DOI: 10.1016/j.epsl.2021.116786
论文题名: Modeling long-term delta dynamics reveals persistent geometric river avulsion locations
作者: Ratliff K.M. ; Hutton E.W.H. ; Murray A.B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 559 语种: 英语
中文关键词: avulsion node
; delta morphodynamics
; river avulsion
; river delta
英文关键词: Banks (bodies of water)
; Floods
; Hydrodynamics
; Location
; Sea level
; Topography
; Water
; Backwater effects
; Channel avulsions
; Coastal process
; Geometric constraint
; Laboratory experiments
; Linear diffusion
; Primary control
; Sedimentary lobes
; Rivers
英文摘要: River deltas grow through repeated stacking of sedimentary lobes, the location and size of which are determined by channel avulsions (relatively sudden changes in river course). We use a model coupling fluvial and coastal processes to explore avulsion dynamics under a range of wave energies and sea-level-rise rates and find that the primary control on avulsion location and delta lobe size in our model is the critical superelevation ratio (SER), the amount of channel aggradation relative to the surrounding floodplain that is required to trigger an avulsion. The preferred avulsion location arises because of geometric constraints – a preferential avulsion node occurs at the break in floodplain slope that develops as the river progrades and/or sea level rises. This concavity develops in our model because the river profile aggrades and erodes via linear diffusion, whereas the diffusion of the floodplain topography is limited to episodic crevasse splays. These results are in contrast to recent modeling work, which was motivated by laboratory experiments and assumes a union between river channel and floodplain aggradation rates, and where avulsion nodes are driven by backwater hydrodynamics. The preferred avulsion length in our model scales well with laboratory, field, and model results without including hydrodynamic backwater effects. This work suggests an alternative mechanism to explain avulsion locations on deltas where floodplain topography aggrades and/or diffuses more slowly than the river channel profile, and it points to the need to elucidate river channel and floodplain connectivity over large space and time scales, and how the connectivity varies from one type of delta to another. © 2021 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165639
Appears in Collections: 气候变化与战略
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作者单位: Division of Earth & Ocean Sciences, Nicholas School of the Environment, Duke University, Box 90230, Durham, NC 27708-0230, United States; Community Surface Dynamics Modeling System, University of Colorado, Campus Box 450, Boulder, CO 80309-0450, United States
Recommended Citation:
Ratliff K.M.,Hutton E.W.H.,Murray A.B.. Modeling long-term delta dynamics reveals persistent geometric river avulsion locations[J]. Earth and Planetary Science Letters,2021-01-01,559