Currents in a small tidal-flat channel
Citable URI
https://hdl.handle.net/1912/4408As published
https://doi.org/10.1016/j.csr.2010.10.007Keyword
Tidal flat; Flow in channels; Drag coefficientAbstract
Near-bottom currents observed on a tidal flat are compared with those observed 50 m away
inside a shallow (0.25 to 0.40 m deep) channel. For water depths between 0.5 and 2.5 m
(when both current meters are submerged), current speeds 0.13 m above the bed on the flat
are about 30% greater than those observed 0.13 m above the bed in the channel, and are
approximately equal to those observed 0.58 m above the channel bed (0.26 m above the flat
elevation). Flow directions on the flat are similar to those in the channel. For flows parallel to
the channel axis, the ratio of speeds 0.13 m above the bed on the flat to those 0.13 m above
the bed in the channel decreases from about 1.4 to about 1.1 with increasing water depth,
consistent with conservation of mass. For flows directed across the channel axis, the ratio of
speeds increases from about 1.3 to about 2.2 with increasing water depth. The corresponding
ratio of the vertical velocity variances (a proxy for turbulence) decreases from about 1.5 to
about 0.2, suggesting that the turbulence near the bed of the channel is greater than that near
the bed of the flat for water depths greater than about 1.0 m. In contrast, for along-channel
flows, the channel and flat turbulence levels are similar. Drag coefficients estimated with the
vertical velocity variance or with a cross-shore momentum balance are approximately 70%
larger in the channel than over the visually smoother flat.
Description
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 31 (2011): 9-14, doi:10.1016/j.csr.2010.10.007.
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Suggested Citation
Preprint: Elgar, Steve, Raubenheimer, Britt, "Currents in a small tidal-flat channel", 2010-06, https://doi.org/10.1016/j.csr.2010.10.007, https://hdl.handle.net/1912/4408Related items
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