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Relative importance of fluvial input and wave energy in controlling the timescale for distributary‐channel avulsion
Author(s) -
Swenson John B.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024758
Subject(s) - aggradation , beach morphodynamics , fluvial , geology , avulsion , geomorphology , channel (broadcasting) , sediment transport , bathymetry , sediment , oceanography , engineering , structural basin , electrical engineering
Existing avulsion models are decoupled from nearshore processes. Here, I explore quantitatively how the interplay of wave energy with fluvial input of sediment and water controls the aggradation rate and avulsion timescale of a single distributary channel. My approach rigorously couples a diffusive, moving‐boundary theory of fluvial morphodynamics with a diffusive treatment of shoreface morphodynamics. I use this deterministic model to quantify the time required for channel‐belt superelevation, normalized with channel depth, to attain a threshold value for nodal avulsion at a specified channel location. Increasing the long‐term wave energy relative to fluvial input by an order of magnitude increases longshore sediment dispersal, thereby reducing the rate of channel‐belt aggradation and associated seaward extension and increasing the avulsion timescale by a factor of approximately 50. Far‐field processes eventually limit the ability of wave energy to suppress avulsion.