A case study of river sediment transportation influenced by lowering the overflow and slit openings of a check dam
防砂壩 ； 輸砂 ； 切口壩 ； check dam ； sediment transport ； slit dam
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In 2009 the Pan-she-keng Creek in Yilan County during Typhoon Pama experienced a large sediment movement in the creek. The sediment was from a new landslide at the upstream watershed. The check dam actually provided storage function for the sediments. However, the riverbed was uplifted and expanded. The road along the creek was destroyed by the overflow debris and the debris also endangered the nearby residents. To properly adjusting the sediment transport condition of the creek, we proposed a treatment by reducing the level of the overflow opening of the check dam using a parabola profile and also lowered the slit opening to guide the centerline of the creek flow. This study uses field measurements and observation to discuss the change in riverbed slope, bedload size, and creek morphology before and after the treatment. We discuss the influence of the treatment by lowering the overflow and slit opening of the check dam on the counter-erosion structures downstream, and tried to understand the morphology of the creek bed after a couple of typhoons and intensive rainfalls to evaluate the overall effectiveness of the treatment. For current situation of the creek, the sediment transport condition has been improved. Key Words: check dam;sediment transport;slit dam.
生物農學 > 生物環境與多樣性