DOI: 10.1002/2017JF004350
Scopus记录号: 2-s2.0-85040673288
论文题名: Control of Delta Avulsion by Downstream Sediment Sinks
作者: Salter G. ; Paola C. ; Voller V.R.
刊名: Journal of Geophysical Research: Earth Surface
ISSN: 21699003
出版年: 2018
卷: 123, 期: 1 起始页码: 142
结束页码: 166
语种: 英语
英文关键词: avulsion
; bifurcation
; bypass
; delta
; downstream
; sink
英文摘要: Understanding how fluxes are partitioned at delta bifurcations is critical for predicting patterns of land loss and gain in deltas worldwide. Although the dynamics of river deltas are influenced from both upstream and downstream, previous studies of bifurcations have focused on upstream controls. Using a quasi-1-D bifurcation model, we show that flow switching in bifurcations is strongly influenced by downstream sediment sinks. We find that coupling between upstream and downstream feedbacks can lead to oscillations in water and sediment flux partitioning. The frequency and initial rate of growth/decay of the oscillations depend on both upstream and downstream conditions, with dimensionless bifurcate length and bypass fraction emerging as key downstream parameters. With a strong offshore sink, causing bypass in the bifurcate branches, we find that bifurcation dynamics become “frozen”; that is, the bifurcation settles on a permanent discharge ratio. In contrast, under depositional conditions, we identify three dynamical regimes: symmetric; soft avulsion, where both branches remain open but the dominant branch switches; and full avulsion. Finally, we show that differential subsidence alters these regimes, with the difference in average sediment supply to each branch exactly compensating for the difference in accommodation generation. Additionally, the model predicts that bifurcations with shorter branches are less asymmetric than bifurcations with longer branches, all else equal, providing a possible explanation for the difference between backwater length distributaries, which tend to be avulsive, and relatively stable mouth-bar-scale networks. We conclude that bifurcations are sensitive both quantitatively and qualitatively to downstream sinks. ©2017. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114782
Appears in Collections: 气候减缓与适应
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作者单位: Department of Earth Sciences, University of Minnesota, Twin Cities, Minneapolis, MN, United States; Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Twin Cities, Minneapolis, MN, United States
Recommended Citation:
Salter G.,Paola C.,Voller V.R.. Control of Delta Avulsion by Downstream Sediment Sinks[J]. Journal of Geophysical Research: Earth Surface,2018-01-01,123(1)