土石流潛在溪流之危險度的評估方法

A STUDY ON THE DANGER RANKS OF POTENTIAL DEBRIS FLOWS

10.29417/JCSWC.199305_24(1).0002

謝正倫(Cheng-Lun Shieh)；陳禮仁(Li-Jen Chen)

土石流 ； 危險度 ； 有效集水面積 ； Debris Flow ； Dangerous Rank ； Effective Watershed Area

中華水土保持學報

24卷1期（1993 / 05 / 01）

13 - 19

繁體中文

土石流潛在危險溪流之危險度的判定是防災工作之基礎，本文提出以有效集水面積，作爲危險溪流之判定指標，並以流出土砂量作爲危險度之評估標準，將危險度分爲A、B、C三個等級。其中C級可視爲不具危險性者，而A級爲高危險性者。同時進一步推導有效集水面積與土砂流出量間之關係式，使土石流危險溪流之判定指標與危險度間能有一明確關連。最後以本省東部地區爲例，自歷年之土石流誘發暴雨中，選取其中値降雨強度I_(50)作爲計算條件，針對三種危險度計算其有效集水面積。計算結果顯示，相對於低危險性之C級溪流其有效集水面積値，隨溪床坡度而變化，其值在1至8公頃間，由調査顯示本省東部地區，溪流之有效集水面積小於6公頃者，幾乎沒有明顯之土石流發生例，顯示本研究中之C級溪流度，確實具有較低之土石流發生危險性。

Among the protection strategy of debris flow damges, the most basic and important work is to know the distribution of potential danger river of debris flow. The main purpose of this paper is to use the supposed index and criteria for identity on topography maps to judge the danger ranks of each river. The effective watershed area and the quantity of flow-out sediment were presented as the identity index and eriteria in this paper. To take the Hualien county as an example, using the field rainfall data and the duration data of debris flow, the relations between effective watershed area and dangerous rank were calculated. The effective watershed area of low dangerous rank in Hualien county was about 0.01 to 0.08 km^2 which was very similar to the result of field investigation.