新一代都會區地表與雨水下水道水流互動之淹水模擬

A New Approach to Model Dynamic Flow Interactions between Storm Sewer System and Overland Surface in Urban Areas

王嘉和(Chia-Ho Wang)

指導教授 ： 張倉榮

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.11280

摘要

本研究開發了一種新的二維淹水模式結合一維雨水下水道模式之特殊交互演算模式，其模式可以依據不同的土地覆蓋情況給予不同的一維雨水下水道與二維地表漫地流結合方法。當降雨落在道路、廣場、人行道時，降雨在進入雨水下水道系統前會以地表漫地流形式流入集流器，降雨所形成的地表漫地流過程在二維淹水模式中直接模擬，當地表漫地流經集流器進入雨水下水道系統，被視為進入一維下水道模式；而當降雨落在綠地，則直接以二維淹水模式模擬二維地表漫地流；若降雨下在建築物屋頂時，於模式中直接將雨水從屋頂排入雨水下水道之中，因此，於建築物區域二維網格只作為一維雨水下水道模式之水文區域畫分，此時建築物區域不進行二維淹水模式演算。
當雨水下水道系統流量超過其容量時，會於人孔產生溢流現象，從一維雨水下水道模式以一點源流量輸入二維淹水模式之中，當人孔溢流量進入二維淹水模式時，會因其二維地表高程、水位差而產生二維漫地流，當此水流流經一個未滿管之下水道系統時，會再次返回雨水下水道系統中，並進行下一時間之一維雨水下水道演算。
本研究利用此新模式進行與其他五種都會區淹水模式進行比較，並以4場淹水事件進行模擬與分析，根據模擬結果發現此新模式所模擬的4場淹水事件均較接近實際淹水調查記錄，因為此模式於都會區有較符合實際物理機制的表現。

關鍵字

分離演算 ； 交互演算 ； 屋頂排水 ； 漫地流 ； 雨水下水道

並列摘要

In this study, we developed a novel approach to simulate dynamic flow interactions between storm sewers and overland surface for different land covers in urban areas. The proposed approach couples the one-dimensional (1D) sewer flow model (SFM) and the two-dimensional (2D) overland flow model (OFM) with different techniques depending on the land cover type of the study areas. For roads, pavements, plazas, and so forth where rainfall becomes surface runoff before entering the sewer system, the rainfall-runoff process is simulated directly in the 2D OFM, and the runoff is drained to the sewer network via inlets, which are regarded as inputs to the 1D SFM. For green areas where rainfall falls into the permeable ground surface and the generated direct runoff traverses terrain, the deduction rate is applied to the rainfall for reflecting the soil infiltration in the 2D OFM. For flat building roofs with drainage facilities allowing rainfall to drain directly from the roof to sewer networks, the rainfall runoff process is simulated using the hydrological module in the 1D SFM where no rainfall is applied to these areas in the 2D OFM. The 1D SFM is used for hydraulic simulations in the sewer network. Where the flow in the drainage network exceeds its capacity, a surcharge occurs and water may spill onto the ground surface if the pressure head in a manhole exceeds the ground elevation. The overflow discharge from the sewer system is calculated by the 1D SFM and considered a point source in the 2D OFM. The overland flow will return into the sewer network when it reaches an inlet that connects to an un-surcharged manhole. In this case, the inlet is considered as a point sink in the 2D OFM and an inflow to a manhole in the 1D SFM. The proposed approach was compared to other five urban flood modelling techniques with four rainfall events that had previously recorded inundation areas. The merits and drawbacks of each modelling technique were compared and discussed. Based on the simulated results, the proposed approach was found to simulate floodings closer to the survey records than other approaches because the physical rainfall runoff phenomena in urban environment were better reflected.

並列關鍵字

Coupled 1D/2D flood model ； Dynamic flow interaction ； Overland flow ； Roof drainage ； Storm sewer flow

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