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Physical linkages between an offshore canyon and surf zone morphologic change
Author(s) -
Hansen Jeff E.,
Raubenheimer Britt,
Elgar Steve,
List Jeffrey H.,
Lippmann Thomas C.
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012319
Subject(s) - canyon , geology , bathymetry , submarine canyon , shore , accretion (finance) , submarine pipeline , surf zone , oceanography , geomorphology , erosion , sediment transport , beach morphodynamics , sediment , physics , astrophysics
The causes of surf zone morphologic changes observed along a sandy beach onshore of a submarine canyon were investigated using field observations and a numerical model (Delft3D/SWAN). Numerically simulated morphologic changes using four different sediment transport formulae reproduce the temporal and spatial patterns of net cross‐shore integrated (between 0 and 6.5 m water depths) accretion and erosion observed in a ∼300 m alongshore region, a few hundred meters from the canyon head. The observations and simulations indicate that the accretion or erosion results from converging or diverging alongshore currents driven primarily by breaking waves and alongshore pressure gradients. The location of convergence or divergence depends on the direction of the offshore waves that refract over the canyon, suggesting that bathymetric features on the inner shelf can have first‐order effects on short‐term nearshore morphologic change.