徐美玲2006-07-252018-06-282006-07-252018-06-282000http://ntur.lib.ntu.edu.tw//handle/246246/11370本研究在蘭陽溪上游夫布爾階地上選 取觀測實驗區，收集自民國八十七年底至 八十九年七月的降雨事件和四個觀測孔三 個深度的土壤含水量的變化資料，並分析 其中的43場降雨事件的總雨量、平均降雨 量、最長連續雨時、最大連續雨量和最大 平均時雨量等降雨特性，和各場降雨發生 前後各觀測孔三個深度的土壤含水量的變 化。初步分析發現在同一場降雨事件下， 各觀測孔的土壤含水量變異甚大，因此根 據各場降雨事件所對應的土壤含水量變化 的明顯程度，將降雨事件分為有明顯變化 和無顯著變化兩類。然後比較兩類降雨事 件中各降雨特性間的差異，並進行t檢定， 結果發現能夠讓四孔的土壤含水量發生明 顯變化的各場降雨的平均雨量、最大連續 雨量和最大平均時雨量都比未能造成反應 者來得大，而且均具有統計上的顯著差異 性。各觀測孔不同深度的土壤含水量在各 場降雨事件下的反應並不一致，可能與局 部土壤組成、結構或生物活動狀況有關。 研究顯示連續16天沒雨會造成本階地土壤 的乾涸，而長時間的降雨和較高的最大平 均時雨量可能是造成各層土壤飽和的重要 條件。建議未來可以針對當地造成崩塌的 降雨事件，進行延時和最大平均時雨量的 分析，或能歸納獲得影響階地邊坡穩定度 的降雨閾值。The study site is located upon the Fu- Bu-Ur Terrace at the Lan-Yang His watershed. Rainfall and soil moisture of four observation holes were continuously monitored from 1998 to 2000. 43 rainfall events with good soil moisture data were selected for further analysis. Total rainfall amount, average rainfall intensity, the maximum duration and the maximum rainfall of the within-storm raining periods, and the maximum hourly rainfall intensity of each rainfall events and the corresponding soil moisture variations were compared. The soil moisture fluctuation patterns among different observation holes and among different depths appeared to be extremely complicated. The average rainfall intensity, the maximum duration of the within-storm raining periods and the maximum hourly rainfall intensity of the rainfall events which significantly raised soil moisture were statistically greater than those of the other rainfall events. Variability in soil moisture responses among different observation holes and depths were very likely due to local variations in soil texture, structure and/or bio-activities. The study showed that 16 consecutive rainless days significantly lowered the soil moisture in all observation holes, while long-lasting rainfall or large maximum hourly rainfall intensity seemed to contribute to the saturation of the whole soil columns. Thus, further study of the maximum duration of the within-storm raining periods and the maximum hourly rainfall intensity of the storms which have caused landslides in the study area should be conducted in order to estimate the threshold magnitudes of landslide-triggering storms more effectively.application/pdf31818 bytesapplication/pdfzh-TW國立臺灣大學地理環境資源學系暨研究所階地土壤含水量降雨延時降雨強度terracesoil moisture contentrainfall intensityrainfall durationreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/11370/1/892116M002025.pdf