3D mapping

Defining the subsurface in models

Three-dimensional maps make it possible to traverse the subsurface in all directions. In our models, we connect data obtained from boreholes and geothermal doublets, for example, as well as from borehole logs. We also acquire geophysical data ourselves through, for example, electromagnetic measurements. Using geostatistical techniques, we’re able to find the correlations hidden within these huge data sets. This allows us to predict what these diments between the data points look like. The more information we have, the more detailed the map. In this way, we’re also able to disclose the deep subsurface, for which relatively little data is available. Part of our 3D mapping is done within the framework of our statutory task of subsurface modelling.

Answer more questions in 3D

We work together with various stakeholder groups, who make their wishes known to us. The easy adjustability of 3D maps allows GDN to answer their questions about recent changes in the soil and subsurface, such as subsidence, its causes and consequences. Additionally, it is becoming easier to connect the land and sea, enabling our models to answer new questions about the use of the subsurface in coastal areas for the construction of wind farms, for example.

Working in 3D yourself

The subsurface can easily be viewed in 3D in your own GIS system or via your internet browser, thanks to the BRO 3D web services. There is also the SubsurfaceViewer: free professional software to view subsurface models in 3D on your own computer. As with the 3D web services, you can combine that with your own data. The SubsurfaceViewer and model files for use in the SubsurfaceViewer can be selected when downloading DGM, REGIS II, GeoTOP or DGMdeep through DINOloket or BROloket.

Cut-outs for specific purposes

Our models can be used to create cut-outs for specific purposes, such as the sandy gully systems of the Rhine and Maas rivers in the covering layer of South Holland, which was formed during the Holocene. The model subsequently shows at which locations and different depths continuous sand layers (‘channels’) surrounded by clay and peat occur, while also providing information about the grain size distribution of the sand.

Top 50 metres in detail: GeoTOP

The GeoTOP model is especially used for issues related to infrastructure and the extraction of sand and gravel. GeoTOP provides a detailed three-dimensional image of the shallow subsurface, up to a depth of 50 metres below the Dutch Ordnance Datum (NAP). This is the part of the subsurface most intensively utilised by humans. GeoTOP is a refinement of the upper part of the moderately deep models, DGM and REGIS II. In GeoTOP, the Dutch subsurface has been divided into millions of voxels (a unit of volume) measuring 100 x 100 x 0.5 metres. Each voxel contains information about the type of soil and its associated physical and chemical properties.

NL3D is another (nationwide) model that offers a low-resolution alternative to GeoTOP with voxels measuring 250 x 250 x 1 metres. NL3D provides information about the soil profile up to a depth of 50 metres for the whole of the Netherlands.

Upper 500 metres: DGM and REGIS II

The Digital Geological Model (DGM) is a regional-scale layer model of the subsurface of the Netherlands to a depth of 500 metres. The geological layers in this depth interval consist mainly of unconsolidated sediments such as clay, sand and gravel. They have been classified into lithostratigraphic units on the basis of their lithology and other rock properties. DGM provides insight into the geometry and spatial relationships of these lithostratigraphic units. In this model the base and top of the units are displayed by depth maps. The thickness of the units is derived from the grid maps of the surface and the base.

The REgional Geohydrological Information System (REGIS II) is of importance for provinces, regional water authorities and drinking water companies. REGIS-II is the hydrogeological refinement of DGM in which each lithostratigraphical unit is subdivided into layers with high hydraulic conductivity (sandy layers, aquifers) and layers with low hydraulic conductivity (clayey layers, aquitards). These layers have been assigned geohydrological parameter values for use in groundwater flow studies.

GeoTOP, DGM and REGIS II are part of the Key Registry of the Subsurface Act. Information about these models can be found on BROloket (in Dutch) and on DINOloket (in English).

Deep range: DGM-deep

Our deep model DGM Deep provides the basis for calculating the potential of geothermal energy and serves as framework for information about conventional energy. It reaches depths of over 7 km. The model is of importance for all mining activities in our country. To date, its primary application was in oil and gas exploration. Nowadays, it also contributes to the energy transition: the model can be used to estimate from which water-bearing layers – aquifers – geothermal energy can be extracted.

Knowledge for applications

Information derived from our mapping can also be found via various tools that we offer. Examples include Delfstoffen Online (Surface Mineral Resources Online, website Delfstoffen Online in Dutch), which contains information about the total and extractable amount of sand and gravel. On the Groundwater Tools website, which shows the Groundwater Levels and Groundwater Quality (website in Dutch), we offer knowledge that can be used to set up a sustainable water supply for citizens, industry and agriculture.