REGIS II, A 3D HYDROGEOLOGICAL MODEL OF THE NETHERLANDS

Up to the late 80's, hydrogeological information of the Dutch subsurface used to be presented in the form of maps as part of the “Grondwaterkaart van Nederland” (Groundwater Map of The Netherlands). In the early 90's, a first set of digital subsurface models and maps was developed for groundwater management as part of the so-called REgional Groundwater Information System (REGIS I). Based on experience gained with these models, a fully revised mapping concept was developed which resulted in the release in 2005 of REGIS II, comprising of a 3D hydrogeological model of the Dutch subsurface describing the geometry and hydraulic properties of so-called hydrogeological units, and 11 regional, so-called geohydrological models describing the geometry and hydraulic properties of aquifers and aquitards in each province.

Hydrogeological units, rock bodies with more or less uniform hydraulic properties, play a key role in this new concept. These units are defined based on lithostratigraphy, primary lithology and associated hydraulic properties and stratigraphic position. A hydrogeological model is simply defined as a spatial interpretation of the subsurface into hydrogeological units.

The hydrogeological model is based on the new lithostratigraphical scheme as well as the new Digital Geological Model of The Netherlands. It covers 106 units within the uppermost 500 meters of the subsurface. Maps of the geometry and hydraulic properties are available in the form of grids.

A big advantage of this new concept is that schematizations of the subsurface in aquifers and aquitards (so-called geohydrological models) can easily be derived from this hydrogeological model by combining the digital map data from the units. Depending on the goal for which the data are needed, f.e. a groundwater model, a coarse or highly detailed geohydrological model can be created for any area, still ensuring consistency between the data. For eleven (out of twelve) provinces a geohydrological model was created.

All models are accessible through the internet at www.dinoloket.nl.