https://scholars.lib.ntu.edu.tw/handle/123456789/40861
標題: | 行政院國家科學委員會專題研究計畫成果報告-中橫公路崩山災害研究 | 作者: | 林俊全 | 關鍵字: | DTM;Landslides evolution;Central Cross Island Highway;數值地形模型;崩塌地演育;中橫公路 | 公開日期: | 2005 | 出版社: | 臺北市:國立臺灣大學地理環境資源學系暨研究所 | 摘要: | It is well-established that landslides are extensively triggered as a result of large seismic events in upland areas. These landslides are known to release sediments into the fluvial system, although there is contradictory evidence about how quickly this makes its way into the main channels. Some authors have postulated that sediment moves through the drainage system as a ‘slug’, whilst others have noticed only limited impact as material remains stored in the drainage basin. What has almost never been addressed is the continued evolution of the landslides themselves after the seismic event, and their continued role in releasing slope materials. This paper examines the Tachia River basin in western Taiwan, which was extensively affected by landslides during the 1999 Chi-Chi earthquake. Using vertical cartographic aerial photographs and satellite images, this study demonstrates that the area affected by landslides increased substantially after the main earthquake as a result of high intensity rainfall events. Analysis of suspended sediment data from downstream of the area affected by landslides, show that sediment concentration steadily increases with time, in the period after the initialization of slope movements. A simple model in which sediment production increases immediately after the earthquake and then steadily reduces through time appears to be over simplistic, and should be replaced by a model that incorporates complex responses to the initial and subsequent events. 台灣位於歐亞大陸板塊與菲律賓海板塊的聚合帶上,地震與構造運動頻繁,地表上升速率高,加上高颱風、豪雨和降雨量,地表的地形作用劇烈, 塊體運動( mass movement)經常發生,對於社會與經濟方面有許多影響。1999年的九二一大地震在台灣 中部地區形成許多大規模的新崩塌地,這些崩塌地成為地表地形作用之一,原本穩定的地區成為亞穩定或不穩定狀態,在之後的桃芝颱風及敏督利颱風降雨的影響下,成為非常不穩定的地區之一,崩塌地持續發育。 事實上,中部橫貫公路西段,從谷關至德基水庫路段,在九二一地震之中遭受嚴重損害,這是受到地震所產生的塊體運動而形 成的邊坡不穩定現象。原本的路基在許多路段已經完全消失,大量崩積物沿著邊坡滑落至河谷,進入大甲溪成為河川搬運的物質,崩塌地也隨著時間而演育。 因此本研究希望以地形學的角度來分析中橫公路西段沿線的邊坡崩塌現象,試圖瞭解地形因子在崩塌中所扮演的角色。從航照和衛星影像,說明了發生山崩的地區在地震之後的豪雨事件裡大量增加。另外,分析懸移質沈積物資料,顯示沈積物已經穩定地隨 著時間增加。因此,從地震後沈積物量的增加以及之後隨著時間穩定的減少的模式看似乎過與簡化,應該一併討論最初和隨後事件複雜反應的模式。 |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/11439 | 其他識別: | 932116M002033 | Rights: | 國立臺灣大學地理環境資源學系暨研究所 |
顯示於: | 地理環境資源學系 |
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932116M002033.pdf | 1.7 MB | Adobe PDF | 檢視/開啟 |
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