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

• Published in: Geomorphology (Amsterdam, Netherlands) Netherlands), 2024-01, Vol.445, p.108972, Article 108972
• Main Authors: Vandenhove, Marine, Castelle, Bruno, Nicolae Lerma, Alexandre, Marieu, Vincent, Dalet, Ema, Hanquiez, Vincent, Mazeiraud, Vincent, Bujan, Stéphane, Mallet, Cyril
• Format: Article
• Language: English
• Subjects: Continental interfaces, environment; Sciences of the Universe
• ISSN: 0169-555X
• DOI: 10.1016/j.geomorph.2023.108972

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