The studies carried out in the context of the development of the Epernay PPRi (map of hazards) were carried out on the scale of 1/10 000th, and mapped on a background IGN scan25 enlarged to 1/10 000th. Since regulatory zoning stems from the intersection of the hazard map and the stake map, the accuracy of this mapping cannot be greater than that of the hazards. Consequently, the scale of use of the regulatory zoning is that of 1/10 000 and exploitation on a smaller cadastral scale (1/5000 or 1/2000) is not recommended. However, municipalities wishing to do so may transpose the regulatory map into their planning documents provided that they comply with operating principles in order to take account of the uncertainty associated with the expansion of the zoning, particularly at the boundary of the area.

Indeed, it is not possible to improve the accuracy of the initial data which presents uncertainty about its contours of the order of 10 metres, which is relatively important on the scale of a plot in an urbanised area.

The transposition of the regulatory map into a cadastral planning document cannot therefore be limited to a mere enlargement, which would result in a false precision of the contours. Therefore, a guide defines the principles that would allow municipalities who wish to do so, a transposition into an urban planning document (PLU, municipal map) taking into account the uncertainties between each area. It must also make it possible to define the area regulation to be applied when considering planning permissions.

The hazard that made it possible to construct the Regulatory Zoning, as well as the stakes are located under gaspar No. 51DDT20170001

Spatial resolution: 1/2 500

Genealogy: The limits of the uncertainty band are not represented on the graphic documents of the RPP, they are not official in nature. The boundaries of the uncertainty band straddle the separation between two zones of the Regulatory Zonage, which do not follow cadastral or administrative boundaries. The width of this limit is set at 10 metres. A guide to the interpretation of this band sets out the principles for its operation.

For natural PPRs, the Environmental Code defines two categories of zones (L562-1): risk-exposed areas and areas that are not directly exposed to risks but where measures can be foreseen to avoid exacerbating the risk.

Depending on the level of hazard and the issues, each area is subject to an enforceable regulation that sets out, in a clear and operational manner, the regulatory measures that apply to each of the restricted areas. The Regulation generally distinguishes five types of zones:

1. “Building prohibited areas”, referred to as “red zone”, depending on the level of hazard in an area with little or no construction, or in an agricultural or natural area, then the general rule is the prohibition on construction;
2. “areas subject to requirements”, referred to as “magenta zone”, “medium blue zone” or “light blue zone”, depending on the level of hazard in an urbanised area, then the projects are subject to requirements adapted to the type of issue;
3. “white areas” not defined in the Regulation and for which the RPIP does not apply, as they are not subject to hazard.

The identification of these homogeneous areas results in the development of a mapping of the regulatory zoning of the PPRi.

The hazard, the stakes, which made it possible to construct this regulatory Zonage, as well as the reference ratings are located under the no. gaspar 51DDT20170001

Spatial resolution: 1/10 000

Genealogy: The boundaries of a restricted area are shown on the graphical documents of the RPP. Regulatory limits are generally set on natural phenomena, which do not follow cadastral or administrative boundaries. A RPP determines the boundaries of the different restricted areas based on the calculated right-of-way of the site’s hazardous events. Some RPPs may sometimes contain regulations associated with linear or point configurations (cavitates, runoff axis, etc.). Linear and point graphic primitives are to be used in these cases respectively.