摘要：When is led a prevention initiative concerning flood risk, the recall of old events allows just as much to act as pedagogy to legitimize the initiative. So as it is written in the information leaflet on the “Plan de Prévention des Risques d’Inondation” (PPRI):«Alsace did not know any more exceptional floods since 1910. In almost a century, the flood risk thus naturally faded of our memory”. A paradoxical assertion because the floods of 1910 are not taken into account for risk mapping. Only the recent floods (1983, 1990) are used as benchmarks. We were able to show [1] that, although legitimate as reference events, the floods of 1910 and many others had become manifestly underestimated for multiple reasons connected to the history of Alsace, or due to disorganization of the archives. Worse, these riks unawareness is shared by all the actors, causing problems of acceptance of the risk and their management, and an additional vulnerability in terms of population behavior before, during and after the crises. This is the reason why an online participative database (ORRION) has been created. the objective of this database is to inform and to share the information about floods history, in the particular context of a cross-border territory (France, Germany, Switzerland). This tool has been immediately involved into risks prevention actions (PAPI, PPRI).
