边滩倒伏植生排列分布对流场及床型之影响The - 中华水土保持学会.PDF

邊灘倒伏植生排列分布對流場及床型之影響 The Influence of the Flow Field and the Bed Form by Bent Vegetation Arrangements on the Riverside 李津甫 黃晉揚 陳樹群* Jin-Fu Li Chin-Yang Huang Su-Chin Chen 摘要 本研究以室內渠槽進行動床試驗，利用彈性材料之人工植株模擬遭受水流衝 擊的倒伏植生，研究不同排列型態之邊灘植生區，對於河川水流作用及底床沖淤 之影響 。渠槽分為邊灘植生區和主槽無植生區，試驗區總長3 m 、寬0.6 m ，而 植生區的寬度為0.3 m ，倒伏植株與床面夾角約為22∘。邊灘植生排列分為間隔 橫向、間隔縱向、連續橫向及連續縱向等四種配置。試驗結果顯示 ，連續縱向之 倒伏植生流速遞減比最大，水流往主槽無植生區集中之情形最為顯著，主槽沖淤 變化情形最為強烈。而間隔橫向種植對床型變化影響較小，具有穩定河床之作用， 為較佳的河川管理方式。 關鍵詞：灘地植生、床型演變、沖積河川 Abstract In this study, we used different arrangements of artificial elastic bent vegetation to simulate the influence of flow field and bed form variation in mobile-bed laboratory flume. The flume is 3 m long and 0.6 m wide, which is equally distributed onto riverside with vegetation and main channel without vegetation. The bent angle is 22° between the base of the vegetation and the bed. We conduct four types of arrangement, including interval transverse, interval longitudinal, continuous transverse, and continuous longitudinal. The results show that the continuous longitudinal arrangement has the maximum of velocity decrease ratio and directs flow to the main channel, which seriously scour the bed. The interval transverse arrangement has a minimum effect on bed form variation, which can stabilize. As a result, the arrangement of interval transvers is the best approach on the river management. Keywords: riverside vegetation, bed form variation, fluvial river 一、 前言 近年來由於氣候變遷影響，極端降雨事件頻傳，環境保育與河川棲地復育理 念逐漸受到重視，水利工程的設計考量不再只有安全規劃，還需要思考如何以友 善環境的方式，融入環境生態工法與自然保育的觀念。就灘地植生的正面價值而 言，植生群具有穩定河床、改善水質、調節水溫、控制沖蝕，並使河川棲地保有 生物遷徙之能力；但就河川管理而言，若放任植生在河道恣意生長，則可能因河 道容量減少，使洪患風險提高。為了能在兼顧安全及自然環境的原則下進行規劃 設計，灘