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|標題:||Estimation and application of deep-seat landslide in a watershed|
|摘要:||Shiao Lin Village was destroyed seriously during the strike of Typhoon Morakot with long duration and high intensity rainfall. The event not only caused landslides but also resulted in life and property losses. The broad and large-scale landslides occurred in the watershed are difficult to manage. Hence, developing a system to screen the sites and estimate the volume of the landslide in advance is helpful for delineating the landslide potential and area of treatment priority. The risk of landslide can be estimated from the multiplication of watershed vulnerability and torrential hazard. Return period of a rainfall, road development and vegetation status are the crucial factors of a watershed. Soil depth, river concave and/or headwater erosion affect the landslide volume. The Chi-Shan creek watershed was selected to estimate the sites of large scale landslide potential and to verify the factors causing catastrophic disaster in Shiao Lin Village by using the watershed pre-disaster information of 200yr rainfall return period, index of road development, vegetation index, topographic wetness index, index of river concave and headwater erosion. Results show that the sites with high landslide potential are mainly located at the middle and downstream of the watershed which are mostly affected by the spatial distribution of rainfall intensity and degree of road development, while large scale landslides occurring at the sites of headwater. The failures of Shiao Lin Village are coincident with the sites of deep seated landslide estimated by this study. The sites with the characteristics of high landslide potential in probability and scale can be easily extracted using the models established in the study, and could be references of related authorities for decision making in treatment priority and conservation practices.|
小林村於莫拉克風災時，因長延時及強降雨事件造成嚴重災害。不僅產生崩塌亦造成生命 財產損失。集水區之廣泛且大規模崩塌使相關管理單位難以管理，因此透過崩塌區位的篩選及 崩塌量體的推估，將有助於劃定崩塌潛感區位及治理區位的優選。崩塌風險度可由集水區的脆 弱度與危害度相乘推估。以降雨重現期距、道路開發、植生狀況作為集水區之脆弱度。土壤深 度、河道凹岸及向源侵蝕影響崩塌量體。本研究以旗山溪集水區為樣區，利用災前之 200 年重 現期距、道路開發指標、植生指標、地形濕度指數、河道凹岸攻擊及向源侵蝕指標資料推估集 水區高風險及大規模崩塌區位，並驗證小林村大規模崩塌的致災原因。結果發現，崩塌潛勢高 之區位主要受到強降雨分布及道路開發程度影響，其主要分部於集水區中、下游；而大規模崩 塌區位主要分布於源頭區位。小林村災區範圍與本研究所推估深層崩塌區域吻合，因此藉由本 研究成果可篩選出崩塌風險度高且易產生大規模崩塌點位，應可提供優先治理或保全參考。
|Appears in Collections:||第48卷 第03期|
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