河口是海洋與河川之交會處,河口具有海洋潮汐、波浪與河川水文狀況互動而成之環境現象與特質。感潮河段之水理情形,主要受到河口潮位變化與河川上游流量的影響,隨著河川流量、潮汐強弱有別,河口段的位置也常有變動。在此流況複雜之河段觀測流量時,傳統流量觀測的準確性並不高,既耗時效率也低,因此有必要利用有別於傳統之方法觀測感潮河段流量。本研究量測淡水河流域包含淡水河本流之關渡橋、大漢溪之新海橋、新店溪之華中橋及基隆河河口之全潮流量資料,應用聲波杜普勒流速儀配合GPS系統安裝於船舶上,以船舶橫渡河川斷面之方式實際量測感潮河段流量;並應用以機率觀念為基礎之流速分佈理論,推求各測線之平均流速,進而以中斷面法做流量之計算。再利用量測資料建立一高效率感潮河段流量量測方法,藉由平均流速與最大流速之關係以及水位與通水斷面積關係求得斷面平均流速及通水面積,將兩者乘積後即可取得感潮河段流量資料。於本研究建立之高效率流量觀測方法結果良好,並具有相當之可靠度,可於未來測得即時流量,大幅降低於感潮河段流量量測之時間。
The estuary sited in a transition between ocean and stream. The estuary is the place that there is interaction between freshwater inflow and tide. The hydrodynamic in estuarine river is affected by inflow and tide, so that the end of the estuarine river is often changed. Measure discharge is inaccurately at estuary is affected by tidal. The tidal stream is unsteady, we need efficient method to measurement discharge. The study used the ADP and GPS system install on board to Measured discharge for complete tidal in the Tanshui River、the Keelung River、the Tahan River and the Sindian River. And accurate calculation of discharge by Chiu`s Velocity Distribution and the Mid-Section Method. Then Use the data to establish a efficient method of discharge measurement in tidal streams by relationship between mean velocity and maximum velocity and relationship between water level and cross-section area. This efficient method can be used with any current meter to reduce the time and cost of discharge measurement in tidal streams.