Map visualisation service (WMS) of the dataset: Hazard removal-swelling of clays Research form for the Department of the North

Removal by drying out of clay soils during a severe and/or lasting drought produces deformations of the soil surface (differential bones). It may be followed by swelling phenomena as initial hydrogeological conditions are restored or more rarely creep phenomena with softening. Nature of the phenomenon: In temperate climate, clays are often close to their saturation state, so their swelling potential is relatively limited. On the other hand, they are often far from their withdrawal limit, which explains why the most important movements are observed in dry periods. The most superficial slice of soil, 1 to 2 m deep, is then subjected to evaporation. The result is a removal of the clays, which manifests itself vertically by settling and horizontally by the opening of cracks, classically observed in the bottoms of drier pools.