中断面法及平均断面法应用於流量测定之比较.PDFVIP

中斷面法及平均斷面法應用於流量測定之比較 Comparison Study on Mid-Section and Mean-Section Methods for Measuring Flow in Canals and Rivers 財團法人農業工程研究中心 國立臺東大學公共與文化事務學系 副研究員 助理研究員 助理研究員 副教授 陳豐文 林修德 江慶星 蔡西銘 Feng-Wen Chen Hsiu-Te Lin Cing-Sing Jiang Shi-Ming Tsai 摘 要 流量測定過程包含通水面積參數測定及流速觀測，中斷面法及平均斷面法為流量測 定常用的斷面切割方法，其影響流速觀測點及水深的估測位置的選定，由於平均斷面法 與中斷面法之基本假設不同，以平均斷面法採用多個小梯形斷面的假設方式較適合描述 河川不規則的渠底條件，而平底渠道則無差異性。本研究為評估兩種方法測定流量之差 異，各選定 5處定型渠道及天然河道進行觀測試驗，結果顯示兩種方法獲得之流量差異 性小；最適宜的測定方式為河道兩側斷面採用中斷面法，而其他斷面則採用平均斷面法 的方式，可確保流量測定準確性及縮短測定時間。 關鍵詞：流量測定，中斷面法，平均斷面法，量測誤差 Abstract Process of flow measurement includes parameters of cross-section area and velocity observation. The mid-section and mean-section methods are the most commonly applied for dividing cross-section of river. Because these two methods are based on different hypotheses, and the method selection will affect the location for measuring flow velocity and water depth. Whereas irregular bottom of rivers are suitable described by the mean-section method, which of the method is divided as multiple small trapezoidal. Contrary, which one is selected is no matter in shaped channel (ex: irrigation canal). Five shaped channels and five sites of natural rivers are adopted to evaluate the variation between these two methods by experiments. The results show that only a slight difference between them. A combined method is the mid-section method used to measure flow in two subsections near sides of rivers, and the mean-section method is used for the other subsections at the same time. The combined method is recommended by the authors which it is suitable