Observations and predictions of wave runup, extreme water levels, and medium-term dune erosion during storm conditions

• Published in: Journal of Marine Science and Engineering
• Main Authors: Suanez, Serge, Cancouët, Romain, Floc'H, France, Blaise, Emmanuel, Ardhuin, Fabrice, Filipot, Jean-François, Cariolet, Jean-Marie, Delacourt, Christophe
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), France Energies Marines Brest, Ecole des Ingénieurs de la Ville de Paris (EIVP), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-10-CEPL-0001,COCORISCO,COnnaissance, COmpréhension et gestion des RIsques COtiers(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: dune; storm; extreme water level; erosion; macrotidal beach; runup; NAO; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SDE]Environmental Sciences; Swash; The Toe; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-01176040; https://hal.science/hal-01176040/document; https://hal.science/hal-01176040/file/Suanez_JMSE_2015.pdf; https://doi.org/10.3390/jmse3030674

International audience Monitoring of dune erosion and accretion on the high-energy macrotidal Vougot beach in North Brittany (France) over the past decade (2004-2014) has revealed significant morphological changes. Dune toe erosion/accretion records have been compared with extreme water level measurements, defined as the sum of (i) astronomic tide, (ii) storm surge, and (iii) vertical wave runup. Runup parameterization was conducted using swash limits, beach profiles, and hydrodynamic (Hm0, Tm0,-1, and high tide water level – HTWL) data sets obtained from high frequency field surveys. The aim was to quantify in-situ environmental conditions and dimensional swash parameters for the best calibration of Battjes [1] runup formula. In addition, an empirical equation based on observed tidal water level and offshore wave height was produced to estimate extreme water levels over the whole period of dune morphological change monitoring. A good correlation between this empirical equation (1.01Hmoξo) and field runup measurements (Rmax) was obtained (R2 85%). The goodness of fit given by the RMSE was about 0.29 m. A good relationship was noticed between dune erosion and high water levels when the water levels exceeded the dune foot elevation. In contrast, when extreme water levels were below the height of the toe of the dune sediment budget increased, inducing foredune recovery. These erosion and accretion phases may be related to the North Atlantic Oscillation Index.