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標題: | 陳有蘭溪流域山崩與植生狀態在颱風與地震事件中之對應關係 The relationship between vegetation and landslide-induced by typhoon and earthquake along the catchment of Chenyoulan River |
作者: | I-Hui Chen 陳宜徽 |
指導教授: | 陳宏宇 |
關鍵字: | 陳有蘭溪,植生指標,山崩,生物量,921地震, Chenyoulan River,NDVI,landslide,NDVI,biomass,921-earthquake, |
出版年 : | 2005 |
學位: | 碩士 |
摘要: | 本研究嘗試利用1996年至2004年陳有蘭溪集水區流域的山崩及植生的分布狀態,來探討彼此間的相對應關係。研究方法主要是利用賀伯颱風、921地震、桃芝颱風及敏督利颱風等四個事件的航照圖與SPOT衛星影像對於山崩,以及常態化差異植生指標進行數化分析與圈繪判釋,其中生物量的估算是以台大試驗林與林務局的林班資料為參考依據。地質材料的強度試驗結果,則主要是在探討岩性與山崩的相對應關係。一般而言,本研究區域內崩塌地上的常態化差異植生指標為介於-0.2至0.2之間,生物量的分布為介於50t/ha至350t/ha之間。當常態化差異植生指標增高0.1,植生覆蓋率增加20%,高程每升高1000公尺生物量增加80t/ha至100t/ha之間,此意義顯示集水區內的植生指標越高,植生覆蓋率越好,反之則為植生狀態不好的區域。
從山崩的判釋結果中發現,921地震後之崩塌面積比1996年賀伯颱風後增加了2.6倍,生物量減少3.4倍,植生指標減少0.08。2001年桃芝颱風後崩塌面積比921地震後增加2.1倍,生物量減少1.6倍,植生指標減少0.04。2004年敏督利颱風後崩塌面積比桃芝颱風後增加1.1倍,生物量減少1.2倍。植生指標減少0.09。就崩塌與植生狀態的對應關係來看,921地震後崩塌面積與植生指標有逐漸減少的趨勢,彼此間呈現一個負相關的相對應關係。 就岩石強度及傳波速度與植生狀態的調查結果發現,本研究區域變質岩層的岩石強度介於100MPa至150MPa之間,是南莊層強度的2倍,傳波速度是1.5倍,不連續面密度為2倍,常態化差異植生指標為0.5倍,此結果顯示,常態化差異植生指標和岩石強度、傳波速度及不連續面密度有負相關之對應。 幾次颱風事件中估算之輸砂量為介於0.3Mt至28.7Mt之間,生物量為介於9.4kt至97.4kt之間,此意義顯示,陳有蘭溪在暴雨期間所攜帶大量的沉積物,主要仍以集水區內之地質材料為主,植生作物受沖蝕進入河流內之比例則大約佔有其中的0.36%。 In the study, we are trying to find out the relationship between landslide distribution and vegetation along the catchments of Chenyoulan River from 1996 to 2004. We use SPOT satellite imagines and air photos to map the landslide and analysis the Normalized Difference Vegetation Index of typhoon Herb, 921-earthquake, typhoon Toraji and typhoon Mindulle. We use both the Experimental Forest of NTU and Taiwan Forestry Bureau’s data to estimate the biomass. Using the data from the test of geomaterial to discuss relationship between lithology and landslides. In general, the NDVI values of landslide area are between -0.2 to 0.2, and biomass is between 50t/ha to 350t/ha. When NDVI increases 0.1, vegetation cover rates will add 20%, and elevation increase 1000 meters, biomass add around 80t/ha to 100t/ha. It means when NDVI values increase and vegetation cover rates will add in the same time in this study area. From the mapping of the landslide, we found that in 1999 921-earthquake’s landslide areas are 2.6 times, flux biomass is 3.4 times, and NDVI values decrease 0.08 than typhoon Herb’s. In 2001, typhoon Toraji’s landslide areas are 2.1 times, flux biomass is 1.6 times, and NDVI values decrease 0.04 than 921-earthquake’s. In 2004, typhoon Mindulle’s landslide areas are 1.1 times, flux biomass is 1.2 times, and NDVI values decrease 0.09 than typhoon Toraji’s. It is say that landslide areas have the negative relation with NDVI. From the result of rock strength, sonic wave test and vegetation, we can find out metamorphic rock strength is between 100MPa to 150MPa. Rock strength and sonic wave test are 2 and 1.5 times than Nanchuang formation. Discontinuities and NDVI values are 2 and 0.5 times than Nanchuang formation. According to the result, NDVI values have negative relation with rock strength, sonic wave test and discontinuities. In several typhoon events, sediment discharge is from 0.3Mt to 28.7Mt and biomass is from 9.4kt to 97.4kt. It means in rainfall most sediment is from the geomaterial rather than vegetation. Because vegetation is only 0.36% of sediment discharge. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/36705 |
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