Crapoulet, A., Héquette, A., Levoy, F. and Bretel, P., 2016. Using LiDAR topographic data for identifying coastal areas of northern France vulnerable to sea-level rise. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1067 - 1071. Coconut Creek (Florida), ISSN 0749-0208.
A major portion of the coast of northern France consists of wide macrotidal beaches and coastal dunes protecting low-lying backshore areas (mostly reclaimed lands) from marine flooding. Although the shoreline was stable or even prograded seaward in places during the last decades, several coastal areas underwent severe erosion during the same period, while flooding sporadically occurred locally during major storms. A study of the potential impacts of sea-level rise on the coast of northern France was conducted based on airborne LiDAR topographic data collected from 2008 to 2014. Mapping of areas at risk of erosion and flooding during storm-induced events associated with high water level with a 100-year return period by 2050 was carried out using high water level statistics derived from tide gauge measurements, offshore wave climate statistics, and a sea-level rise projection based on RCP6.0 scenario (IPCC, 2013). Wave run-up was computed based on the Cariolet and Suanez (2013) equation developed for macrotidal beaches and using beach topographic profiles extracted from the LiDAR data. Results show that marine flooding would still be limited in 2050 even with a higher sea-level, but reveal that coastal dune erosion will most likely be widespread (Fig. 1). However, our study also shows that if coastal retreat proceeds during the next decades at the same or higher rates as today, several coastal dune systems will be entirely eroded in the near future, which would result in extensive storm-induced marine flooding in several coastal areas.