Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

Schramkowski, G.P.; De Swart, H.E.; Schuttelaars, H.M.

doi:doi:10.1007/s10236-009-0235-0

Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

Title

Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

Author

Schramkowski, G.P.
De Swart, H.E.
Schuttelaars, H.M.

Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Delft Institute of Applied Mathematics

Date

2009-10-29

Abstract

A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom profile. For a deep, well-mixed, tidally dominated channel, partial slip decreases the relative importance of Coriolis deflection on the generation of cross-channel flow patterns. This has profound implications for the lateral distribution of residual salinity that drives the cross-channel residual circulation pattern. Transverse sediment transport, however, is always found to be governed by a balance between advection of residual sediment concentration by residual lateral flow on the one hand and cross-channel diffusion on the other hand. Hence, the changes in the cross-channel distribution of residual salinity modify the lateral sediment distribution. For no slip, a single turbidity maximum occurs. In contrast, partial slip gives a gradual transition to a symmetrical density distribution with a turbidity maximum near each bank. For a more shallow, partially mixed tidal channel that represents the James River, a single turbidity maximum at the left bank is found irrespective of the near-bed slip condition. In this case, semi-diurnal contributions to sediment distribution and lateral flow play an important role in cross-channel sediment transport. As vertical viscosity and diffusivity are increased, a second maximum at the right bank again exists for partial slip.

Subject

turbidity
estuary
sediment transport
morphodynamic equilibrium

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http://resolver.tudelft.nl/uuid:76b7747c-5b46-49a3-8cb1-1881f388718a

DOI

https://doi.org/10.1007/s10236-009-0235-0

Publisher

Springer

ISSN

1616-7341

Source

Ocean Dynamics, 60 (2), 2010