Beach-dune Recovery from the Extreme 2013-2014 Storms Erosion at Truc Vert Beach, Southwest France: New Insights from Ground-penetrating Radar

Robin, N.; Billy, J.; Castelle, B.; Hesp, P.; Laporte-Fauret, Q.; Nicolae-Lerma, A.; Marieu, V.; Rosebery, D.; Bujan, S.; Destribats, B., and Michalet., 2020. Beach-dune recovery from the extreme 2013-2014 storms erosion at Truc Vert Beach, Southwest France: New insights from ground-penetrating radar. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 588–592. Coconut Creek (Florida), ISSN 0749-0208. Foredunes are efficient natural coastal defenses acting as protective barriers during storm events. A striking example is the response of coastal dunes along the Aquitaine Coast (SW France) to the 2013-2014 winter, which was the most energetic winter since at least the mid-20th century in most of the NE Atlantic. The aim of this study is to analyze the (partial) foredune recovery from the 2013-2014 winter at Truc Vert beach using ground-penetrating radar (GPR) and through the coastal dune internal structure. Geophysical data was compared with semi-monthly DGPS topographic data of the beach, UAV-photogrammetry and Airborne LiDAR surveys of the coastal dune. Three main recovery phases were identified from the 2013-2014 winter: (i) aggradation of the upper-beach and dune front-crest during the post-storm summer; (ii) distinct phases of incipient dune-foot development with dune-crest stability during the following year, and (iii) since 2016, aggradation of both dune-foot and dune front-crest tending towards an equilibrium profile. This study shows that GPR surveys, combined with chronological topographic data, is an efficient tool to provide comprehensive understanding of the beach-dune system evolution at a decadal scale. This approach opens new perspectives to document foredune recovery timing and magnitude along sandy coasts.