The impact of storm Xynthia in 2010 on coastal flood prevention policy in France

Storm Xynthia occurred on 28 February 2010. It was one of the most destructive climatic events to hit metropolitan France for several decades, causing 47 victims in France, among whom more than half died in the department of Vendée. The occurence of various natural phenomena (atmospheric pressure, strength and orientation of the wind, tidal range) at the same time caused a major coastal flood in several urban areas from Vendée and Charente-Maritime (central Atlantic region of France). The evaluation of the disaster highlighted a number of problems, especially delays in approving the PPR-L (Plan de Prévention des Risques Littoraux) that allowed urbanization in the coastal flood plain that exposed population to major natural risks, such as sea level rise and floods. Since 28th February, 2010, the French government has focused on these issues and tried to define in a more accurate way the criteria used for the flood zonings of the PPR-L. A number of circulars and recommendations have been produced and they all specified rules of protection for properties against the risk of flood and the necessary measures for adapting or building current or future houses (e.g. height of the upper floor, presence of an upper floor refuge) in accordance with the level of risk. The objective of this paper is twofold: we wish to highlight the impact of the disaster Xynthia on the production of PPR-L in the short and medium terms while focusing on the example of the town of La-Faute-sur-Mer. We will also analyze the evolution of the regulations since 28 February 2010, with special attention paid to the proposed criteria to define the hazard.