土石流數值模式於土石流防災上之應用

台灣屬於海島型國家，地形在世界上是小型島嶼，但是海拔卻比許多大陸還要高，屬於短小海拔又高的台灣，因為陡峭的山脈，再加上台灣在颱風頻繁出現的太平洋上，導致大量雨水在一夕之間湧入台灣，造成嚴重的土石流災害，對台灣的居民有嚴重的生命和財物損失，因此，要怎麼降低台灣的土石流災害損失，已經到了非常緊急的時刻。本研究使用Debris-2D數值模式模擬出土石流潛勢溪流防災需要之資訊，搭配基本資料與歷史研究等資料，以新北市新店區屈尺里為例，模擬出土石流防災整合式工作中的土石流潛勢溪流的影響範圍、疏散避難圖與整治工法前後模擬之成效顯現。土石流潛勢溪調查中從調查申請一直到現場勘查，最後到整治工法等動作，依前人研究之方法，大多都是以經驗公式來做模擬土石流範圍的評估，但是因政府人力與資金的限制與不足之下，許多地區溪流大多都是在等待調查的狀態下，在下一次災害來臨前都是暴露在危害之中，本研究應用數值模式應用在土石防災上之應用，使用數值模式在土石流潛勢評估、避難疏散路線、整治工法之建議及成效顯現，可以彌補政府因資金與人力的不足，來達到有效及較低成本的防災功能。

關鍵字

土石流防災； Debris-2D數值模式

並列摘要

Due to typhoons and heavy rains in summer, debris flow has become one of the most severe slope disasters in Taiwan and caused great casualties and property losses every year. The velocity, depth and hazard zone of debris flow are the common uncertainties during planning any countermeasures for disaster prevention. Therefore, we have developed a numerical model, Debris-2D, to simulate the in-situ debris flows. By defining the boundary layer of debris flows as region with stress greater than the yield stress and under the long wave assumptions, the governing equations are derived (Huang, 2003). Adams-Bashforth third order scheme is used as time stepping method and both central difference and upwind schemes are used for space discretization. This numerical model is verified with analytical solutions, laboratory flume tests and many in-situ debris flow disasters occurred in Taiwan and other countries, which shows good results and provides practical information for debris-flow hazard reduction. In this thesis, a case study in Chu-Chi, where a debris flow occurred during Typhoon Nari in 2001, shows how Debris-2D can be applied in debris-flow hazard zone mapping, assessment of engineering treatment, planning of evacuation route, and setup of warning systems. Same procedures can be used to other area prone to debris flows.