地文因子對土石流發生影響之研究－以陳有蘭溪為例

Effect of Topographic Factors on Occurrence of Debris Flow - A Case Study of Chen-yu-lan Creek Watershed

林昭遠(Chao-Yuan Lin) ； 張力仁(Lit Chang)

《中華水土保持學報》 31卷3期 (2000/09) Pp. 227-237

https://doi.org/10.29417/JCSWC.200009_31(3).0006

摘要

台灣山區地勢陡峭、地質破碎，加上坡地不當利用的結果，每遇豪雨、颱風侵襲，極易發生土石災害，嚴重威脅坡地居民生命及財產安全。民國85年賀伯風災中，南投縣陳有蘭溪流域土石流災情慘重。本研究選定新中橫公路與陳有蘭溪各支流之交叉點爲評估對象，在足夠的降雨及相同的破碎地質條件下，以DTM資料利用地理資訊系統之空間分析能力，找出影響交叉點發生土石流之因子，利用賀伯風災後SPOT衛星影像與航空照片輔助判釋，以主成份分析做檢測。主成份分析結果顯示三個主成份軸，分別解釋集水區特性因子、坡度因子及形狀因子。集水區特性因子包括集水區面積、河川彎曲度與河溪頻率；坡度因子爲集水區平均坡度與主流平均坡度；形狀因子爲集水區形狀係數。上述地文因子對土石流發生有顯著的影響，可用於土石流危險溪流判定及危險區劃定之參考。

關鍵字

土石流 ； 主成份分析 ； 地理資訊系統 ； 數值地形模型

並列摘要

Owing to steep topography, weak geology, and improper land use, debris flow occurs frequently at the mountain areas where people suffer the disaster of debris flow during typhoon seasons. The Chen-yu-lan Creek watershed was selected to study the effects of topographic factors on occurrence of debris flow. Intersections of roads and streams are the major sites for assessing the impacts of debris flow. Digital terrain model coupled with GIS and RS technologies was used to extract the information, of the watershed. Principal component analysis shows that there are three principal axes, accounting for the factors of watershed characteristic, slope, and form, respectively. These factors have significant influence on the occurrence of debris flow, and are useful for zoning the sites of potential debris flow.

並列關鍵字

debris flow ； principle component analysis ； geographic information systems ； digital terrain model