Envelopes near Potential Floods of Auvergne-Rhône-Alpes rivers

As part of the Preliminary Flood Risk Assessment (EPRI), DREAL Rhône-Alpes in conjunction with the DREAL Bourgogne, Franche-Comté, Languedoc-Roussillon and PACA have carried out near flood envelopes (EAIP) throughout the Rhône-Méditerranée basin, taking into account 2 phenomena: river overflow flooding (EAIPce) flooding by Marine Submersions (EAIPsm) These envelopes have been developed with a view to approaching the contours of extreme events. In this sense, the effect of hydraulic structures (bars and protective dams) is not considered. Except in particular cases, protection dams are considered transparent. EAIP “this” represents the potential hold of overflows of all streams, including small and intermittent streams, torrents, talweg bottoms. Since the dikes are not taken into account, the resulting right-of-way may be considered, in the first approximation, to incorporate the effect of the failure of the protective structures. However, it does not integrate runoff by pouring (sludge flows and runoff located outside the talwegs) or the specific phenomena associated with local saturation of urban sanitation systems. EAIPs are intended to be the subject of a more precise analysis of phenomena during the following stages of the Flood Directive for the territories concerned by an IRR or a local strategy. The method used to construct EAIPs led to merging information sources variable scale and precision. It generates uncertainties that may be occasionally significant (overestimate of right-of-way or, on the contrary, underestimate). EAIPs are therefore not a mapping of flood zones and should not be confused with: plans to prevent the foreseeable natural risks of floods or coastlines; atlases of flood or submersible areas; mapping of Submersible Areas and Flood Risks of the Territories with Significant Flood Risks (TRI). EAIPs cannot be used to identify flood zones in administrative or regulatory procedures. Moreover, given the scales of the data mobilised, their graphic exploitation makes sense only for scales greater than 1/100 000e.