.1 ~ 0.6 m之间。研究成果有助于深化对雨水口泄流过程的认识，为城市防洪减灾提供技术支持。

Effects of calculation methods of stormwater outlet discharges on simulations of urban flooding

Stormwater outlets transfer surface runoff to the sewer network, playing a key role in urban flood control. To understand the stormwater discharging mechanism of the outlets, this paper summarizes the outlet discharging capacity in previous experimental studies and compares the pros and cons of different calculation methods and their application scopes. Then, we modify the source code of SWMM to create a dynamic link library (DLL), develop an urban flood model, and improve the calculations of stormwater outlet discharge. Through application in a case study of the Fengxi new town in Xi’an, different calculation methods are evaluated quantitatively in terms of the accuracy in the outlet discharge volume and the depth of depression storage over a catchment. Results show that for a typical catchment under a typical rainfall event, the total outlet discharge volume is 38% - 48% of the rainfall volume, as predicted by different methods. An 18% difference in discharge coefficient among the different formulas is amplified up to a 55% difference in the simulated depth of depression storage, and the maximum depth over the study area is in a range of 0.1-0.6 m due to insufficient capacity of the outlets.