Relationship between current measurements and sonographs of subtidal bedforms in the macrotidal Tay Estuary, Scotland
Duck, R.W.; Wewetzer, S.F.K. (2000). Relationship between current measurements and sonographs of subtidal bedforms in the macrotidal Tay Estuary, Scotland, in: Pye, K. et al. Coastal and estuarine environments: sedimentology, geomorphology and geoarchaeology. Geological Society Special Publication, 175: pp. 31-41. https://dx.doi.org/10.1144/GSL.SP.2000.175.01.04 In: Pye, K.; Allen, J.R.L. (Ed.) (2000). Coastal and estuarine environments: Sedimentology, geomorphology and geoarchaeology. Geological Society Special Publication, 175. The Geological Society: London. ISBN 1-86239-070-3; e-ISBN 9781862394230. 435 pp. https://dx.doi.org/10.1144/GSL.SP.2000.175, more In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719; e-ISSN 2041-4927, more |
| Keywords | Marine/Coastal; Brackish water |
| Authors | | Top | - Duck, R.W.
- Wewetzer, S.F.K.
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| Abstract | Near bottom current measurements have been compared with sonographs revealing a variety of subtidal dune geometries at eight stations in the middle reaches of the macrotidal Tay Estuary, Scotland. At six stations, dune asymmetries did not support the tidal dominance expressed in terms of maximum or average current speeds. Determination of bottom tidal current dominance according to the length of time during which a speed of 0.5 ms-1 was exceeded, as a proxy for the inequality of the total ebb and flood tide bedload sediment transports, provides a better, but not perfect, correlation with sonographs. Other controls on dune asymmetry and reversal are height, sediment discharge rate and bottom current velocity fluctuations. The study has shown that bedload transport processes and pathways in this relatively small (c. 8 km²), dynamic part of the estuary are far more complex than previously inferred and near bed flows do not simply correspond with the surface water circulation pattern. Neither sonographs nor current data alone are adequate to gain an understanding of subtidal bedforms in such an environment. |
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