UAV monitoring of 3-year Foredune Partial Recovery from a Severe Winter: Truc Vert Beach, SW France

Abstract

Guillot, B., Castelle, B., Marieu, V., Bujan, S., and Rosebery, D., 2018. UAV Monitoring of 3-year foredune partial recovery from a severe winter: Truc Vert beach, SW France. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 276–280. Coconut Creek (Florida), ISSN 0749-0208.The recent development of ultra-light civil UAVs and photogrammetric techniques provides new and efficient means to remotely sense the coastal topography at high spatial and temporal resolutions along spatially extensive areas. Truc Vert, SW France, is a high-energy meso-macrotidal beach backed by a preserved high and wide coastal dune system. This coastal dune system, which had been relatively stable over the last 70 years, was severely eroded during the winter of 2013/2014 with 800-m long and up to 8-m high cuspate erosion scarps. Since then, the foredune has been slowly recovering. This 3-year period was characterized, at the early stage, by the destabilisation of the scarped dune by trough blowouts, scarp slumping and filling and seasonal beach berm dynamics. The onset of foredune recovery occurred subsequently, and was characterized by the development of a dune ramp. This ramp provided efficient conduit for beach-dune delivery/exchange of sediment by the end of the study despite the high-energy winter of 2015/2016 drove localized dune erosion. The coastal dune did not fully recover with an approximately 60% average recovery within 3 years, an overall accretion due primarily to incipient foredune formation and foredune growth in height. The timing and magnitude of the incomplete recovery sequence from the UAV surveys provide an outstanding measure of coastal dune resilience to severe storms in this region of the world.