Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/89391
標題: Experimental study of Flow Fields and Local Scour near Rigid Emergent Vegetation Patch
剛性非浸沒植生群周圍流場及底床沖淤之試驗研究
作者: 柯柏睿
Bo-Ruei Ke
關鍵字: 河岸
植生
流場
沖刷
River bank
Vegetation
Flow field
Scour
引用: 1. 朱家民,2003,「布袋蓮對渠槽曼寧係數之影響」,屏東科技大 學土木工程系碩士論文。 2. 楊克君,劉興年,槽叔尤,張之湘,2005,「植被作用下的复式 河槽漫灘水流紊動特性」,水利學報,第 36 卷第 10 期。 3. 王琪芳,2001,「基隆河河口紅樹林水流阻力之研究」,台灣大 學農業工程學研究所碩士論文。 4. Chen C. L. (1976). 'Flow Resistance in Broad Shallow Grassed Channels,' Journal of the Hydraulics Division, Volume 102, No. 3, pp. 307-322. 5. Chen F. Y. (1996). 'Turbulent shear flow in shallow open channel with Training Structures,' 東京技術學院. 6. Follett E. M. and Nepf H. M. (2012). 'Sediment patterns near a model patch of reedy emergent vegetation,' Department of Civil and Environmental Engineering, Massachusetts Institute of Technology Geomorphology, Volume 179, pp. 141-151. 7. Freeman G. E., Rahmeyer W. J. and Copeland R. R. (2000). 'Determination of Resistance Due to Shrubs and Woody Vegetation,' US Army Corps of Engineers. Engineer Research and Development Center. ERDC/CHL TR-00-25 8. Järvelä J. (2002). 'Flow resistance of flexible and stiff vegetation: a flume study with natural plants,' Journal of Hydrology, Volume 269, Issues 1-2, 1, pp. 44-54. 9. Melville B. W. and Chiew Y. M. (1999). 'Time scale for local scour at bridge piers,' Journal of the Hydraulics Engineering, Volume 125, pp. 59-65. 10. Nepf, H. M. (1999). 'Drag, turbulence, and diffusion in flow through emergent vegetation,' Water resources research, Volume 35, No. 2, pp.479-489. 11. Petryk S. and Bosmajian G. (July 1975). 'Analysis of Flow through Vegetation,' Journal of the Hydraulics Division, Volume 101, No. 7,pp. 871-884. 12. Ree W.O. (1949). 'Hydraulic characteristics of vegetation for vegetated waterways,' Agric. Eng., Volume 30 , pp. 184–189. 13. Raudkivi A. J. and Ettema R. (1983). 'Clear-water scour at cylindrical piers,' Journal of Hydraulic Engineering., ASCE, Volume 109, No.3, pp. 338-350. 14. Rominger J. T., Lightbody A. F. and Nep H. M. (2010). 'Effects of Added Vegetation on Sand Bar Stability and Stream Hydrodynamics,' Journal of Hydraulic Engineering, Volume 136, No. 12, pp. 994-1002. 15. Darby S. E. (1999). 'Effect of Riparian Vegetation on Flow Resistance and Flood Potential,' Journal of Hydraulic Engineering, Volume 125, Issue 5, pp. 443-454. 參考網頁 1. Nortek AS 儀器公司,http://www.nortekusa.com/ 2. 特 有 生 物 研 究 保 育 中 心 - 台 灣 野 生 植 物 資 料 庫 http://plant.tesri.gov.tw/plant100/index.aspx 3. 國 家 教 育 研 究 院 - 雙 語 詞 彙 、 學 術 名 詞 暨 辭 書 資 訊 網 , http://terms.naer.edu.tw/detail/568458/
摘要: 天然河道中,通常兩岸植生生長茂密,當水流經過時,會因為植生群阻擋而改變流場,進而使底床型態產生變化,底床之沖刷與淤積改變會影響河岸構造物的穩定性,本研究以試驗模型方式採用剛性之鋼棒,利用渠槽試驗模擬水流通過植生時流場之變化與受水流衝擊底床的改變,試驗過程分為平床與地形改變後的情況加以探討。 試驗過程將植生配置於渠槽中段靠單側邊壁,試驗流速為趨近泥砂起動之流速,觀察鋼棒周圍流場與泥砂沖淤的現象。流場量測使用Nortek Vectrino Profiler 以聲波原理對模型植生區密度為 0.05 周圍進行量測,底床之沖淤型態以雷射測距儀量測,試驗結果之分析探討分為平床流場以及水流沖刷後底床發展至穩定狀態時相應之流場,以及密度為0.03、0.05、0.09 及 0.12 之植生群對底床沖淤影響的差異,另有不透水組做為參考。 結果顯示水流受模型植生群影響,區內水流流速降低,平床與平衡後區域中心平均流速約為入口流速 0.4 倍,平床時底床上方紊流動能較大之區域與沖淤平衡後沖刷較深之位置相符。沖刷平衡後穿越植生區水流較多,因此區域後方渦流結構比平床時大。沖刷影響範圍與深度和植生密度成正比,密度愈高則沖刷範圍愈廣、深度愈深,密度0.12 沖刷深度為密度 0.03 的 1.56 倍,當密度大於 0.09 時,受堆積丘影響於下游產生第二沖刷區域。
In the natural rivers, woody vegetation commonly grows along the riverbank. When flows run through the woody vegetation zones, the stream processes are markedly affected. This study experimentally discusses the characteristics of flow fields and the changes of river bedform around woody vegetation zones. The experiments were produced in a flume with 20m long, 1m wide, and a fixed slope of 0.001. The woody vegetation was set in 10 square centimeters at one side of the flume. Modelled vegetation was simulated by the steel columns in the emergent flow conditions. Uniform sand with a median size of 0.88 mm was used as the bed sediment. The experimental flow was steady and flow velocity was adopted to close to the initiation of sediment motion. For the vegetation density equal to 0.05, the time-averaged three-dimensional flow fields and turbulent characteristics were measured by an Acoustic Doppler Velocimeter in the flat bed and equilibrium scour conditions. The bed morphology of equilibrium scour condition was measured by a Laser Distance Meter in the cases of vegetation density equal to 0.03, 0.05, 0.09, and 0.12. The interactions between water flows and river bed with vegetation ware investigated by observing the scour and deposition processes around the vegetation zone. When the flows passed through the vegetation zones, as a result, the approaching flow was retarded by the vegetation zone along the vegetation-bank side and accelerated in the main channel. The flow velocities also reduced downstream of the vegetation zones and the water depths dropped significantly in the streamwise direction. Near the vegetation zone, the size of the scour hole increased as the vegetation density increased. It was observed that the scouring depth in the case of vegetation density equal to 0.12 is 1.56 times of that in the case of vegetation density equal to 0.03.
URI: http://hdl.handle.net/11455/89391
其他識別: U0005-1606201512001300
文章公開時間: 10000-01-01
Appears in Collections:水土保持學系

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