為進行土石流災害現象評估及防、減災規劃，根據土石流特性，對土石流潛勢溪流進行系統性的分類有其重要性。由於目的不同，過去的研究對於土石流提出了許多不同的分類方法，然多數分類方式多未能針對土石流災害特性進行分類。本研究利用經濟部中央地質調查所委託之土石流潛勢溪流調查成果，進行土石流潛勢溪流分類，並利用三峽、鹿谷與東勢三個區域進行案例探討。研究結果顯示，土石流潛勢溪流地文、水文、地質與土石堆積特性分類，可以顯現該土石流潛勢溪流之特徵。初步分類結果發現台灣土石流潛勢溪流流動特性以非凝聚性為主。另外，土石流潛勢溪流可利用土石流潛勢溪流之坡度、河寬與集水面積組合而成之流速因子作為流速分類之依據。屬於高流速之土石流潛勢溪流，表示危害度較高。同樣的，土石顆粒愈大，代表土石流潛勢溪流之危害度也較高，本研究分析樣本中共計有275條屬於巨礫型，巨礫型土石流潛勢溪流其下游之工程規劃或土石流防減災工程規劃，均應考慮巨石之危害。本研究建議可根據土石材料堆積比以及崩塌面積比做為土石流潛勢溪流活動度分級之參考，於分析樣本中，共有28條屬於高活動度土石流潛勢溪流。根據屬於集集地震重建區之鹿谷與非重建區之三峽土石流潛勢溪流活動度分級結果，可以清楚發現重大地質事件對土石流活動之影響，隨崩塌以及土石累積之變化，活動度也會隨之變化，故土石流潛勢溪流活動度之分級應隨環境變化而為一動態指標。 Debris-flows classification is very important for hazards mitigation. Based on different purpose, the potential streams of debris flow have been classified as different categories. This research set up a systemic categorised way by using potential streams of debris flow investigation result form Central Geological Survey, MEOA. Three areas, Lugu, Sansia, and Tungshih, were selected as a study area. According to the analysis result, every debris flow can be characterized by hydrology, geology and deposit characteristics. Most of Taiwan’s potential streams of debris flow are non-cohesive. In addition, this research suggested a velocity index which consider the drainage area, stream slope and width. A high valure of velocity index represent a high endanger degree. Similarly, the bigger grain size of debris, the largger damage it might induce. There are 275 potential streams of debris flow belong to block category which need to be considered before planning the debris flow harzad mitigation project. In this research, we propose the activity of debris flow canbe classified by landslide area and deposition ratio. 28 potential streams of debris flow were classified as high activity potential streams of debris flow. According to the debris-flows classification result of Luku and Sansia, it is clearly that the important geology events(Chi-Chi earthquake) make a influence of the activity of debris. Consequently, the avtivity of debris flow should be changed with the variation of landslide and deposition of debris.
