台灣山區陡坡河道曼寧糙率係數估算研究

Estimating the Manning's Roughness Coefficients of Steep Channels in Taiwan

何智武(Chih-Wu Ho) ； 游功揚(Kung-Yang Yu)

《中華水土保持學報》 30卷3期 (1999/09) Pp. 215-221

https://doi.org/10.29417/JCSWC.199909_30(3).0005

摘要

曼寧公式由1889年開始使用至今，由於具有簡易及豐富的實際檢定驗證資料，因此被廣泛的用於渠道均勻水流之分析。公式中的曼寧糙率係數經由多年之研究，已可藉由查圖表及照片對照等簡易方式求得。但所得之値以緩坡渠道水流較爲適用，對於台灣山區陡坡河道而言，經實驗與現場數據分析發現，相同流況與底床粒徑下，陡坡河道之曼寧糙率係數遠較緩坡渠道爲大，因此本研究分析發現陡坡河道之曼寧糙率係數必須加入坡度因子以修正之。

關鍵字

陡坡河川 ； 曼寧糙率係數 ； 粗顆粒沉滓

並列摘要

The Manning formula was proposed in 1889, with an effort to correlate and systematize the existing data from natural and artificial channels, Because of the simple form and satisfactory results for practical applications, the Manning formula has become one of the most widely used of all open-channel, uniform-flow formulas. The standard references for estimating roughness coefficients by the figure, table and visual comparison approach can be employed in their own right in hydraulic calculations. Alternatively, and preferably, they can be used either to verify or as t he base values for estimates of roughness coefficients, obtained by more quantitative methods. However, those methods are for mild slope rivers. The roughness coefficients of steep upstream channels are larger than that of mild downstream channels in some river bed condition in Taiwan. Therefore, the estimation of Manning's roughness coefficients have been revised by adding slope factor in this research.

並列關鍵字

steep channel ； Manning's roughness coefficient ； gravel sediment