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dc.contributor.authorRalston, David K.  Concept link
dc.contributor.authorGeyer, W. Rockwell  Concept link
dc.contributor.authorTraykovski, Peter A.  Concept link
dc.contributor.authorNidzieko, Nicholas J.  Concept link
dc.date.accessioned2013-08-21T19:02:13Z
dc.date.available2013-08-21T19:02:13Z
dc.date.issued2012-01-25
dc.identifier.urihttps://hdl.handle.net/1912/6178
dc.descriptionAuthor Posting. © The Author(s), 2012. 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 60, Suppl. (2013): S40–S57, doi:10.1016/j.csr.2012.02.004.en_US
dc.description.abstractTidal flats at a river mouth feature estuarine and fluvial processes that distinguish them from tidal flats without river discharge. We combine field observations and a numerical model to investigate hydrodynamics and sediment transport on deltaic tidal flats at the mouth of the Skagit River, in Puget Sound, WA during the spring freshet. River discharge over tidal flats supplies a mean volume flux, freshwater buoyancy, and suspended sediment. Despite the shallow water depths, strong horizontal density fronts and stratification develop, resulting in a baroclinic pressure gradient and tidal variability in stratification that favor flood-directed bottom stresses. In addition to these estuarine processes, the river discharge during periods of low tide drains through a network of distributary channels on the exposed tidal flats, with strongly ebb-directed stresses. The net sediment transport depends on the balance between estuarine and fluvial processes, and is modulated on a spring-neap time scale by the tides of Puget Sound. We find that the baroclinic pressure gradient and periodic stratification enhance trapping of sediment delivered by the river on the tidal flats, particularly during neap tides, and that sediment trapping also depends on settling and scour lags, particularly for finer particles. The primary means of moving sediment off of the tidal flats are the high velocities and stresses in the distributary channels during late stages of ebbs and around low tides, with sediment export predominantly occurring during spring low tides that expose a greater portion of the flats. The 3-d finite volume numerical model was evaluated against observations and had good skill overall, particularly for velocity and salinity. The model performed poorly at simulating the shallow flows around low tides as the flats drained and river discharge was confined to distributary channels, due in part to limitations in grid resolution, seabed sediment and bathymetric data, and the wetting-and-drying scheme. Consequently, the model predicted greater sediment retention on the flats than was observed.en_US
dc.description.sponsorshipThis work was supported by the Office of Naval Research.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.relation.urihttps://doi.org/10.1016/j.csr.2012.02.004
dc.subjectTidal flatsen_US
dc.subjectSediment transporten_US
dc.subjectSediment trappingen_US
dc.subjectDistributary channelsen_US
dc.subjectStratificationen_US
dc.subjectSalinity frontsen_US
dc.subjectTidal asymmetryen_US
dc.subjectVelocity skewnessen_US
dc.subjectNumerical modelen_US
dc.titleEffects of estuarine and fluvial processes on sediment transport over deltaic tidal flatsen_US
dc.typePreprinten_US


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