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Impacts des tempêtes sur la morphodynamique du profil côtier en milieu macrotidal

Aurélie Maspataud 1
1 Equipe 4 - Morphodynamique des littoraux
LOG - Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187
Abstract : Along the southern coast of the North Sea, the coastline east of Dunkirk consists of wide barred sandy beaches and coastal dunes that protect low lying and densely populated reclaimed land, which are highly vulnerable to marine flooding with projected sea level rise associated with global change. The objectives of this study and the adopted methodological approach are based on several spatial and temporal scales, in order to assess the effects of storms on the morphodynamic evolution of a low-lying, macrotidal and fetch limited, unconsolidated coast. At event scale, our measurements revealed very different morphological responses of the coast to energetic and stormy conditions at two study areas located 4 km away. This contrasting response results from different hydrodynamic conditions at each site, with erosion prevailing along the western part of the study area while stability or even accumulation characterized the eastern sector. On a seasonal to multi-year scale, our results showed that the coastal profile tends to recover during post-storm conditions underlining the role of aeolian sand transport in dune-foot recovery and foredune sand supply. At medium term, from 1957 to 2010, the evolution of the east Dunkirk shoreline shows a large spatial and temporal variability, which seems to be explained by differences in wave energy at the coast, partly linked with variation in nearshore bathymetry, but also with changes in meteorological and oceanographic forcings and, locally, with anthropic interventions. Some erosive conditions were identified, such as persistent onshore (from N-NW) winds blowing at a speed of more than 8 m/s during more than 48 hours, for example. Data collected in this study were also used for modelling the short-term response of the coast to storm events with two morphodynamic models: SBEACH and X-BEACH. Although both models gave consistent results, they appear to be complementary as one was more efficient to simulate the morphodynamic evolution of the coastal profile while the other was better in modelling hydrodynamics across the profile.
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Contributor : Aurélie Maspataud <>
Submitted on : Wednesday, January 11, 2012 - 4:07:13 PM
Last modification on : Wednesday, October 14, 2020 - 3:56:24 AM

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Aurélie Maspataud. Impacts des tempêtes sur la morphodynamique du profil côtier en milieu macrotidal. Océanographie. Université du Littoral Côte d'Opale, 2011. Français. ⟨tel-00658671⟩

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