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標題: Evaluation for the Potential Dangerous Torrents of Debris Flow in Pakua Platform
作者: 施東隆
Shih, Dong-Long
關鍵字: 土石流
出版社: 水土保持學系
摘要: 土石流災害於近10年來有益發嚴重之趨勢,使得社會上對於土石流之防災需求也日益殷切。八卦山台地位於本省中部西側,總面積219平方公里,週邊城鎮林立,人口稠密。由於地層生成年代較新,岩石膠結不良,以致沖蝕溝發達,加上本區曾經歷嚴重的土石流災害,而土石流又具有再發生性,因此,對於本區之土石流潛在危險溪流,有必要加以調查分析,以便能預先掌握土石流危險溪流之分佈,作為災害預防之參考。 土石流潛在危險溪流之危險度評估為防災工作之基礎,亦是防災工程治理規劃之必要條件。本研究評估之方式係依據現場調查結果,以現有理論公式來分析、探討本區危險溪流之分佈及其危險度。探討過程中,考量實用需要而將土石流發生之危險性及保全物受災之危險性等二項指標,在不同降雨頻率年雨量下分別評比,最後再綜合評估各溪流之危險度。 研究結果顯示本區潛在危險溪流多數分佈於台地西側員林至二水一帶,而與區內歷年土石流發生地區一致,並且在40條潛在危險溪流中,有92.5﹪在5年頻率雨量時即有可能發生土石流,而在25年頻率雨量時各溪流均有可能發生土石流,但均屬小規模災害之溪流,在50年頻率雨量時則有二條溪流屬於大規模災害之危險溪流。
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.
Appears in Collections:水土保持學系



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