Dataset Direct Download Service (WFS): Confounding and swelling of clays in the Nièvre (58)

The mapping of the clay removal hazard on the Nièvre department is extracted from the national mapping from the BRGM in force since 1 January 2020. This mapping is a zoning of the probability of occurrence of the phenomenon of shrink-inflating of clay soils. A susceptibility map was first drawn up on the basis of purely physical criteria by the BRGM from the geological maps of the department, which were interpreted taking into account the following factors for each geological formation: — the proportion of clay material within the formation (lithic analysis); — the proportion of blowing minerals in the clay phase (mineralogical composition); — the geotechnical behavior of the material. For each of the clay formations identified, the hazard level is ultimately the result of the level of susceptibility thus obtained with the density of sinister swelling, reported to 100 km² of actual urbanised outcropping surface. The boundaries of a hazard zone are shown on the hazard map depending on the level of the hazard. In other words, the polygon objects representing the hazard areas form a partial coverage of the study area, each of which is a closed polygon in which hazards have the same low to high intensity level. Therefore, the criterion for the separation of hazard zones is the level of hazard. * The DDT is not responsible for publishing this data, this metadata sheet is for information purposes only