圖書典藏及影音數位平台

莫拉克颱風災後集水區內崩塌土石流入河川、野溪及水庫，在行政院核定之「加強河川野溪及水庫疏濬方案」（98.11～101.08）由中央各部、會及縣、市政府通力合作之下，已完成約2.5億立方公尺淤積土石之清除。惟中央管河川上游河段因位屬深山，如施設河床運輸便道，施作成本及難度過大，執行疏濬困難，且成效有限，故仍以瓶頸段、具保全對象河段辦理疏通為原則。然中央管河川上游集水區內仍有大量之土石位於山坡地上，可能再隨颱風豪雨沖刷而下，故中央管河川上游河段淤積土石恐不應單純以疏通方式辦理，爰成立本計畫研擬相關處理對策。

Abstract 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. As a result, those deposited sediment should not be treated only with dredge approach. This project draw up relative disposal approaches to improve the sediment problem. The result of the project items is list as follow: 1. Completeing fundamental data collection from the upper watersheds of Huoshui River and Zengwun River governed by the central government after Morako Typhoon event. The unstable sediment transportation, distribution, and the volume change of sediment were analyzed. 2. Watershed sediment delivery computation and analysis: Before constructing a suitable model to quantify sediment budget , model calibration and validation were conducted. Then, to make the data readable and visualizable, Geographic Information System was used. 3. Movable bed numerical simulation and analysis in the upstream reaches: 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. 4. Impact assessment of stream disposal approaches to downstream channel treatment and disposal prevention. Using sediment budget model to discuss the impact of sediment yields simulated with different scenarios to the downstream river qualitatively and qualitatively. 5. Impact assessment and disposal strategy evaluation for the deposited sediment from the upper of the Huoshui River and Zengwun River to the down reaches: three parameters ; unstable sediment stayed rate, landslide rate and protected objects were taken into accounts and combined with sediment budget model to construct a corresponded consequential rank classification and suitable disposal strategy. 6. Expected benefit for of sediment disposal strategy of the Huoshui River and Zengwun River: according to the former results and corresponded sediment conditions from the upper stream, the disposal strategy and the benefit assessment method were establish.