利用連續落水頭入滲推估不同深度之土壤水力傳導係數之研究

Study of Using Multi-Step Falling-Head Infiltration to Estimate Hydraulic Conductivity at Various Depths

陳建泰(Chien-Tai Chen) ； 徐國錦(Kuo-Chin Hsu)

《農業工程學報》 58卷2期 (2012/06) Pp. 1-12

https://doi.org/10.29974/JTAE.201206.0001

摘要

傳統入滲試驗方法主要量測獲得單一深度下之均質土壤飽和水力傳導係數（Ks），本研究提出之連續落水頭入滲試驗（MSFIT），只需要在欲觀測深度下埋設含水量計即可估測不同深度下之水力傳導係數。模式以一維飽和垂直水流之落水頭入滲理論為基礎，延伸推導獲得連續落水頭入滲解析解，落水頭試驗次數與地表積蓄水位變化量將決定連續落水頭入滲模式之解析度。連續落水頭入滲模式亦應用於三組獨立之砂箱試驗，結果顯示連續落水頭入滲模式估測之水力傳導係數值與12個採樣分析所得之值相近，且模式所得之分層水力傳導係數結果亦與砂箱設計呈現出相同之遞減趨勢。本研究提出之連續落水頭入滲模式不僅操作簡單，亦可有效推估獲得不同深度之一維飽和垂直水流之力傳導係數值。

關鍵字

連續落水頭入滲試驗 ； 水力傳導係數

並列摘要

Most infiltration methods measure the saturated hydraulic conductivity (Ks) of the unsaturated zone at only one depth at or near the surface. The proposed model is extended the falling-head infiltration theory to a multi-step falling-head infiltration test (MSFIT) for estimating Ks at various depths in a one-dimensional saturated vertical flow domain. Water content sensors at various depths are required to add to the MSFIT. The resolution of the MSFIT is determined by the number of steps and the change of the ponded water head. The MSFIT is performed in three independent laboratory two-layer sand columns. The estimated hydraulic conductivity shows a consistent decrease in three independent laboratory sand column tests and is in agreement with the value obtained from twelve core samples using the constant-head method. The proposed MSFIT is simple, flexible, and versatile for obtaining hydraulic conductivity at various depths for one-dimensional saturated vertical flow domains.

並列關鍵字

Multi-step falling-head infiltration test ； Hydraulic conductivity