草嶺崩坍及堰塞湖處置評估

草嶺堀畓山於民國88年921大地震作用下，再度發生大規模崩山事件，崩塌土石阻斷清水溪於上游形成堰塞湖（新草嶺潭），崩塌發生時正處於豐水期間，新草嶺潭水位急速上升，經濟部水利處為掌握草嶺殘坡及崩塌土體的安定狀況及新草嶺潭在洪水作用下的安全課題，另鑑於本區水文條件惡劣，必須進行緊急處置，乃在地震後儘速進行緊急處置評估，以作為短期處理方案的依據，另作為長期處理方案規劃之參考。緊急處置評估係依本區水文、水理、地質、環境特性，崩塌及現地調查、資料判讀及利用大地工程，大壩工程，水利工程學理及實務等進行，主要目標針對崩塌區天然土體，草嶺殘坡進行安定分析，評估新草嶺潭潰決所產生之風險，新草嶺潭水資源利用之潛勢及地震後緊急處置方案的評估。本文針對處置評估結果介紹，並對未來草嶺崩塌區及新草嶺長期處置方向提出建議，以供決策單位參考。

關鍵字

921集集大地震；草嶺；崩坍；堰塞湖；草嶺潭

並列摘要

A large-scale landslide happened again at Tsao-Ling Mountain due to the effect of Chi-Chi earthquake on 21st September 1999, a landslide lake formed at upstream of Chi-Shue Creek after the debris blocked the creek. Because the event occurred in flood season, the water level raised up rapidly. In order to understand the stability of residue slope and felled debris and the safety problem of new Tsao-Ling Lake under the effect of flood, also the hydrological condition in this area is severe which made the disposal of natural dam becoming an urgent issue, the Agency of Water Conservancy of Department of Economy proceeded an emergent assessment immediately after the earthquake. The result provided a work guide in short-term and a reference in long-term disposals.Emergent assessment was proceeded based on the characteristics of hydrology, hydraulics, geology and environment of the study area, also with the field investigation, theoretical and practical aspects from geotechnical, dam, hydraulic engineering etc. The major tasks included the stability analysis of natural dam and residue slope, the risk assessment of dam-break flow, the potential usage of water resource and the emergent disposal after the earthquake. This article is to introduce the results of assessment and to propose some suggestions on the long-term disposal of the new Tsao-Ling Lake, which may be a reference for the authorities concerned.

並列關鍵字

921 chi-chi earthquake ； tsao-ling ； landslide ； landslide lake ； tsao-ling lake

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草嶺崩坍及堰塞湖處置評估

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