Coastal flood protection systems. Xynthia feedback experience. Case studies conclusion

Résumé

The determination of the borders and the internal structure of a coastal flood protection system, then the understanding of its behavior during past events contribute widely to determine actions to improve its performance. To set up in this domain a proven methodology, transposable in other places prone to episodes of marine floods, four sites with contrasted configurations were chosen for case studies. These sites are representative of most of the situations met during the storm Xynthia which hit the French Atlantic coast in February, 2010:

- Loix is a peninsula surrounded by a set of basins and marshes,

- Les Boucholeurs extends in border of a vast bay and presents houses on the sea front directly exposed to waves as well as setback constructions on the location of former leveed marshes,

- Boyardville-La Perrotine is an urbanized zone crossed by a leveed canal connecting the sea front with a vast zone of swamp and a marina,

- Batz-sur-Mer is characterized by salterns along which urbanization developed.

These sites are structured by a network of natural features, levees, canals and ditches, road and railway infrastructures, involving many actors for their management.

This paper presents case studies conclusions. It focuses on the way the main identifiable stakes were actually protected during the passage of the storm Xynthia.