圖書典藏及影音數位平台

臺灣位於環西太平洋地震帶，地質脆弱，降雨集中於梅雨及颱風時期，河道屬間歇河性、坡陡流急。洪汛期間單場颱洪之河道短期沖淤激烈，加上河川行水區內設置各項水工構造物等人為干擾，加深防洪沖刷治理之複雜性。尤其，全球暖化氣候異常，降雨分布更趨於高強度集中降雨及長延時，921大地震後抬升中部主要流域河床，加促泥岩裸露，長期及短期一般沖刷更趨急遽，河道穩定及沖刷問題嚴峻。例如大甲溪客庄堤防於2001年桃芝颱洪、2004年敏督利颱洪後72水災及2008年辛樂克颱洪等之毀堤，重複修堤影響民眾對工程設計及防災信心。濁水溪2009年莫拉克颱洪沖刷台16線水里集集段路堤，人車落河危害人民生命財產安全；2012年610梅雨水災水底寮堤防及集集共同引水南岸聯絡渠道毀損，影響水資源調度。鑑於河道深槽渠化，導致颱洪彎道斜向流基腳沖刷日益嚴重，亟須釐清沖刷物理機制，掌握防災抗洪關鍵。本計畫主要目的，係就長期一般沖刷顯著河段，進行颱洪彎道堤基之動態沖刷觀測，據以瞭解台灣間歇河性之彎道沖刷過程，提供物模試驗分析之率定驗證與堤防基腳及其保護工設計之工程實務參考。

The short–term river bed scour caused by the rapid flow discharge variation for the intermittent rivers with steep slope and gravel bed in Taiwan, is quite different from that of the perennial rivers. For river bends in the Daann River and Dajia River, the embankment scour failures frequently occurred at attacking toes of the oblique flow. In the 2-yr project (2017~2018), the field experiments were conducted using the real-time wireless tracer scour monitoring IoT system during typhoon-induced floods in the Shuiwei Embankment and Fongchou Embankment stations, respectively. Further, the semi-empirical model for bend scour under unsteady flow was established and tested with the physical model data collected by the Water Resources Planning Institute (WRPI). The proposed model also gave reasonable fitting for the field bend scouring data. To sum up, this project has achieved all the expected results during the executed period.