由於生態工法盛行，造就地工合成材成為各項工程施造之熱門材料，儘管地工合成材之相關研究眾多，但多著重在滑動、傾倒、應力破壞等方面，然在水利工程之水理特性研究仍有所缺乏，緣此本研究以實驗渠道進行試驗，探討不同地工合成材之阻力特性。本研究結果適用於一般明渠之流況，可提供相關工程設計之參考。
以定量緩變速流理論分析四種地工合成材之阻力係數，於實驗條件下之各材料曼寧粗糙係數隨水深增加而有遞減之趨勢，並以統計迴歸之方式得各材料曼寧粗糙係數與水深之迴歸關係式，加以分析曼寧粗糙係數之變化。由曼寧粗糙係數經轉換式得之Darcy-Weisbach摩擦係數，有類似曼寧粗糙係數之變化，各材料之摩擦係數隨雷諾數增加而有遞減之趨勢。

Due to famous of ecological engineering which makes geosynthetics to become very popular material for engineerings. Although there are a lot of researches about studying geosynthetics, but most of them are focusing on slipping, prone, and stress fracture; however, we still lack of some focusing researches about hydraulic characteristics in Hydraulic Engineering, so this study is discussing the characteristics of resistance of different geosynthetics by testing with experience channel. The results of this study apply to the general open channel flow witch can provide information for design of engineering.

The resistance coefficients of four kinds of geosynthetics were analyzed by steady gradually varied flow theory, and Manning’s roughness coefficients of geosynthetics decreased with increasing water depth within experimental conditions. The relationship with Manning’s roughness coefficient and depth that obtained by statistical regression to analyze the variation of Manning’s roughness coefficient. The Darcy- Weisbach friction factor that transferred form Manning’s roughness coefficient witch have similar variation of Manning’s roughness coefficient, and friction factor of geosynthetics decreased with increasing Reynolds number.

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