台灣每年平均會受3到4個颱風侵襲，加上近年來的全球氣候變遷加劇，極端降雨事件更加頻繁的發生，土砂災害因此更容易發生。台灣發生的土砂災害，包括土壤沖蝕、地滑、山崩及土石流等，這些災害對於我們的居住安全及財產生命造成很嚴重之威脅，因此災害發生機制的了解以及災害運動行為的預測對於我們而言是十分重要的，若能利用數值模擬的方法來預測土石流的運移行為以及評估土石流可能影響的範圍，使我們於災害發生前就預先獲得土石流的流動情況及可能堆積的區位，讓我們提前防範並採取必要的措施，把災害損失降低，減少經濟損失。
本研究應用Tai et al.(2019)提出的兩相流理論模型，探討Egashira(1993)及Li and Duffy (2011)所提出的侵蝕堆積率，把兩種侵蝕堆積方法進行整合並修正，再加入模式之中，以模擬土石流在運移過程產生的堆積情況，數值方法方面則採用中央差分有限差分法寫成之非震盪之數值方法(non-oscillating central , NOC)來求解淺水波模式之非線性雙曲線方程式。本研究將模擬結果與東京大學堀田紀文教授2017年的大尺度土石流實驗相互比較，討論數值結果與實驗結果的差異性。本研究專注於侵蝕堆積率在土石流模式的適用性，並於參數或侵蝕堆積條件的改變之中尋找最合適的土砂侵蝕堆積模式。

Typhoons will hit Taiwan three to four times per year on average. In addition, the global climate change has intensified in recent years. Extreme rainfall events have occurred more frequently, and soil sand disasters are more likely to happen. Sediment hazards in Taiwan, including soil erosion, landslides and debris flows, which pose a serious threat to our residential safety and property. Therefore, the disaster mechanism and the prediction of disaster movement behavior are very important for us. If we can use numerical simulation methods to simulate the sequential flow behavior of debris flow and to assess the range of possible impact area of debris flow, we can obtain the information of flow behavior and the possible location of sediment deposition before the disaster happened, and take precautions and necessary measures to reduce disaster losses and economic losses.
In present study, the two-phase flow theoretical model proposed by Tai et al. (2019), was used to investigate the Appropriateness of erosion rate proposed by Egashira (1993) and Li and Duffy (2011). The two erosion methods were integrated and amended, and then added the method into the model, thus we can simulate the erosion and deposition of the debris flow during the flowing process. The numerical method used the non-oscillating central scheme (NOC) consist of central finite difference method to solve the partial differential equation of shallow water model. The present study compares the simulation results with the debris flow experiment which conducted by Professor Hotta of the University of Tokyo in 2017 to discuss the difference between numerical results and experimental results. The present study focuses on the applicability of erosion method in the debris flow model, and finds the most suitable debris flow model.

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