History 2011 — Large-scale land use by remote sensing 2011: Department of Drôme

Attention: only the floor cover is processed in this delivery. The data recipe has not been carried out, this lot is still to be considered as a test batch to be improved. CEREMA worked in 2013 as part of an exploratory study for the DREAL Rhônes Alpes, the DRAAF Rhône-Alpes and the Regional Council of Auvergne-Rhône-Alpes (Région Auvergne-Rhône-Alpes) on the semi-automatic implementation of a top-level land use layer on 3 test territories based on satellite images. The objective of the method is to help the departments in charge of planning territories to calculate the quantified indicators characterising land use and its evolution in order to meet the regulatory requirements in this area. The method of constructing the layer consists of combining automatic extraction of information from satellite images (supervised classifications) and post-processed information from existing databases (BD Topo, RPG...). If the construction process differs from the IGN process for setting up the future OCS Grande Scale layer, and if the layer specifications are less ambitious, the objective is to have a layer consistent with the national benchmark: compatible nomenclature, use of the same structural skeleton of the territory, same minimum collection unit etc. The interest of such data lies in the following points: — temporal homogeneity of the source information (the satellite images used — RapidEye images at 5 m of GEOSUD resolutions) are acquired on the national territory a few months apart; — possibility of annual updating, due to the annual update of the national satellite coverage, and the use of automated means; — limited costs (satellite images are available free of charge to institutional users, and process automation reduces the human time required for photo-interpretation methods, for example); — response to a first level of needs (zero status of the “natural frame” and “urban reinforcement”, quantification of the distribution of urban or natural areas, quantification of the effectiveness of different planning measures taken, etc.) It is presented in 7 soil cover classes: Anthropogenic Surfaces, Transport Infrastructures, Nude Soils, Water Surfaces, Eternal Snows and Glaciers, Woody Vegetation and Non-wood Vegetation. The product is delivered in vector format with a minimum collection unit (UMC, size of the smallest polygons) of 500 m². This transition from a 5 m resolution image to a 500 m² UMC implies a generalisation of the geometry of the objects represented which is particularly noticeable on the linear elements of the landscape (discontinuity of the road network in particular). When available, the usage information is also specified in a 25 m² raster layer. It is divided into 6 classes: Agriculture, Mines and Quarries, Secondary, Tertiary or Residential Production, Routier, Ferré, Air. The product is delivered by department, according to the right-of-way defined in the CARTO® BD (homogenisation in progress, the Drôme department having been delivered on the GEOFLA® right-of-way).