Sediment Transport and Sea Floor Transformation
by Tidal Waves in Shallow Water

V. N. Zyryanov and A. B. Reshetkov

Institute of Water Problems, Russian Academy of Sciences, Moscow, Russia

Received September 2, 1997; in final form, February 16, 1998

Abstract—Sea floor transformation by tidal waves is studied in a semi-infinite channel using theoretical and
experimental methods within a gradient-viscous model of tidal flow in shallow water with a depth less than the
thickness of the Stokes layer h < h_st = , where A is the vertical turbulence viscosity and T is the period of
a tidal wave. In the case when there is no ice cover, the value of the depth is h_st 12 m for a semidiurnal wave;
in ice-covered water, the value of h_st is twice as great. Two cases are considered: (a) a channel with a sand floor
without deficit zones during erosion and (b) a channel with a localized sand ridge over a noneroding floor. It is
shown that the asymmetry of a tidal wave in shallow water causes the generation of suspension residual flow in
the onshore direction. As a result, residual sedimentation with decreasing intensity occurs in the entire region
of erosive velocities in the nondeficit case. Its intensity decreases with the decay of the tidal wave amplitude in
the onshore direction. Localized sand ridges obtain the form of antidunes under the influence of tidal waves
with steep slopes in the offshore direction and flat slopes in the onshore direction. The results of laboratory
experiments confirm the formation of antidunes in the tidal flow.

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