| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 87 === Debris flow has gradually made serious damage during these ten years. It is fact that people is eager to know how to prevent the damage of debris flow. The Pakua platform is located at the west side of central Taiwan island and the total area is about 219 Km2. There are many populous towns surrounding this area. Because of younger geologic strata and bad condition in rock glue, a lot of gullies were developed in this area. Debris flow is also one of reoccurring geological hazards and it has made terrible damage in this area before. Thus, it''s required to evaluate the torrents that exist potential danger of debris flow. By this way, we can know the distribution of the potential dangerous torrents in advance.
The evaluation for the potential dangerous torrents of the debris flow is the basis of anti-disasters and the necessity for planning and constructing control works to prevent the debris flow disasters. Due to the investigation from real spots, we use theoretical formula to analyze and research the distribution and dangerness of the torrents in the area. Considering the practical conditions, we use two indexes, that are the dangerness of happening and the dangerness of people''s lives and properties loss, to compare each torrent in different period of rainfall frequency. Then, we can evaluate the dangerness for each torrent.
According to the analysis, the potential dangerous torrents of debris flow exist from Yuan-Lin to Erh-Shui where are located on the west side of Pakua platform and debris flow actually occurred before. Among the 40 dangerous torrents, there are 92.5﹪will probably occure debris flow in 5 years period of rainfall frequency. In addition, the torrents in 25 years period of rainfall frequency will probably occure debris flow, but only a small scale hazard and there are two torrents that in 50 years period of rainfall frequency will occure a large scale hazard.
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