疏濬對河道沖淤潛勢之影響-以荖濃溪上游為例

當為確保河道排洪能力或保護河川橋樑，利用在適當之位置疏濬是為可能降低沖淤與提昇防洪功能的方法，而疏濬後短期內通常對於河道沖淤與防洪有所幫助，但對於河道未來之沖淤潛勢並且可能影響之範圍是應為積極探討的課題。為達到探討疏濬後河道沖刷、淤積及水理變動之目的，本研究利用NETSTARS擬似二維水理輸砂模式進行模擬，討論因疏濬而產生河道的水理變化、河床高程變化等相關問題。研究範圍主要針對模擬荖濃溪上游河道進行水理輸砂演算，探討在重複發生之洪水歷線下河道之水理變化及泥砂之沖淤。透過本研究之進行了解河川疏濬後之水理與輸砂演變趨勢。結果顯示研究河道在維持現狀的條件下，未來有呈現持續淤積之趨勢，若將研究範圍區分為下、中及上游，則主要淤積段為上游段。由各疏濬方案模擬結果，各段淤積總量的變異性很大，但上游段的趨勢較為穩定，為主要的淤積段。淤積總量之變化主要受到中、下游淤積量變化的影響，其中又以下游的變化情形最大，故疏濬對於疏濬段上游影響較小，反之對下游影響則較為大。

關鍵字

沖淤潛勢； NETSTARS ；疏濬；輸砂

並列摘要

In river management, to ensure the flood discharge capability or protect the bridge, the application of dredging at appropriate place may reduce sedimentation and increase flood protection potential with a short term effect. Thus, it is interesting to explore the sediment deposition potential and its effects due to dredging. By using NETSTARS to simulate sediment transport, this research aims to explore the deposition and the change of hydraulics after dredging. Also, the related issues regarding the change of hydraulic of channel and riverbed elevation by dredging under the ideal conditions are also discussed. This research mainly focuses on the simulation of sediment transport in Laonong River, and the investigation of the change in hydraulics and sedimentation from the historical flood series to explore the tendency of hydraulic and sediment transport after dredging. From the results of this research, it reveals the river channel will continuously maintain as sediment deposition status while the reiver management remains the same as present. And, the study also reveals the main sediment deposition section is in upper stream. The simulation results show that the total sediment deposition varies much in different dredging proposals, however the change in upper stream is more stable, although it is the main sediment deposition section. The variance of sediment deposition is mainly affected by the change of middle, down stream, while mostly from down stream. Therefore, dredging is more effective to down stream, and has little influence to upper stream in terms of sedimentation quantity.

並列關鍵字

deposition potential ； NETSTARS ； dredging ； sediment transport

參考文獻

10.鄭志維、謝慧民、黃煌輝，2007，陡峻河系沖淤演變趨勢模擬的探討分析-以秀姑巒溪為例，第十六屆水利工程研討會，國立聯合大學，第200-207頁。

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