應用證據權重法評估土石流發生潛勢－以高屏溪流域為例

The Use of a Weight of Evidence Approach to Determine the Potential for the Occurrence of Debris-Flow in the Gaoping River Basin

何秋燕(Chiu-Yen He) ； 詹錢登(Chyan-Deng Jan) ； 楊斯堯(Ssu-Yao Yang)

《中華水土保持學報》 48卷2期 (2017/06) Pp. 92-100

https://doi.org/10.29417/JCSWC.201706_48(2).0004

摘要

本研究使用證據權重法探討集水區地文因子與土石流發生之關係，從而判別土石流發生之可能性。證據權重法利用勝算及勝算比計算各地文因子對土石流發生影響的權重值，然後以線性疊加方式建立土石流發生評估地文潛勢指標 (SI)，某集水區的SI 值愈大表示該集水區土石流發生的潛勢愈高。以高屏溪流域2005至2012 年間土石流事件為例，計算各土石流事件集水區的SI 值，並透過成功率曲線 (AUC) 的方法進行驗證，有土石流發生的集水區所對應之AUC 皆落於0.7-0.9 之間，顯示本研究所建立之地文潛勢指標能夠相當成功地推估土石流發生潛勢。

關鍵字

土石流 ； 證據權重法 ； 地文因子 ； 地文潛勢指標

並列摘要

This study uses the weight of evidence method (WEM) to determine the relationship between the physiographical factors and the occurrence of debris flow, in order to determine the potential for the occurrence of debris flow. The chances and their ratios are used in a WEM to determine the weighting factors for 12 physiographical factors that relate to the occurrence of debris flow. The linear sum of 12 weighting factors forms an integrated physiographical susceptibility index (SI). The higher the value of the SI for a watershed, the greater is the potential for debris flow. Debris flow events that occurred in the Gaoping River Basin (GRB) from 2005 to 2012 are studied using WEM in this study. The SI-values for debris-flow-stream watersheds are calculated and ranked to produce successive rate curves. The area under the successive rate curves (AUC) in GRB is then calculated for 8 severe rainfall events during this period. The result shows that the values for the AUC are between 0.7 and 0.9, so WEM and the proposed-SI accurately predict the potential for the occurrence of debris flow.

並列關鍵字

Debris flow ； Weight of evidence ； physiographical factors