考慮空間與雨量變異之土石流影響因子潛勢分析

Potential Analysis of Debris Flow Torrents Considering Spatial and Rainfall Variations

莊漢鑫(Han-Hsin Chuang)

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(2012年)

https://doi.org/10.6342/NTU.2012.01772

摘要

台灣位處板塊交界帶，造山運動盛行，使得地質破碎複雜。近年來山區開發過當，而邊坡破壞亦多有發生，加上台灣常受到颱風侵襲，其所帶來豪大降雨常導致土石流發生。2008年卡玫基颱風、2009年莫拉克颱風造成台灣南部地區嚴重土石流事件，所以對土石流進行潛勢分析，以了解誘發因子與環境因子對土石流發生之影響。
研究針對2011年水保局公開之全台1578條土石流潛勢溪流，蒐集高雄地區92條潛勢溪流相關資料與災害事件，分別對外在誘發因子與自然環境潛勢因子作土石流發生之探討。以高雄地區土石流潛勢分析為基準，將重要的自然環境影響因子列入考量，以費雪區別分析進行土石流潛勢分析。利用高雄地區所得費雪區別函數預測台南48條潛勢溪流、嘉義62條潛勢溪流；使用熱點分析針對不同降雨參數分析其與災害點位分布之關係。探討誘發因子與環境因子對土石流發生之關係。
本研究從外在誘發因子熱點分析與環境潛勢值合併討論中發現，外在誘發因子對土石流發生有顯著影響，當環境潛勢值介於中潛勢或高潛勢，只要降雨達一定門檻就會形成土石流，而當環境潛勢值較低時，其土石流發生所需降雨條件提高，或是幾乎不會發生土石流，故土石流潛勢分析除環境因子之影響外，降雨誘發條件為引致土石流之重要條件。

關鍵字

土石流 ； 颱風 ； 費雪區別分析 ； 熱點分析 ； 潛勢分析

並列摘要

Taiwan is situated in the junction of tectonic plates, which causes fragile and complex geological condition. In recent years, mountainous areas have been overdevelopment, and slope failures often occur. Moreover, typhoons carrying torrential rainfalls often cause debris flow. Recently, there are two typhoons causing severe debris flow in the Kaohsiung area: Typhoon Kalmaegi in 2008 and Typhoon Morakot in 2009. Therefore, this study focused on the debris flow potential analysis in order to understand the predisposing factors and environmental factors, which affect the occurrence of debris flow.
In our study, debris flow information and disaster events in the Kaohsiung area were collected, based on the 1578 debris flow streams in Taiwan published by Soil and water Conservation Bureau (2011). We investigate torrents of predisposing factors and environmental factors for potential debris flow. Potential torrents analysis of debris flow selected important environmental factors was performed, using Fisher discriminant analysis to analyze potential debris flow. Then the discriminant model based on Kaohsiung is used for prediction of Tainan and Chiayi counties. We used hot spot analysis for investigating the relationship of disaster points and their rainfall parameters. Explore the relationship between predisposing factors and environmental factors on the occurrence of debris flow.
Our study found that the occurrence of debris flow mainly influenced by the predisposing factors, and environmental factors. The rainfall threshold conditions for inducing decreased as debris flow potential increased. Predisposing factors are important conditions for causing debris flow.

並列關鍵字

debris flow ； typhoon ； Fisher discriminant analysis ； hot spot analysis ； potential analysis

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