| Summary: | 碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 99 === In recent years, the population is concentrated in urban areas because of the rapid development of metropolitan cities in Taiwan. Especially in Taipei City, there was the highest level of urbanization and dense population. In order to meet the requirement of residents, a large number of buildings were constructed. The original situation of surface water flows were changed by the additional buildings. As a result, the overland flow is confined by the reduction of the flow width and resisted by the form drag caused by the buildings.
The main purpose in this study is to develop an inundation model in a general computing grid which responses the storage and resistance effects of buildings for flooding. Building coverage ratio is a significant parameter in the simulation model. The Manning roughness coefficient is adjusted with confined flow resistance and building form drag. The flooding water flows into buildings when the inundation depth excesses a certain height which reflects the actual phenomena in the flooding with the buildings.
The model was applied on the central Taipei City which Tamsui River and Keelung River surround. It were compared the inundation depth and extent with and without the buildings existed. The rainfall data of Typhoon Nari event in 2001 was used for simulation. The results showed that in case of without considering the buildings, the inundation was underestimated in the metropolitan areas. Therefore, with consideration of the building coverage, the presented inundation model which adjusts the water flow conditions in accordance with the size of building in urban areas will make the inundation coincident with the actual situation of flooding.
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