漂流木運移特性對河川型態改變之試驗研究

The Influence of Large Woody Debris Movement on the River Morphology in Flume Experiment

陳樹群 ； 趙益群 ； 陳佳璜

《中華水土保持學報》 41卷1期 (2010/03) Pp. 111-125

https://doi.org/10.29417/JCSWC.201003_41(1).0008

摘要

本研究利用渠槽試驗探討漂流木對河川型態改變之影響。試驗結果發現漂流木沉積於河道能有效阻擋或分散水流，甚至加速主深槽擺盪的頻率，使得整體河道流路變化豐富。漂流木因能降低水流流速，促使整體河床沖刷深度減緩，降低輸砂量，並能使泥砂能夠有效地沉積於漂流木下游處。在漂流木之沉積型態方面，漂流木平行於水流之比例為最高(42%)，依次為傾斜於水流(32%)及垂直於水流(26%)。而漂流木之運移速度則與長度成反比。另外，聚積且穩定的漂流木能夠有效地攔阻泥砂，並降低漂流木的移動速度。

關鍵字

漂流木 ； 沉積型態 ； 漂流木聚集

並列摘要

This research used the flume experiment to explore the influence of large woody debris (LWD) on river morphology. The results indicated that the LWD deposited on the channel could effectively block or separate the flow, and even accelerate the frequency of vibration of main channel so that the channel could become abundant. Because the LWD could lower the flow velocity, the scour depth of riverbed would decrease and the sediment transport would reduce as well as the sediment could be deposited effectively in the downstream of LWD. In regards to the deposition patterns, the percentage of LWD parallel to the flow (42%) was the highest, following the percentage of LWD oblique to the flow (32%) and the percentage of LWD perpendicular to the flow (26%). The transport velocity of LWD is inversely proportional with the LWD length. In addition, the accumulative and stable LWD could effectively deposit the sediment and lower the movement velocity of LWD.

並列關鍵字

Large woody debris LWD ； deposition pattern ； LWD jam