陡坡卵礫石小型河川底床推移載之現場量測與經驗公式之比較－以筏子溪為案例

Field Measurements of Gravel Transportation and Comparison with Bedload Formulas in a Small River with a Steep Slope-Fa-Zih River Used as an Example

劉建榮(Chien-Jung Liu) ； 許少華(Shao-Hua Hsu) ； 蘇宏仁(Hung-Ren Su)

《中華水土保持學報》 42卷2期 (2011/06) Pp. 160-173

https://doi.org/10.29417/JCSWC.201106_42(2).0008

摘要

目前台灣河川推估推移載輸砂率多以經驗公式或者總輸砂量的固定比例作為推移載傳輸量，缺乏現地實驗數據驗證，可能錯估大水期間的推移載傳輸量。本研究利用自行研發的推移載採樣器於台中市筏子溪進行現地量測。根據試驗結果可知，表面流速高於3.8 m/s以上時，幾乎所有的河床質皆已啟動。何智武－A1與A2公式以及MPM公式較適用於筏子溪進行推移載輸砂率推估。Parker經驗公式所推估之輸砂量與實際值有所差異應為所給定之護甲層資訊需根據不同颱洪事件進行修正。由敏感度分析可知，何智武－A1與A2公式的估算對S與D50之變化較為敏感，此有助於釐清推估颱洪期間推移載傳輸量時所應強調的重點參數。

關鍵字

推移載 ； 現地量測 ； 輸砂公式

並列摘要

Currently, the bedload transport rate is usually estimated by empirical formulas or by assuming a ratio between the bedload and suspended load. Without proper confirmation by field data, the predicted value might be far from the real value. This study employed a newly invented instrument to measure the bedload transport rate in Fa-Zih River, Taichung, during Typhoon Sinlaku in 2008 and Typhoon Morakot in 2009. The data from the three field experiments showed, almost the entire bed material would move when the surface velocity reached 3.8 m/s. The He-Zhi-Wu-A1 & A2 and MPM empirical formulas were more suitable to evaluate the bedload transport rate than other empirical formulas. For the He-Zhi-Wu-A1 & A2 empirical formulas, the predicted bedload transport rate is very sensitive to the bed slope parameters and mean grain size D50. It was useful to understand what parameters should be emphasized to evaluate the predicted bedload transport rate on Fa-Zih River during typhoons.

並列關鍵字

bed load ； sediment transport