Hydrogeological entities — Métropole

The hydrogeological entity is a part of the geological space, aquifer or non-aquifer, corresponding to a physical system characterised by its state and hydrogeological characteristics. The hydrogeological entity must be understood in a systemic sense and corresponds to a breakdown of the geological space carried out at a given stage of knowledge in particular for deep systems. The constitution of hydrogeological entities is derived from knowledge at a given date of the underground environment (geological map, geological cutting, geological log, structural diagram and piezometric map). Hydrogeological entities can be multi-part. Hydrogeological entities cover the entire territory ensuring a horizontal and vertical relationship of entities in accordance with the principle of completeness. A hydrogeological entity is a part of the geological space: — delimited on a certain scale (level of use) — attached to a type of geological formation (theme) — defined by its aquifer potentialities (nature) — characterised by a type of porosity (mid) — characterised by the presence or not of a tablecloth, which may be free, captive or free and captive (state) They have been defined in accordance with rules developed within the framework of a common national methodology and validated by a national steering committee under the responsibility of the Ministry responsible for the environment. A hydrogeological entity will be represented by its orthogonal ground projection. The reference scale is the 1/50 000th, i.e. the national geological reference scale. Each entity has a code that is assigned by the BRGM (Order of 26 July 2010, SNDE). (According to Sandre, dictionary of the hydrogeological reference SAQ V 2.2)水文地质实体（hydrogeological entity）是地质空间的组成部分，可归类为含水层或非含水层，是一类以自身状态与水文地质特征为核心表征的物理系统。 水文地质实体需从系统论视角进行理解，对应于特定认知阶段下对地质空间的划分，这一点在深部地质系统的研究中尤为突出。 水文地质实体的构成，源自特定时期对地下环境的认知成果，涵盖地质图、地质剖面、地质录井、构造图与测压水位图等资料。 水文地质实体可为多组分结构。 水文地质实体覆盖全域范围，遵循完整性原则，确保实体间建立水平与垂向的关联关系。 水文地质实体作为地质空间的一部分，需满足以下判定条件： — 按特定尺度（使用层级）划定边界 — 依附于某类地质建造（主题） — 以其含水层潜能（性质）进行定义 — 以孔隙类型（介质）为特征 — 以是否存在隔水层为表征，隔水层可分为潜水型、承压型或兼具潜水与承压双重状态 上述实体的定义遵循国家统一方法论框架下制定的规则，并由环境主管部门牵头的全国指导委员会予以验证。 水文地质实体将通过其地面正交投影进行表征，参考比例尺为1/50000，即全国地质参考比例尺。 每个实体均配有由法国地质矿业研究局（BRGM）赋予的专属编码（依据2010年7月26日政令，国家地下水数据与服务系统（SNDE））。 （资料源自Sandre，《水文地质参考词典SAQ V 2.2》）