在進行河川、野溪整治及探討水理、輸砂問題時,河床質的組成是重要影響因素之一。一般而言,河道底床糙度,為河道設計的主要水理因素,常以慣用的曼寧粗糙係數值表示。其數值之合理與否,直接影響工程規劃設計之精密度與安全性。 本文由表面採樣與樣坑採樣試驗結果,利用統計分析軟體,針對影響河床質粒徑大小的自然環境因素進行一系列的多元迴歸分析,希望能建立一套預估台灣東部溪流卑南溪的曼寧粗糙係數之估算函數式,並探討樣坑與表面調查採樣方法的結果差異性。 研究結果顯示,曼寧粗糙係數與崩塌面積、溪流長度、河床坡度及平均粒徑等因數呈正比關係,其集水區面積與溪流流速則呈現反比關係。而不同的採樣方式對於曼寧粗糙係數並不存在明顯的差異性,但表面採樣所取得曼寧粗糙係數較樣坑採樣更具有解釋變數與變異程度之能力。
Bed material is one of the most important influence factors to study the flow resistance, particle initial movement and sediment transport. In general, rough degree of river-bed bottom expressed by multiple regression、Manning’s roughness coefficient is a major factor of flow resistance, and it influences the precision and safety of the structures directly. In this study, environmental factors of bed-material particle size were analyzed by the surface samples and hole samples used SPSS statistical analysis software to establish function of multiple regression、Manning’s roughness coefficient. This study indicated that landslide area, river length, slope of riverbed and mean diameter particle were positive correlation. Furthermore, watershed area and velocity of river were negative correlation. Our data demonstrated that different sampling methods did not show various effects on multiple regression、Manning’s roughness coefficient. However, the multiple regression、Manning’s roughness coefficient of surface sample could explain the correlation between independent variable and dependent variable.