Map Viewing Service (WMS) of the dataset: PPRI of Lay Aval — Reference Ratings of the Plan for the Prevention of Predictable Natural Risks Flood — Vendée

The reference rating corresponds to the rating of the water body modelled to the right of an existing project or construction plus a safety factor, called “hydraulic revanche” and a value of 20 cm. Thus “out of water” of a construction will result in a first floor rating greater than or equal to that reference rating as indicated on the regulatory zoning mapping. It is displayed in NGF-IGN 69 meter, i.e. in meter in the official leveling network in metropolitan France, which is attached to the Marseilles tidegrapher. These odds are reported perpendicular to the river axis at regular intervals on the regulatory zoning map. At a given location, the reference rating is the value immediately upstream or at the right of the place in question. Between two reference ratings, the applicable rating will be calculated by linear interpolation between the two known ratings shown on the plane.