DROUGHT

Understanding the phenomenon of clay shrinking and swelling by means of an indicator aggregated by commune: the magnitude of droughts

This article presents the general methodology implemented in this doctoral thesis in partnership with Météo-France, CCR and BRGM and which concerns the development of a model to assess the loss experience related to the phenomenon of clay shrinking and swelling.

Sophie Barthelemy, Bertrand Bonan, Gilles Grandjean, David Moncoulon and Jean-Christophe Calvet

Tree detection from very high-resolution imagery data in drought-prone areas

The root system of one or more trees located in the direct vicinity of the foundations of a house can contribute to the aggravation of the Clay Shrinking and Swelling (CSW) phenomena on the building structure. With a view to integrating this information into the internal CSS drought hazard model, a tree detection study at sub-parcel level was carried out on the Île-de-France commune: Montigny-le-Bretonneux. Very High Resolution (VHR at 20cm) imagery data, remote sensing and Artificial Intelligence methods were used to accurately map tree cover, estimate tree heights, and identify the most exposed dwellings. The results obtained and the computing times required at commune level made it possible to assess the applicability of the approach to the entire mainland territory.

Thomas Onfroy, Aurélien Couloumy, Antoine Labonne, Michel Médic and Jean-Baptiste Henry