集水區幾何與建物結構效應對都市漫地流的影響

Abstract

近年來，由於頻繁的強降雨事件以及都市化的快速進程，都市淹水災害已成為一個重要的問題。對於都市淹水而言，雨水的排放在淹水分析中至關重要，包括地表水流的集中和下水道系統中的運輸。然而，在過去的研究中，特別是在建築物結構的影響下，地表水流的集中並沒有得到很好的檢驗。過去因為都市地表徑流計算困難，在計算時需要消耗很長的時間。近年來，因為電腦設備的進步，二維水力模型已成為都市漫地流規劃和管理的重要工具。在本研究中，我們比較了兩種基於網格單元的水力數值模型。因此，我們可以透過模型對都市地區的地表漫地流流態有更好的瞭解。第一個模型是GSSHA，這是一個基於物理的分佈式模型，它以擴散波方程作為控制方程來進行數值模擬。第二種是HEC-RAS，它能使用擴散波方程和動力波動量方程來預測洪水過程的進展。利用這兩個水力模型，本研究主要探討流域形狀和建築物在洪水期間對水流流動的影響，以及它們是否為影響都市地區排水系統的重要因素。

Recently, urban flooding has become an important issue due to frequent heavy rainfall events and rapid urbanization. For urban flooding, the drainage of stormwater is essential in inundation analysis, including the concentration of overland flow and transportation in the sewer system. However, in the past, the concentration of overland flow has not been well examined, especially under the influence of building structures. In the past, the overland flow in the urban areas is hard to calculate and causing lots of computation time. Currently, two-dimensional hydraulic models become an important tool for flood planning and management. In this study, we compare two hydraulic numerical models based on grid cells. So, we can flow patterns of overland flow in the urban areas for better understanding. The first model is GSSHA, a physically-based, distributed model, which uses the diffusive wave equation as a governing equation to execute the numerical simulation. The second one is HEC-RAS, which uses either the diffusive wave or the full dynamic wave momentum equation to predict the progression of a flood hydrograph. With these two hydraulic models, this study focuses on how the geometry of the catchment shape and the constructions affect the water flow during the flood and whether they can be an important factor to influence the drainage system in the urbanized areas.