南投地區土石流發生潛勢分析

Potential Analysis of Debris Flow Torrents in Nantou Area

謝育樺(Yu-Hua Hsieh)

指導教授 ： 林美聆

國立臺灣大學/工學院/土木工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02769

摘要

在台灣，每年颱風過後皆發生土石災害，而土石流是台灣最嚴重的土石災害之一，如果能將土石流潛勢溪流加以分級，並了解最主要的影響因子，將能對於土石防災與治理有相當大的助益。
本研究搜集南投地區土石流相關資料與土石流重大災害事件，針對被列入92年水保局所公開之1420條土石流潛勢溪流，進行土石流潛勢分析。選取適用之土石流影響因子包括集水區面積、溪流長度、形狀係數、殘土率、溪床平均坡度、邊坡坡度分佈、邊坡坡向分佈與地質種類等八項影響因子進行討論，並建立南投地區非土石流溪流資料，以區別分析探討南投地區之土石流發生潛勢。
本研究所建立之潛勢分析模式有三個，為「潛勢分析模式一」、「潛勢分析模式二」與「潛勢分析模式三」，將南投地區總共199條土石流溪流予以分級為高中低，高潛勢土石流溪流者共有60條，中潛勢土石流溪流共有82條，低潛勢土石流溪流共有57條，分級越高發生土石流機率越大。潛勢分析之結果，影響南投地區之土石流的主要因子為殘土率與地質種類Mj(瑞芳群及其相當地層面積百分比)，而分地質區分析土石流潛勢，較能正確判斷是否為土石流。使用主成分分析能有效將類別項因子萃取，便於區別分析之用。本研究分析土石流潛勢的方式可以作為未來深入研究土石流發生潛勢的參考依據。

關鍵字

南投 ； 土石流 ； 區別分析 ； 影響因子 ； 潛勢

並列摘要

Every year typhoons cause ground disaster in Taiwan, and the debris flow is one of the most serious ground disasters in Taiwan. With grading the of debris flows torrents and understanding of the most main influence factor, it will provide information for disaster reduction management.
This research collects debris flow related data in Nantou and the debris flow major disaster affairs. The debris flow torrents potential analysis was performed based on the 1420 debris flow torrents by Soil-and-Water Conservation-Bureau (2003). Select eight suitable debris flow influence factors that includes basin area, streams length, form factor, hypsometric integral, stream mean slope, slope distribution, slope aspect and geology category etc. were selected Principle Component Analysis was used to extract category item factors, such as slope distribution, slope aspect and geology category, and Discrimination Analysis was conducted for the potential of debris flow torrents in Nantou county.
In this research, three potential analytical mode were proposed as " potential analytical mode one", " potential analytical mode two" and" potential analytical mode three". Given altogether the 199 debris flow torrents in Nantou ratings for high, medium, low. 70 debris flow torrents were classified as the high potential, 79 debris flow torrents as medium potential, and 50 debris flow torrents as low potential, respectively. From the result of the potential analyzes, it appeared that most significant influence factors of debris flow in Nantou region are hypsometric integral and geology category Mj. Results of discriminate analysis of debris flow torrents were improved by taking into account the different geology divisions. Principle Analysis extracted category item factors effectively and made discrimination analysis more convenient.

並列關鍵字

debris flow ； Nantou ； potential analysis ； discrimination analysis ； influence factor

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