HCOV_0400, base of the Oligocene Aquifer system

Flanders is made up of an alternation of aquifers (sand, gravel, chalk, solid rock, ...) and regionally occurring non-aquifers (e.g. clay). The sequence of these aquifers and aquitards has its own coding in Flanders: the Hydrogeological Coding of the Subsurface of Flanders (HCOV-coding). The HCOV coding is made up of hydrogeological main, sub and base units. The main unit groups a sequence of geological layers that have broadly the same hydrogeological properties and thus form a single whole. HCOV_0400 (Oligocene Aquifer System) comprises the complete aquifer system between the closing layers of the Boom clay (Formation of Tree) and the Bartoon clay (Formation of Maldegem). This is a sequence of aquifers, whether or not in contact with each other, separated by non-continuous clay layers of limited size. This main unit is formed by the layers belonging to the Formations of Bilzen, Borgloon, Sint-Huibrechts-Hern and Zelzate. The dataset ‘HCOV_0400, basis of the Oligocene Aquifer system’ shows in a grid per grid cell the elevation value (in m TAW) of the lower limit of this hydrogeological layer.