結合地文與降雨條件以判定土石流發生之研究－以陳有蘭溪集水區為例

Study of Judging Debris Flow Occurrence by Combing the Physiographical Factors and Rainfall Condition Chen-Yu-Lan Stream Watershed as an Example

陳文福(Wen-Fu Chen) ； 李毅宏(Yi-Hong Li) ； 吳輝龍(Huei-Long Wu)

《臺灣地理資訊學刊》 2期 (2005/04) Pp. 27-44

https://doi.org/10.29790/JTGIS.200504.0003

摘要

台灣因地理位置特殊，以致山區地勢陡峭、地質破碎、颱風頻襲，加上部份山坡地被超限利用。因此，每遇颱風豪雨侵襲輒易發生土石災害，嚴重威脅到山區居民生命及財產之安全。位於台灣中部之濁水溪的支流之陳有蘭溪集水區，因數十年前新中橫公路之開闢，加上1999年九二一大地震時最接近震央，均產生了大量之土石鬆方。2001年之桃芝颱風豪雨即發生災情慘重之土石流，其後每逢颱風豪雨來襲時發生土石流之頻率特別高，故以其為探討之對象。
土石流的發生常因集水區內地文狀況的不同，致其發生的條件亦有差異。本研究利用GIS相關技術，分析並整合陳有蘭溪集水區之數位高程模型(DEM)及法國之SPOT衛星影像資料，利用主成份分析法找出影響土石流發生之地文因子，並利用群集分析法找出地文因子較一致之區域將試區予以分類，另外在考慮前期降雨量之情況下進行區別分析，建立陳有蘭溪集水區土石流發生之臨界降雨判別模式。本研究之成果可供防災警戒之參考。

關鍵字

主成份分析 ； 群集分析 ； 區別分析

並列摘要

Due to the special geographical location, Taiwan possesses those natural condition such as: steep topography, cracked and weak geology, and in addition to over land use, so the debris flow occurs frequently at the mountain area when typhoon with heavy rainfall attack Taiwan and those always threaten the safety of people's life and property. The Chen-Yu-Lan-stream watershed is the tributary of Chuo-Sui River in central part of Taiwan, due to the construction of central across high way over twenty years ago and then 921 heavy earthquake occurred in 1999, there produced lots loose earth and rocks. When Typhoon TORAJI attacked Taiwan in 2001, there occurred serious debris flow disaster, and from then on, the occurrence frequency of debris flow has been very high so we took Chen-Yu-Lan stream watershed as the research material.
The different geographic characteristics of various watersheds affect the occurrence of debris flow differently. We used ArcGIS software to analyze and integrate the DEM and SPOT image of Chen-Yu-Lan-Stream watershed, analyze the physiographical factors by GIS techniques and used the principal component analysis and the cluster analysis method to classify Chen-Yu-Lan-Stream watershed, which have the same characteristics. Finally, consider the previous accumulated rainfall to precede discrimination analysis method to establish the discrimination equation on critical rainfall for occurrence of debris flow in Chen-Yu-Lan-Stream watershed. The results of this research can be referred for warning on disaster prevention.

並列關鍵字

principal component analysis ； cluster analysis ； discriminant analysisu

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