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標題: 以動床實驗探討土石流入匯主流之沖積扇形貌與內部變化
Debris Flow Fan Morphodynamics at a Confluence in a Mobile Bed Channel
作者: 許修銓
Hsiu-Chuan Hsu
關鍵字: 土石流沖積扇
debris fan
dimensional analysis
digital image analysis
mobile bed
引用: 1. 陳樹群(1999),「堰塞湖潰決機制與減災工法研究」,中華水土保持學報,30(4):299-311 2. 陳樹群、彭思顯(2003),「應用數位影像處理於主支流交會實驗之量測」,中華水土保持學報,34(2):195-205 3. 陳樹群,彭思顯(2004),「高含沙支流入匯主流形成之沖積扇型態」,第四屆海峽兩岸山地災害與環境保育學術研討會論文集,台北,pp.259-265 4. 陳樹群,李仲強(2006),「土石流支流入匯主河道之泥沙沖淤研究」,中華水土保持學報,37(1):9-22 5. 陳樹群,安軒霈(2006),「土石流入匯主流形成沖積扇型態之渠槽實驗」,中華水土保持學報,37(3):317-326 6. Chen, R. D., X. N. Liu, S. Y. Cao, and Z. X. Guo (2011), Numerical simulation of deposit in confluence zone of debris flow and mainstream, Sci. China Technol. Sci., 54(10), 2618–2628. 7. Chen, S. C., and S. H. Peng (2006), Two‐dimensional numerical model of two‐layer shallow water equations for confluence simulation, Adv. Water Resour., 29(11), 1608–1617. 8. Chen, S. C., S. H. Peng, and H. Capart (2004), Morphology of alluvial fans formed by hyperconcentrated tributaries, in Proceedings of the 2nd International Conference on Fluvial Hydraulics, Napoli, Italy, edited by M. Greco, A. Carravetta, and R. Della Morte, pp. 1095–1102, Taylor and Francis Group, London, U. K. 9. Dang, C., P. Cui, and Z. I. Cheng (2009), The formation and failure of debris flow‐dams, background, key factors and model tests: Case studies from China, Environ. Geol., 57, 1901–1910. 10. Delorme, P., Voller, V., Paola, C., Devauchelle, O., Lajeunesse, É., Barrier, L., and Métivier, F.(2017): Self-similar growth of a bimodal laboratory fan, Earth Surf. Dynam., 5, 239-252,, 2017. 11. Iverson, R. M. (2013), Mechanics of debris flows and rock avalanches, inHandbook of Environmental Fluid Dynamics, edited by H. J. S. Fer-nando, vol. 1, pp. 573–587, CRC Press, Boca Raton, Fla. 12. Clarke L, Quine TA, Nicholas A (2010), An experimental investigation of autogenic behavior during alluvial fan evolution, Geomorphology, 2010, Vol.115(3), pp.278-285 13. Stancanelli L.M., Lanzoni S., Foti E. (2014), Mutual Interference of two Debris Flow Deposits Delivered in a Downstream River Reach, J. Mater. Sci., 11(6):1385-1395 14. Stancanelli L.M., Lanzoni S., Foti E. (2015), Propagation and deposition of stony debris flows at channel confluences, Water Resour. Res., 51,5100-5116 15. Reitz, M. D. and Jerolmack, D. J.(2012), Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth, J.Geophys. Res.-Earth, 117, F02021 16. Takahashi, T. (1991), Debris Flow, 165 pp., A. A. Balkema, Brookfield, Wis. 17. Takahashi, T. (2007), Debris Flows: Mechanics, Prediction and Countermeasures, Proc. Monogr. Eng. Water Earth Sci., Taylor and Francis, Leiden. 18. Whipple, K. X., Parker, G., Paola, C., and Mohrig, D.(1998) Channel dynamics, sediment transport, and the slope of alluvial fans: Experimental study, J. Geol., 106, 677–694
摘要: 支流兩次性土石流挾帶土砂匯入動床主流,使土石流沖積扇逐漸擴張的過程分為三個階段:第一次土石流中的擴張期及穩定期及第二次土石流的持續發展期。 且利用數位影像分析技術,間隔攝影支流土砂在主流動床上形貌發展階段的過程,並建立不同階段的主、支流數值地形及將實驗最終沖積扇地形切開成半圓的堆積剖面,觀測內部土砂堆疊的變化及互動方式。 將前、後兩次土石流最終沖積扇形貌應用本研究中的無因次分析方法,發現在主、支流皆為固定的單寬流量下,沖積扇形貌皆會有以相似性的形貌持續擴展。且在最窄主流寬度的渠道中,因河道的束縮效應下,主要淘刷位置在大主流流量的土石流事件中,最終的主要刷深位置較小主流流量更往下游的區位發展。而藉由兩次性的土石流沖積扇的半圓形剖面,可將土石流分為三個部分:下游土砂堆積區、中游主流淘刷區及上游土砂落淤區,說明土石流內部土砂堆積的形態變化。 經本實驗的研究發現,動床與土石流沖積扇的互動將影響土石流在主流上形貌的發展及剖面內部土砂堆疊的形態,且在土石流匯入主流後,動床河道能清楚地呈現土石流對於主流底床的影響。
River channel confluences play a crucial role in the dynamics of rivers. In this study, the influence of debris flow introduced in a main channel by a tributary is investigated. The debris fan is divided into three stages; expansion, stable and continuous development. Morphological changes were captured by a laser scan and analysed by MATLAB image analysis toolbox. Additionally, sediment profiles of the debris deposits in the main channel were studied by cutting a semi circle of the debris fan. Dimensionless analysis indicated that all debris fan had similar shape when the main channel and the tributary were fixed. In the narrowest main channel width (due to the debris), erosion occurred farther downstream of the channel. The semi circular section of the alluvial fan showed three regions; downstream deposition, middle stream erosion and upstream deposition areas. This describes the morphological changes in the lateral direction. The study has shown the significant impacts debris flow has on the main channel morphology and sediment deposit profiles
文章公開時間: 2020-08-30
Appears in Collections:水土保持學系



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