碩士 / 國立臺灣大學 / 農業工程學研究所 / 89 / Kuan-Du Nature Reservation located at the confluence of Keelung River and Tanshui River is a typical river mouth wetland where the kind of mangrove Kandelia is develop in the adequate protection from tidal action. The vegetation in the Reservation was composed by Kandelia, Phragmites, and Cyperus. But at present, due to man-made dike construction and environmental effects, Kandelia spreads progressively and has become the dominant species of this area forming the particular mangrove swamps. Kuan-Du Nature Reservation is also situated within the waterway of Keelung River. The large area of mangrove is bound to retard water flow and reduce the passing area of water flow so as to increase the river water stage in flood events. The purpose of this study is to investigate the influence of resistance caused by mangrove in Kuan-Du Nature Reservation on water stage of Keelung River mouth. In order to provide a means of making strategies of the mangrove manegement in Kuan-Du from a flood control perspective.
In this study, empirical equations of vegetative resistance are used. To obtain the vegetative parameters, on-site Kandelia samples were investigated and experimented. Also the growth distribution of Kandelia in Kuan-Du Nature Reservation investigated by Taipei City Government is used. Then a two-dimensional numerical model, TABS-2, was employed to simulate the flood flow in the river.
The simulation results show that there are different resistance distributions under floods of various return periods. Within the four studied cases, the resistance caused by Kandelia is more significant in floods of 20-year and 10-year return periods, and is less significant in the flood of 2-year return period. The Manning’s roughness coefficients in the habitat area of Kandelia has similar trend to the growth distribution of Kandelia. That is, in the area of higher Kandelia, Manning’s roughness coefficient is larger. As the river discharge increasing, such as floods of 20-year and 10-year return periods, the hydraulic condition is less sensitive to vegetative resistance but is more sensitive when the river discharge becomes smaller.
| Identifer | oai:union.ndltd.org:TW/089NTU00404008 |
| Date | January 2001 |
| Creators | Chi-Fang Wang, 王琪芳 |
| Contributors | Ming-Hsi Hsu, 許銘熙 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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