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|標題:||A Study for Determining the Parameter θr of van Genuchten Model under High Pressure Condition
在高張力條件下決定 van Genuchten 模式的殘餘水分 含量（θr）參數之研究
|關鍵字:||soil water characteristic curve;soil residual water content;pressure plate extractor;土壤水分特性曲線;土壤殘餘水分含量;壓力鍋||Project:||水土保持學報, Volume 48, Issue 4, Page(s) 1895-1916.||摘要:||
In this study, the measured high-pressure water content of 30 kinds of soil samples was obtained by pressure plate extractor, and measured -1500kPa water content data as residual water content was suggested by van Genuchten (1980). In addition, θr was regarded as an unknown parameter, and determined by curve fitting. Eight kinds of different methods were applied to estimate residual water contents. The practicality and applicability of these methods were discussed separately, in order to determine the parameter θr of van Genuchten model under high pressure condition. The result showed that the best-fit θr, which was regarded as an unknown parameter, is able to come out the trend of measured data, and it is the most simple and rapid method. However, in the absence of measured high-pressure data, the curve fitting method combined with soil moisture factor (MF – 1) or the USDA – NRCS (2011) empirical formula, is used to estimate the residual water content so as to establish a soil water characteristic curve closer to the measured high-pressure data.
本研究以壓力鍋排水實驗獲取30種土樣的高張力段之水分含量，並以van Genuchten (1980) 建議的 -1500kPa 含水量實測值做為殘餘水分含量。另將θr 視為待定參數，以最佳擬合方式求 取其值，也嘗試用不同的方法求取殘餘水分含量，共計有 8 種方法，分別探討這些方法之實用 性及適用性，以在高張力條件下決定 van Genuchten 模式的θr 參數。結果顯示，將θr值視為 未知參數，直接擬合出的最佳擬合θr 值，能真實地呈現出實驗量測資料的趨勢，也是最為簡 便快速的方法。但是，在缺乏高張力資料的狀況下，輔以土壤水分係數 (MF – 1) 或 USDA – NRCS (2011) 的經驗估算公式來求取殘餘水分含量，能讓所建立的水分特性曲線更能貼近高張 力段實測值。
|Appears in Collections:||第48卷 第04期|
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