| Summary: | 碩士 === 國立宜蘭大學 === 土木工程學系碩士班 === 94 === Due to special environmental aspects such as steep slopes, frequent earthquakes, inferior geological conditions, along with high intensity precipitation and narrow river channels, the stability conditions of Taiwan Island are constantly in critical condition. In addition, the rapid economical development further increased the land usage of slope areas and thus decreased plant coverage of the slopes. Consequently, disasters such as landslides and debris-flows accompanying heavy rainfalls are now rather common in Typhoon season. Among those disasters, debris flows caused severe and direct impact and were the focus of government as well as the people.
Debris flow often occurred at steep slopes and stream beds, formed from loose weathered cover and debris which were contract by the surface runoff and mixed together. Since the speed of debris flows are very fast along with the characters of high impact energy and erosion capability, the influence of debris flow is often catastrophically. Therefore, it is very important to pre-determine the potential debris-flow influenced area and to inform residents in the neighborhood for possible evacuation.
However, since there are 124 listed potential debris-flow creeks along with many other steep streams in Yi-Lan County, it is almost impossible for the government to afford remedial measures for every potential debris flow creek. Therefore, developing a scheme which can determine the level of potential threat for debris flow creeks in advance become an important essay. In this scheme, influences to residents to be secured as well as the environment factors should be considered altogether so as to conform the results of analysis to actual necessity. From the scheme, the government can make decisions based on evaluations consideration both natural factors and human factors and the rescuing resources could be spend more efficiently.
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