Order 5 Groundwater Body

A body of groundwater is a distinct volume of groundwater within one or more aquifers. Groundwater bodies are derived from work carried out on the BDRHF v1 repository. The cut-off for water bodies follows the following key principles: — Water bodies are demarcated on the basis of geological and hydrogeological criteria, — The redistribution of water bodies to take account of the effects of anthropogenic pressures must remain limited. — The boundaries of water bodies must be stable and durable — Like surface water bodies, the demarcation of groundwater bodies is organised from a typology. This typology is largely based on that developed for hydrogeological entities defined as part of the revision of the RHF BD. It is based on the geological nature and hydrodynamic behaviour or “big” functioning of aquifer systems (nature, flow rate). It has 2 levels of characteristics (main and secondary). — Water bodies may interact with each other — All abstractions providing more than 10 m³/day of drinking water or used to supply water for more than 50 people must be included in a body of water — Deep groundwater, unrelated to rivers and surface ecosystems, from which no sampling takes place and which is not likely to be used for drinking water because of their quality (salinity, temperature?), or for technical and 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. (source: BRGM, WFD IMPLEMENTATION: Identification AND DELIMITATION OF SOUTERRAINE WATER MASSES — methodological guide, January 2003)地下水水体（groundwater body）是指赋存于一个或多个含水层（aquifer）中的独立地下水体。本数据集的地下水水体源自BDRHF v1版本库的相关研究工作。 地下水水体的界定遵循以下核心原则： —— 依据地质与水文地质（hydrogeological）标准划定地下水水体； —— 因人为压力（anthropogenic pressure）影响需调整地下水水体范围时，其重新划分幅度应保持适度； —— 地下水水体的边界须稳定且持久； —— 与地表水水体一致，地下水水体的划定依托分类体系开展。该分类体系主要参照为RHF BD修订过程中定义的水文地质实体所制定的分类框架，其依据为含水层系统的地质属性、水动力特征或“整体”运行机制（包括属性、流速），且包含两级特征参数（主特征与次特征）； —— 地下水水体之间可相互作用； —— 所有日取水量超过10立方米的饮用水取水工程，或服务人口超过50人的供水取水工程，均须纳入某一地下水水体范畴； —— 与河流及地表生态系统无关联、未开展采样工作，且因水质问题（如盐度、温度）或技术经济因素（取水成本过高）无法用作饮用水的深层地下水，可不纳入地下水水体范畴； —— 受自身规模影响，地下水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（spatial heterogeneity）； —— 同一空间点位可叠加存在多个地下水水体。 （来源：法国地质与矿产研究局（Bureau de Recherches Géologiques et Minières, BRGM），《水框架指令（Water Framework Directive, WFD）实施：地下水体的识别与划定——方法学指南》，2003年1月）