Elementary polygons of groundwater bodies — Meeting — State of Places version 2019

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. Groundwater bodies are derived from work carried out on the BDLISA repository. The splitting used for water bodies meets the following main principles: — Water bodies are delimited on the basis of geological and hydrogeological criteria; — The redivision of water bodies to take account of the effects of anthropogenic pressures must remain limited; — The limits of water bodies must be stable and durable; — Similar to 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 in the framework of the revision of BDLISA. It is based on the geological nature and hydrodynamic behavior or “big” operation of aquifer systems (nature, flow velocity). It comprises 2 levels of characteristics (main and secondary); — Bodies of water may have exchanges between them; — All water withdrawals for drinking water supplying more than 10 m³/day or used for the supply of water to more than 50 persons must be included in a body of water; — 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 because of their quality (salinity, temperature, etc.), or for technical and economic reasons (disproportionate cost of abstraction) may not constitute bodies of water; — 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 state; — At any point several bodies of water may overlap. (source: according to BRGM, DCE IMPLEMENTATION: Identification AND DELIMITATION OF SOUTERRAINE WATER MASSES — Methodological Guide, January 2003) The layers are distributed in a format consistent with the SANDRE data dictionary of the Water Mass Reference, version 1.4.地下水体是指赋存于单个或多个含水层内的独立地下水体积，是水生态环境的基础划分单元，拟作为水框架指令（Water Framework Directive, WFD）的评估单元。 地下水体数据源自BDLISA数据库的相关研究工作。 地下水体的划分遵循以下核心原则： — 水体以地质及水文地质条件为依据进行划定； — 为体现人为活动压力影响而对水体进行的重新划分应严格受限； — 水体边界需保持稳定持久； — 与地表水体类似，地下水体的划定基于类型学框架。该类型学很大程度上借鉴了BDLISA修订框架中定义的水文地质实体类型学，以含水层系统的地质属性、水动力特性或“宏观”运行特性（如介质性质、水流速度）为划分依据，包含两级特征参数（主特征与次特征）； — 不同地下水体之间可存在水力交换； — 所有日取水量超过10立方米或供水规模超过50人的取水工程，均需纳入对应地下水体的管理范畴； — 与河流及地表生态系统无关联的深层地下水，若未开展采样工作，且因水质（盐度、温度等）或技术经济原因（取水成本过高）不适用于饮用水供水，则可不划定为地下水体； — 受自身规模影响，地下水体在水文地质特征、水质与水量状态上可能存在一定空间异质性； — 同一空间点位可与多个地下水体重叠。 （数据来源：源自BRGM编制的《DCE实施：地下水体识别与划定方法学指南》，2003年1月） 本次数据集的图层采用符合SANDRE《水体参考数据词典》1.4版的格式进行分发。