土壤沖蝕係指土壤受外力作用,自固結土體產生分離、搬運及淤積等現象。由於現今的資料數量有限,因此土壤沖蝕研究是必要的。本研究針對臺灣北部地區不同土壤分類設置17處研究試區,進行現地土壤沖蝕量測,從民國99年5月至101年10月止,共觀測717筆資料進行研究與分析。 依據水土保持手冊查得鄰近試區地點之Km值;現地採取土樣依據手冊所列出試驗項目,由ASTM試驗規範得到實驗Km值;盧光輝(1997)由土壤質地代碼所得到Km值及通用土壤流失公式(USLE)反推現地觀測Km值相互比較,探討四種Km值的適用性。 從結果得到北部地區各種土壤分類之Km值,各種Km比較結果得知,USDA分類所得同類土壤,其實驗Km值較為接近由現地觀測反推之Km值,行政院農委會之土壤分類法,壤土類亦具此趨勢,然沖積土與石質土之現地觀測反推Km值與查表值較接近。
Soil erosion refers to the soil particles separated from the deposits by external forces and followed by transportation and sedimentation processes. Due to limitation of data obtained in the past, it is necessary to study the soil erosion. This study focuses on the areas in northern Taiwan and sets 17 experimental areas to investigate different soils and measure their eroded length and depth in situ. The study collates 717 data to be analyzed from May 31, 2010 to October, 2012. To compare and discuss the feasibility of Km, four types of sources in searching Km are used. The sources are: 1) the Km of nearness of the experimental area obtained from Water-and-Soil-Conservation handbook based on the, 2) the experimental Km by cooperating empirical equations in the Water-and-Soil-Conservation handbook and test results of soil sample in the experimental area, which follows the ASTM standards, 3) the Km based Lu, Guang-hui(1997)'s "Soil Texture Code", and 4) the Km back-calculated by using Universal Soil Loss Equation(USLE). The results show that, in northern Taiwan, the experimental Km values of different types of soil, under USDA soil classification, are close to the back-calculated Kms. Loamy soils, in the Council of Agriculture, Executive Yuan's soil classifications, have the same approaches. However, the Kms of alluvial soils and stone soils are comparable to the Kms obtained from Water-and-Soil-Conservation handbook.