和社溪上游河段因位處深山，如以傳統方式施設河床運輸便道， 其施作成本及維護難度過大，對於疏濬執行確有困難且成效亦受限制；若 改採動床模式新技術將瓶頸段、具保全對象河段等辦理疏通，可能有事半 功倍效益。因濁水溪上游集水區内仍有甚多土石位於邊坡上，此部分土砂 可能再隨下次颱風豪雨沖刷而下又推積於河床，故本研究擬建立動床數值 模擬之各項邊界條件、參數檢定及驗證，並模擬上游河道疏濬後，分析其 對下游河川影響及減災之效果。

To construct the acces or transport road in the upper watershed for those rivers authorized by central government are usually not available because the location of the rivers are often within the mountain areas. Considering the construction cost, dredging technique, and low engineering efficiency, only those reaches with severe sediment could be dredged . However, large amounts of unstable rocks and soils still stay in the upper watershed and could be transported to the downstream after typhoon or heavy rainfall events. Therefore, the necessary model boundary conditions were given first. After model calibration and validation, the result of bed morphology after artificial dredging is simulated. Then its effectiveness for disaster decrease in the downstream is assessed.