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題 名 | 利用溫度日變化推算河床入滲流速=Using Diurnal Temperature Time Series to Determine the Streambed Percolation Velocity |
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作 者 | 陳文福; 張閔翔; 黃智昭; 王詠絢; 江崇榮; | 書刊名 | 農業工程學報 |
卷 期 | 58:4 2012.12[民101.12] |
頁 次 | 頁67-79 |
分類號 | 443.67 |
關鍵詞 | 溫度法; 河床; 入滲流速; 阻塞層; Temperature method; Streambed; Percolation velocity; Clogging layer; |
語 文 | 中文(Chinese) |
中文摘要 | 河床入滲是地下水主要的補注來源之一,以溫度法量測河床入滲為一常用的方 法,在河床面及河床下至少埋設兩處溫度記錄器,使用至少兩測點的溫度時間序列, 然後以解析或數值解求得入滲流速。常用的地下水傳輸及傳熱的數值模式如 VS2DH、SUTRA 或TOUGH2 等,但都並非專供求解河床入滲率之用,主要是用來 模擬地下水之二維至三維的熱能傳輸問題。本研究則使用一維熱傳公式,假設只有 垂直向的對流與傳導,不考慮水平方向,撰寫求解的數值程式,只要將實測的河床 面及河床下兩組溫度數據代入,便能自動求解。因為假設為一維之熱傳問題,所以 不需事先建構二維水流模式。而且本程式以每日的溫度變化為計算單位,所以如果 有多天數據,便可求出每天的河床入滲流速,對於河流的入滲型態能有更深入的認 識。 本研究並在彰化縣二水鎮濁水溪支流進行實測,發現河床入滲流速平均約2.63 × 10-5 m/s,推算垂直水力傳導係數平均約3.27 × 10-5 m/s,與前人研究的水力傳導係 數約10-3 m/s 相差甚大,且入滲流速也與河流水位高低沒有關係,推測乃因河床面的阻塞造成入滲流速與水力傳導係數的降低。本河段的地下水面可能深達河床下 20-30 m,加上河床面有阻塞層,可能造成所謂「不連通河」。 |
英文摘要 | Streambed percolation is one of the most important routes for groundwater recharge. Among many methods, using diurnal temperature time series in streambed to determine the percolation velocity is one the most using methods. At least two temperature logs should be installed, one in the streambed of 10-100cm in depth and one on the streambed surface. Percolation velocity then is calculated from those temperature time series by analytical or numerical procedures. Several numerical codes, e.g. VS2DH, SUTRA, TOUGH2, were developed for 2D or 3D heat transport simulation and also were using for streambed percolation velocity calculation, but, with great complexity. In this research, we simplify the calculation by developing new computer codes that solve the 1D heat transfer equation. Using the diurnal temperature data, we can calculate the percolation velocities of each day. With more percolation velocities data there will be have more understanding for the river/groundwater interaction. We also conducted a field test for studying the streambed percolation in a tributary of the Choshui stream, central Taiwan. Our data show that the average percolation velocity is about 2.63 × 10-5 m/s and with a vertical hydraulic conductivity of 3.27 × 10-5 m/s. The calculated hydraulic conductivity is too small than values of about 10-3 m/s from the previous studies. In our data there is no correlation between percolation velocity and river water level. We suggest that the streambed was clogging of the percolation surface and resulting reduction in percolation velocity and hydraulic conductivity. The studying stream section could be a “disconnected stream” because of the groundwater table is probably as deep as 20-30 m below the streambed and with a clogging layer deposited on it. |
本系統中英文摘要資訊取自各篇刊載內容。