Abstract
This study focuses on identifying physical mechanisms that lead to symmetric, tidedominated
ebb-tidal deltas. An idealized morphodynamic model is developed and
analyzed to demonstrate that these deltas can be modeled as morphodynamic equilibria
(no evolving bathymetry). It is assumed that the large-scale alongshore tidal currents are
small compared to the cross-shore tidal currents, that waves have shore-normal incidence,
that the tidal velocity profile over the inlet is symmetric with respect to the midaxis,
and that the Coriolis force can be ignored. The modeled tidal hydrodynamics are
characterized by an ebb jet during the ebb phase of the tide and a radial inflow pattern
during flood. Two residual eddies are formed. The mechanism behind these current
patterns is explained with vorticity concepts. The modeled bottom patterns are similar to
those of observed symmetric tide-dominated ebb-tidal deltas. In the center of the tidal inlet
an ebb-dominated channel is observed that branches further offshore into two flooddominated
channels. At the end of the ebb-dominated channel a shoal is present. Varying
the tidal prism, the width of the tidal inlet, the wave height, and the bed slope coefficient in
the sediment transport formulation within the range of observed values leaves these
patterns qualitatively unchanged. However, the exact extent and shape of the modeled
deltas are affected by these parameters. Compared to observations, the modeled ebb-tidal
delta is smaller and the ebb-dominated channel is shorter. The observed exponent in the
power law relation between sand volume of the delta and the tidal prism is recovered and
explained with the model.
Original language | Undefined/Unknown |
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Pages (from-to) | F02013/1-F02013/15 |
Number of pages | 15 |
Journal | Journal of geophysical research. Earth surface |
Volume | 111 |
Publication status | Published - 2006 |