Recherche d’indicateurs géomorphologiques de variation de l’orientation des houles sur les côtes françaises de l’Atlantique et de la Manche au cours des 25 dernières années, analyse des données et comparaison avec les données de l’atlas numérique de houle EDF-LNHE

Identification of geomorphological indicators of incident waves direction along the Channel and the Atlantic French coasts during the last 25 years, data analysis and comparison with data of the EDF-LNHE numerical atlas of waves

LETG Géomer UMR 6554 CNRS Institut Universitaire Européen de la Mer, place Nicolas Copernic, 29 280 Plouzané

Auteur de correspondance : alain.henaff@univ-brest.fr

Résumé

Long-term evolutions of wave orientation are important parameters that explain shoreline evolutions and coastal risks. Within the DISCOBOLE project (Données pour le dImensionnement des Structures Côtières et des Ouvrages de BOrd de mer à Longue Echéance), the lack of record of this parameter along the Channel and Atlantic French coasts requires to identify geomorphological features (geomorphological indicators) that indicate wave orientations and evolutions during the last decades. Within this aim, the evolutions of the axis of trailing spits, tombolos and cuspate beaches and beach rotations are analysed over the last decades by mean of present and old aerial photographs and maps. Alterning periods of meridian and zonal orientations are then identify. From 1979 to 2003, results are compared to the data obtained in the EDF-LNHE numerical atlas of waves.