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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 112,
C12015,
doi:10.1029/2007JC004101,
2007
Tidal asymmetry and residual circulation over linear sandbanks and their implication on sediment transport: A process-oriented
numerical study
Rosario Sanay
Marine Science Program, Department of Geological Sciences, University of South Carolina, Columbia, South Carolina, USA
George Voulgaris
Marine Science Program, Department of Geological Sciences, University of South Carolina, Columbia, South Carolina, USA
John C. Warner
U.S. Geological Survey, Woods Hole, Massachusetts, USA
Abstract
A series of process-oriented numerical simulations is carried out in order to evaluate the relative role of locally generated
residual flow and overtides on net sediment transport over linear sandbanks. The idealized bathymetry and forcing are similar
to those present in the Norfolk Sandbanks, North Sea. The importance of bottom drag parameterization and bank orientation
with respect to the ambient flow is examined in terms of residual flow and overtide generation, and subsequent sediment transport
implications are discussed. The results show that although the magnitudes of residual flow and overtides are sensitive to
bottom roughness parameterization and bank orientation, the magnitude of the generated residual flow is always larger than
that of the locally generated overtides. Also, net sediment transport is always dominated by the nonlinear interaction of
the residual flow and the semidiurnal tidal currents, although cross-bank sediment transport can occur even in the absence
of a cross-shore residual flow. On the other hand, net sediment divergence/convergence increases as the bottom drag decreases
and as bank orientation increases. The sediment erosion/deposition is not symmetric about the crest of the bank, suggesting
that originally symmetric banks would have the tendency to become asymmetric.
Received 12
January
2007;
accepted 17
September
2007;
published 22
December
2007.
Keywords: tidal sandbanks;
residual flow;
net sediment transport.
Index Terms: 4255 Oceanography: General: Numerical modeling (0545, 0560); 4219 Oceanography: General: Continental shelf and slope processes (3002); 3022 Marine Geology and Geophysics: Marine sediments: processes and transport; 4560 Oceanography: Physical: Surface waves and tides (1222).
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 898716 bytes)
Citation: Sanay, R., G. Voulgaris, and J. C. Warner
(2007),
Tidal asymmetry and residual circulation over linear sandbanks and their implication on sediment transport: A process-oriented
numerical study,
J. Geophys. Res.,
112,
C12015,
doi:10.1029/2007JC004101.
Copyright 2007 by the American Geophysical Union.
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