The model GeoTOP provides a detailed three-dimensional view of the subsurface in the Netherlands until a maximum depth of 50 metres below NAP (Dutch Ordnance Level). GeoTOP schematises onshore Netherlands in millions of voxels (cells), each measuring 100 by 100 metres horizontally and 50 centimetres vertically. Each voxel in the model contains information on the lithostratigraphy and lithological classes, including the probability of occurrence for each lithological class. GeoTOP refines the top of the DGM and of the REGIS II model, providing a sound framework for subsurface-related questions on groundwater management, natural resources and infrastructure.
GeoTOP models individual regions that roughly correspond to provinces. The latest version includes the regions Zuid-Holland, Noord-Holland, Rivierengebied (the Rhine–Meuse area), Westelijke Waddden (Friesland and the western part of the Wadden Sea), Oostelijke Wadden (Groningen and the eastern part of the Wadden Sea), Noord-Brabant and Noord- and Midden-Limburg, Zeeland and Goeree-Overflakkee, and Almere.
GeoTOP does not include the subsurface of the Dutch part of the North Sea.
Detailed information about the development of the model is described in the report Totstandkomingsrapport GeoTOP (PDF in Dutch - 9.9MB) regarding the regions Westelijke Wadden and Oostelijke Wadden. Noord-Brabant and Noord- and Midden-Limburg is described in the report Totstandkomingsrapport GeoTOP - met nieuwe methodiek lagenmodellering (PDF in Dutch - 8.9MB) With this region, a new method for the construction of the layer-based model underpinning the GeoTOP voxel model was introduced. The report Totstandkomingsrapport Kleine release GeoTOP Zuid-Holland (PDF in Dutch – 1.6 MB) accompanies a minor update of Zuid-Holland in which the ‘most likely lithological class’ was recalculated. In addition, an error in the model calculations within the Basal Peat Bed was corrected for. The report Totstandkomingsrapport GeoTOP – aanvullingen bij versie v1.5 (PDF in Dutch – 0.8 MB) describes the update of the Zeeland and Goeree-Overflakkee region. Finally, the report Totstandkomingsrapport GeoTOP – aanvullingen bij versie 1.6 (PDF in Dutch – 1.13 MB) describes the model area Almere and an update of Noord-Holland and Rivierengebied.
Source data
GeoTOP has been constructed per region from the available digital borehole logs stored in the DINO database, which contains some 540,000 borehole logs. For the region Rivierengebied (Rhine–Meuse area), additional borehole logs from Utrecht University’s Department of Physical Geography have been used. The borehole data were supplemented with data from cone-penetration tests and from digitised geological maps.
Application and reliability of the model output
The GeoTOP model provides information on the stratigraphy, lithology and the interrelated physical and chemical properties of the subsurface of onshore Netherlands to a depth of 50 metres below NAP. The model contains as much available data and information on the subsurface as possible, summarised in borehole logs with lithostratigraphic interpretations, a layer model and a voxel model, all of which can be requested via DINOloket.
GeoTOP models the subsurface at a subregional scale that is suitable for applications at the levels of province, municipality and district. This scale is comparable to the 1:50,000 scale used for one of its predecessors, the Geological Map of the Netherlands. If a larger scale is required (when working at the level of streets or individual buildings), GeoTOP can serve as a framework to which more detail can be added.
GeoTOP is broadly applicable for issues in which the stratigraphy and lithology of the shallow subsurface are important, such as groundwater studies, the prediction of land subsidence, insight into the depth required for foundations, the location of sandy channels and the calculation of volumes of natural resources.
More details about the quality of the model can be found in a set of Quality Control documents: Kwaliteitstoetsingsdocumenten GeoTOP (ZIP in Dutch - 5.57 MB).
Current and earlier versions
In the module Subsurface models GeoTOP version 1.6 (2023) is available. Earlier versions can be requested via the contact form.
Reports
A list with reports on this model is available on the Report back page.
3D representation of the GeoTOP model