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題 名 | 鹽化土壤遲滯現象之研究=An Investigation of Hysteresis of Salt-effected Soil |
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作 者 | 馬國宸; 林子雲; 陳主惠; 譚義績; | 書刊名 | 農業工程學報 |
卷 期 | 50:2 2004.06[民93.06] |
頁 次 | 頁23-48 |
分類號 | 434.222 |
關鍵詞 | 鹽化土壤; 遲滯現象; 保水曲線; Hysteresis; Soil-water-retention curve; Salt-effected soil; |
語 文 | 中文(Chinese) |
中文摘要 | 在未飽和土壤水分的傳輸現象中,水分移動的水力特性是相當重要的,此特性取決於土壤含水量及土壤類型等因小,未飽和土壤水分會因乾燥、濕潤交替的歷程而發生遲滯現象,要能準確的計算則必須在乾燥、濕潤歷程交替變化的環境中考慮遲滯現象的發生及其所之變動。臺灣地區四周環海,海水倒灌之情形相當嚴重,此現象困擾著沿海地區之土地利用、土壤復育及農業發展,因為海水中的鹽份在隨水分進入土壤後,其入滲、蒸發及運移之過程十分複雜,且受遲滯現象影響甚巨,也因此更顯未飽和層中水流及鹽份傳輸研究對重要性。 本研究之目標為探討海水倒灌後土壤中水分及鹽份的遲滯現象,以砂箱實驗之方式分析其特性,採用各種濃度之鹽水,進行多組土壤水分遲滯現象研究,藉以觀察鹽份濃度對遲滯行為之影響,由於鹽份溶解於水中,使水的密度增加:就土壤吸水過程中,在相同含水量之狀況下,水密度之改變亦影響空氣進入壓力(air Entry Pressure)之大小,密度較高之鹽水,所需之張力值較淡水為高,因此以鹽水試驗之乾燥曲線亦呈現上移之情形,濃度越高之鹽水,其保水曲線上移之程度越多;並進行數值分析之發展,利用數值模式模擬未飽和層土壤中水分及鹽份之傳輸。鹽份濃度對於土壤水分遲滯現象之影響,包括形狀因子改變,其中以α值與濃度之關係較為明顯,隨濃度之增加呈現逐漸遞減之趨勢,而n值相對於濃度變化,則呈現不規則之改變,若將三種土壤之□、□值分別對濃度進行線性迴歸,可發現其□值均在0.97以上。 |
英文摘要 | In order to solve the transport of water in the unsaturated soil, the hydraulic property must be available, that property is dependent on the moistures and nature of soils. In unsaturated soils, hysteresis is an important phenomenon affecting water flow, and the effect should be taking into account during wetting and drying processes. Taiwan is surrounded with seawater, and it’s very serious that seawater infiltrates into soils. The salinization of soil not only affects the usage of area along the coast, but also influence the restoration of foil and development of agriculture. After the salinity and water infiltrates into soil, the progress infiltrating, evaporating, and movement become very complex. In addition, hysteresis also has a great influence. Therefore, it becomes more important for unsaturated flow and the research of salinity transport. Hysteresis has important for unsaturated flow and the research of salinity transport. Hysteresis has important effects in the field and cannot be neglected. Most studies are ignored about hysteresis because of complication. The prediction of soil water balance can be improved by taking hysteresis into account under diurnally varying environment condition that involved alternative wetting and drying. Under the same water content in wetting curve, salinity water need higher suction into soil pore. Salinity soil water retention curve have been shift upper compared with original soil water retention curve. In drying curve, the changing of water density influences air entry pressure. Water of higher salinity, the soil water retention curve has been shift upper. The changing of salinity cause the changing of α value. We proceeded linear regression of □、□ value, and the R-square value of □、□value exceeded 0.97. |
本系統中英文摘要資訊取自各篇刊載內容。