Publication Date:
2022-05-26
Description:
Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 1841–1861, doi:10.1175/JPO-D-12-0231.1.
Description:
In this idealized numerical modeling study, the composition of residual sediment fluxes in energetic (e.g., weakly or periodically stratified) tidal estuaries is investigated by means of one-dimensional water column models, with some focus on the sediment availability. Scaling of the underlying dynamic equations shows dependence of the results on the Simpson number (relative strength of horizontal density gradient) and the Rouse number (relative settling velocity) as well as impacts of the Unsteadiness number (relative tidal frequency). Here, the parameter space given by the Simpson and Rouse numbers is mainly investigated. A simple analytical model based on the assumption of stationarity shows that for small Simpson and Rouse numbers sediment flux is down estuary and vice versa for large Simpson and Rouse numbers. A fully dynamic water column model coupled to a second-moment turbulence closure model allows to decompose the sediment flux profiles into contributions from the transport flux (product of subtidal velocity and sediment concentration profiles) and the fluctuation flux profiles (tidal covariance between current velocity and sediment concentration). Three different types of bottom sediment pools are distinguished to vary the sediment availability, by defining a time scale for complete sediment erosion. For short erosion times scales, the transport sediment flux may dominate, but for larger erosion time scales the fluctuation sediment flux largely dominates the tidal sediment flux. When quarter-diurnal components are added to the tidal forcing, up-estuary sediment fluxes are strongly increased for stronger and shorter flood tides and vice versa. The theoretical results are compared to field observations in a tidally energetic inlet.
Description:
Project funding
was provided by the German Research Foundation
(DFG) in the framework of the Project ECOWS (Role
of Estuarine Circulation for Transport of Suspended
Particulate Matter in the Wadden Sea, BU 1199/11) and
by the German Federal Ministry of Research and Education
in the framework of the Project PACE [The
future of the Wadden Sea sediment fluxes: still keeping
pace with sea level rise? (FKZ 03F0634A)].
Description:
2014-03-01
Keywords:
Channel flows
;
Coastal flows
;
Mixing
;
Transport
;
Turbulence
;
Single column models
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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