Preliminary Flood Risk Assessment for the European Directive: inventory of French past floods
Evaluation préliminaire du risque d'inondation dans le cadre de la Directive Inondation : recensement en France des crues remarquables
Résumé
An inventory of about 2000 French flood events has been achieved in 2011, in the framework of the Preliminary Flood Risk Assessment of the European Flood Directive. In collaboration with local authorities, a set of about 300 significant past floods has been documented with a short presentation (1 to 2 pages) of the hydro-meteorological conditions and the adverse consequences. The paper presents the methodological framework for data collection, based on a 6 month survey of the documentary sources located in the regional water authorities. The selection of the 300 past floods was based on several criteria: intensity and/or spatial extent of the flood, important damages, specific type of flood, recent flood still active in memory. All sources of flooding have been addressed: fluvial, pluvial, groundwater, sea water, artificial water bearing infrastructure, glacial lake outburst flood. As an illustration we present here eight extreme events from the XX-XIXth centuries which had in France important consequences : oceanic floods on winter 2000-2001 (Brittany), mixed rainfall and snowmelt floods on January 1910 (Seine basin); several flash Mediterranean floods on March 1930 (Tarn and Garonne rivers), October 1940 (Tech, Tet and Agly rivers) and November 1999 (Aude basin); the dam breaking flood on December 1959 (Malpasset dam); the Hyacinthe cyclone at La Reunion in January 1980 (world record of precipitation between 5 to 15 days); the Xynthia windstorm event on February 2010 (Atlantic coast). Some perspectives are addressed to improve the knowledge of past floods.
Un recensement de près de 2000 inondations a été réalisé en 2011 sur l’ensemble du territoire français dans le cadre de l’Evaluation Préliminaire des Risques d’Inondation (EPRI), première phase de la Directive européenne sur les Inondations. En collaboration étroite avec les services de l’Etat concernés, un choix d’environ 300 événements remarquables a ensuite été établi, pour lesquels une description courte (1 à 2 pages) a passé en revue la genèse de l’inondation et ses conséquences. L’article décrit le mode opératoire suivi pour la collecte des données et la sélection des événements puis présente à titre d’illustration huit inondations remarquables (1910, 1930, 1940, 1959, 1980, 1999, 2000-01 et 2010). Il se termine par les perspectives de valorisation de cette enquête 2011.