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| Titel |
Turning the tide: mutually evasive ebb- and flood-dominant channels and bars in an experimental estuary |
| VerfasserIn |
M. G. Kleinhans, T. M. Rosmalen, C. Roosendaal, M. Vegt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: Proceedings of river, coastal and estuarine morphodynamics ; Nr. 39 (2014-04-01), S.21-26 |
| Datensatznummer |
250121300
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| Publikation (Nr.) |
 copernicus.org/adgeo-39-21-2014.pdf |
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| Zusammenfassung |
| Tidal bars in estuaries are poorly understood compared to fluvial bars. There
is limited theory that predicts tidal bar dimensions. Moreover, where fluvial
channels bifurcate around bars, tidal channels around bars often develop
either flood- or ebb-dominance which remains unexplained. Tidal experiments
are rare and have not reproduced these phenomena to date because these are
usually highly ebb-dominated. Here we report preliminary experiments in a
novel setup that produce tidal bars from an initial situation with flat bed
and exactly symmetrical ebb- and flood-related sediment mobility. The bars
initially develop in a saw-tooth pattern with mutually evasive ebb- and flood
channels. The tips of the bars evolve further into lobate bars built up from
sediment from excavating channels. The bar tips form steep and high
obstructions for the opposing flow direction, which then diverges into
evasive channels. The bars develop into a diamond shape as channels bifurcate
and deepen around it. We further found that bar height correlates well to bar
width but not with bar length, whilst bar length correlates well to the tidal
excursion length. As the experiment progressed scour holes developed that
affected the channel and bar pattern and are considered artifacts of the
experiment. We conclude that the mutually evasive ebb- and flood-dominance of
channels emerges simultaneously with the onset of tidal bar formation, and
that these preliminary data confirm results from linear stability analyses.
The results are proof of principle for the novel experimental setup for tidal
systems. |
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