台灣地理環境及條件特殊加上部分土地利用不適當，每逢颱風豪雨時極易發生土砂災害，其中最廣為人知的就是土石流。故於山區河道上設置了許多攔砂壩減少土砂運移，期保全下游居民之生命財產安全。天然河道中常因河道地形的束縮造成河道流況改變產生天然或人工之隘口均能改變流速，造成於隘口附近土砂的侵淤。由於特定流量下不同束縮比會發生瓶頸效應使得隘口上游處產生水躍現象，流速降低迫使土砂於隘口上游處堆積，產生防砂壩類似之效果，具減少土砂災害以及管理之應用潛力。
本研究以室內流槽進行水砂流的隘口實驗，透過高速攝影技術與粒子影像測速法(DPIV)探討隘口前的流速變化與土砂體的演化過程。搭配non-oscillating central (NOC)數值方法於地形座標系統上的數值模式來探討泥沙於隘口前的堆積演化。針對實驗量測之結果與不同侵蝕堆積率對於隘口前之堆積量準確率及命中率，且透過數值方法探討不同傾角、濃度、束縮率等條件對於堆積結果之影響。

Because of the specific climatic and geological conditions, Taiwan are suffering from the sediment-related disasters, of which the most famous one is the debris flow. Hence, there are many check dam constructed for reducing the sediment transportation as well as mitigating the impacts of the debris flows. On the river bed in nature, one can find narrowing passes, where the flow velocity changes due to the variation of the topographic geometry, and deposition or erosion might take place. With respect to specific narrowing ratio, the hydraulic jump may take place where the sediment deposits near the narrowing, implying a potential of mitigating disaster as well as sediment-management.
In the present study, experiments with respect to different narrowing ratios were performed in laboratory. The technique of image processing and particle image velocimetry (PIV) method were employed for investigating the flow dynamics and evolution of the deposition heap. A numerical model with non-oscillating central (NOC) method, based on terrain-fitted coordinate system, is applied to simulate the flow behavior and the development of deposition heap in one-dimensional case, so that we may evaluate the performance of variant erosion rates available in literature. Through numerical examples, the impacts of channel inclination, narrowing ratio and sedimentation concentration on the deposition heap were investigated.

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