Effects of nearshore sand bank and associated channel on beach hydrodynamics: implications for beach and shoreline evolution
Hequette, A.; Ruz, M.-H.; Maspataud, A.; Sipka, V. (2009). Effects of nearshore sand bank and associated channel on beach hydrodynamics: implications for beach and shoreline evolution. J. Coast. Res. SI 56: 59-63
In: Journal of Coastal Research. Coastal Education and Research Foundation: Fort Lauderdale. ISSN 0749-0208; e-ISSN 1551-5036, more
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Document type: Conference paper
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| Keywords |
Physics > Mechanics > Fluid mechanics > Hydrodynamics
Sedimentary structures > Bed forms > Banks (topography) > Sand banks
Shoreline changes
Tidal environment
Topographic features > Landforms > Coastal landforms > Beaches
ANE, North Sea [Marine Regions]
Marine/Coastal |
| Author keywords |
Tidal sand bank; macrotidal coast; North Sea |
| Authors | | Top |
- Hequette, A.
- Ruz, M.-H., more
- Maspataud, A.
- Sipka, V.
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| Abstract |
Tidal banks are common in the southern North Sea where they form linear shore-parallel or slightly oblique sand bodies. A 13 day field experiment was conducted in February 2007 on a macrotidal barred sandy beach of northern France, on the southwestern shore of the North Sea, in order to assess the effects of a shallow nearshore sand bank on beach/nearshore hydrodynamics. Two Acoustic Doppler Current Profilers (ADCP) were moored ill the surf zone and two electromagnetic current meters were deployed on the middle beach. The instruments were deployed along two shore-perpendicular transects, the first being located onshore of a sand bank extending along an area characterized by shoreline retreat, while the other was positioned in a prograding area of the coastline, about 2 kill eastward of the bank edge. Results obtained in the intertidal zone during moderate wind events, showed that significant wave height was similar or even slightly higher behind the bank compared to the other experimental site, indicating that the bank did not significantly enhance wave energy dissipation. Strong flood tidal currents, up to 0.7 m/s, were recorded at both sites during the experiment, but Current speed was generally higher behind the bank, presumably because tidal flows are constrained in the channel located between the sand bank and the beach. These results suggest that sand banks do not necessarily protect the coast from the action of incoming waves and may locally favor downcurrent sediment deposition at the coast due to increased sediment transport in nearshore channel. |
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