Elementary polygons of groundwater bodies — France as a whole — Version Report 2016

A groundwater body is a separate volume of groundwater within one or more aquifers, constituting the elemental division of aquatic environments intended to be the WFD assessment unit. It makes it possible to define environmental objectives, to assess the state of the environment and subsequently to verify the achievement of these objectives. Groundwater bodies were the subject of the 2016 report to the European Commission on the implementation of the WFD. The layers are distributed in a format consistent with the SANDRE data dictionary of the Water Mass Reference, version 1.3. The splitting used for water bodies meets the following main principles: Water bodies are delimited on the basis of geological and hydrogeological criteria, The redividing of water bodies to take account of the effects of anthropogenic pressures must remain limited. Water body limits must be stable and sustainable Like surface water bodies, the delimitation of groundwater bodies is organised from a typology. This typology is largely inspired by the one developed for the hydrogeological entities defined as part of the revision of the RHF BD. It is based on the geological nature and hydrodynamic behavior or “big” operation of aquifer systems (nature, flow velocity). It includes two levels of characteristics, main and secondary. Water bodies can have exchanges between them. All Potable Water Supply Captures, providing more than 10 m³/day of drinking water or used for water supply to more than 50 people, must be included in a water body. Deep groundwater, unrelated to rivers and surface ecosystems, in which no sampling takes place and which are not likely to be used for drinking water due to their quality (salinity, temperature, etc.), or for technical and economic reasons (disproportionate cost of capture) may not constitute bodies of water. Given its size, a body of water may present a certain spatial heterogeneity both in terms of its hydrogeological characteristics and its qualitative and quantitative state. At any point several bodies of water can overlap. The PolygMasseDEauterraine layer results from the agglomeration in a single file, of all groundwater bodies divided into elementary multipolygons corresponding to each of their depth levels. The entire national territory is covered, the polygons overlap. In other words, if one seeks to identify the water bodies present at a point in the territory, this layer will be able to make 1 to 10 water bodies differentiated only by the associated superposition order. In accordance with the SANDRE V1.3 data dictionary, the layer is composed of the same attributes as the MasseDEauSouterraine layer with: — The addition of the “Level” field: Depth level of the elementary multipolygon of the groundwater body; — The addition of the field ‘CdPolygMasseDEauSouterraine’: Unique code of the elementary multipolygon of the groundwater body.