Residual currents in the Severn Estuary and their effects on dispersion
Uncles, R.J. (1982). Residual currents in the Severn Estuary and their effects on dispersion. Oceanol. Acta 5(4): 403-410
In: Oceanologica Acta. Elsevier/Gauthier-Villars: Montreuil. ISSN 0399-1784; e-ISSN 1878-4143, more
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| Keywords |
Models > Mathematical models
Motion > Water motion > Circulation > Water circulation > Shelf dynamics > Estuarine dynamics
Motion > Water motion > Water currents
Transport processes > Diffusion
Marine/Coastal; Brackish water |
| Abstract |
Depth averaged residual currents and associated water levels resulting from M2 tidal oscillations in a numerical model of the Severn Estuary, UK, are presented. Current patterns are dominated by eddies. Residual currents produce enhanced transverse and axial dispersion by the mechanism of tidal "random walk". The axial dispersion coefficient due to residual current eddies is shown to be comparable to the observed long-term value for the seaward section of estuary considered, and is much greater than values which can be attributed to vertical shear in tidal and residual currents, or transverse shear in tidal currents. Transverse mixing due to tidal "random walk" is found to be much greater than that which can be attributed to other known mechanisms. Estuarine width is shown to be important in that it limits the size of horizontal eddies, and therefore controls the dispersion for given tidal and residual current speeds. |
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