The 14.5-km North-Médoc coast, southwest France, is a high-energy mesoto macro-tidal environment adjacent to the largest estuary in Europe. Over the last centuries, this coastline has locally suffered periods of severe erosion, threatening coastal infrastructures and requiring the progressive implementation of coastal structures and, more recently, localized beach nourishments. This contribution combines 84 years (1937-2021) of shoreline data from various sources, 118 years (1903-2021) of shallow water bathymetric surveys and historical photographs. Results show that, averaged in both time and space, the coast eroded by-0.6 m/yr over the last 84 years, but with a large alongshore and temporal variability. Erosion is locally peaking at-5.2 m/yr, while accretion is restricted to a remote 2.5-km and locally peaks at 5.4 m/yr. A salient characteristic of shoreline evolution is the alternation of rapid erosion ( 20 m/yr) periods over relatively short intervals (≈ 10 years) and across limited alongshore distances (e.g. couple of< Réduire

Mots clés en anglais

Coastal erosion

Estuary mouth

Shoal welding

Bathymetric control

Multidecadal variability

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https://oskar-bordeaux.fr/handle/20.500.12278/187806

DOI

http://dx.doi.org/10.1016/j.geomorph.2023.108972

Project ANR

Comprendre et prévoir l'évolution contemporaine du traite de côte dans un contexte de changement climatique par assimilation de données satellite dans les modèles hybrides - ANR-21-CE01-0015

Unités de recherche

EPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805

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Secular shoreline response to large-scale estuarine shoal migration and welding

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