Basic polygons of groundwater bodies – Metropole – 2016 Reporting Version

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 assessment unit of the WFD. It makes it possible to define environmental objectives, assess the state of the environment and subsequently 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 conforming to the SANDRE Data Dictionary of the Reference Water Body, version 1.3. The cut-off for water bodies meets the following key principles: Water bodies are delimited on the basis of geological and hydrogeological criteria, The redistribution of water bodies to take into account the effects of anthropogenic pressures must remain limited. The boundaries of water bodies must be stable and durable Like surface water bodies, the delimitation of groundwater bodies is organised from a typology. This typology is largely inspired by that developed for hydrogeological entities defined as part of the revision of the RHF DB. It is based on the geological nature and the hydrodynamic or “large” behavior of aquifer systems (nature, flow rate). It includes two levels of characteristics, principal 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 the water supply of more than 50 people, must be included in a water body. Deep groundwater, unrelated to watercourses and surface ecosystems, in which no sampling takes place and which is not likely to be used for drinking water because of its quality (salinity, temperature, etc.), or for technical-economic reasons (cost of disproportionate abstraction) may not constitute water bodies. Given its size, a body of water may have a certain spatial heterogeneity in terms of both its hydrogeological characteristics and its qualitative and quantitative status. At any point several bodies of water can be superimposed. The PolygMasseDEauSouterraine layer results from the agglomeration into a single file, from 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 can make 1 to 10 bodies of water differentiated only by the associated order of superposition. Compliant with the SANDRE V1.3 Data Dictionary, the layer is composed of the same attributes as the Underground MasseDEau 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.