Sedimentary Coastal Cliffs of Normandy: Modalities and Quantification of Retreat
Journal of Coastal Research SI 88 46–60 Coconut Creek, Florida 2019 Sedimentary Coastal Cliffs of Normandy: Modalities and Quantification of Retreat Stéphane Costa†*, Olivier Maquaire†, Pauline Letortu‡, Guillaume Thirard†, Vincent Compain†, Thomas Roulland†, Mohand Medjkane†, Robert Davidson†, Kevin Graff†, Candide Lissak†, Christophe Delacourt∞, Timothée Duguet§, Cyril Fauchard#, and Raphael Antoine# †Caen Normandie University, Unicaen ‡University of Bretagne Occidentale ∞University of Bretagne Occidentale www.cerf-jcr.org UMR CNRS LETG UMR CNRS LETG, IUEM UMR CNRS LGO, IUEM Caen, France Plouzané, France Plouzané, France § # Le Havre Normandie University CEREMA Normandie-Centre UMR CNRS LOMC Rouen, France Le Havre, France ABSTRACT Costa, S.; Maquaire, O.; Letortu, P.; Thirard, G.; Compain, V.; Roulland, T.; Medjkane, M.; Davidson, R.; Graff, K.; Lissak, C.; Delacourt, C.; Duguet, T.; Fauchard, C., and Antoine, R., 2019. Sedimentary coastal cliffs of Normandy: Modalities and quantification of retreat. In: Castelle, B. and Chaumillon, E. (eds.), Coastal Evolution under Climate Change along the Tropical Overseas and Temperate Metropolitan France. Journal of Coastal Research, Special Issue No. 88, pp. 46–60. Coconut Creek (Florida), ISSN 0749-0208. www.JCRonline.org This paper examines the spatial and temporal variations of cliff retreat rates over multi-temporal data of the Normandy cliffs. Data are derived from historical maps and aerial photographs and from recent lasergrammetry and photogrammetry monitoring. The diachronic analysis of all these data gives retreat rates of -0.1 to -0.5 m/yr. in line with the international literature. The spatial variations of the cliff retreat rates, at the Normandy scale, can be explained by geological structure, especially at the cliff foot, but also by the influence of cliff collapses or anthropogenic obstacles that disrupt the longshore drift.
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