HCOV_0900, Ieperian Aquitard System Prevention Area

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. This hydrogeological main unit is formed by the most important part of the Ypres Group. This is the better known Ypres clay. It contains the Silt of Kortemark, belonging to the Formation of Tielt, and the various clay layers of the Formation of Kortrijk. Overall, the Ieperian Aquitard system forms a highly impermeable layer.