GeoTOP model extended with south-western part of the Flevopolder
The GeoTOP model has been expanded to include Almere and the surrounding water. This new version of GeoTOP has been available since October 12, 2023.
The expansion of GeoTOP comprises the south-western part of the Flevopolder. It covers the municipality of Almere and the surrounding area, including the surrounding waters. Within this coverage we find housing development areas such as Almere Pampus and Eemvallei Stad, and the route of the planned infrastructural connection between Almere Pampus and IJburg. These additions make the latest version of GeoTOP extra valuable.
Focus on the subsurface of Almere
Water and subsurface are guiding the Municipality of Almere’s Subsurface Master Plan. GeoTOP plays an important role in this plan. GeoTOP’s subterranean model is one of the sources of information that allows land subsidence and water management to be taken into account, thus helping to find suitable locations for extracting or storing geothermal energy.
What is particularly special about this extension of GeoTOP is that the data density of the hand-drilled boreholes is very high compared to other GeoTOP areas. We have been able to make use of both historical information and the most up-to-date data. A good example is the set of about 5,500 historical hand-drilled borehole descriptions from the archives of the Rijksdienst voor de IJsselmeerpolders (RIJP). These drillings were conducted during the first period after reclamation (1968). Because the ground level is now 1 to 1.5 meters lower, these data have been corrected for the land subsidence that followed since.
Small overlap Noord-Holland and Rivierengebied
In this latest GeoTOP version, the model areas Noord-Holland and Rivierengebied have reduced a bit in size. The reason for this is that the new model area of Almere overlaps with the model areas Noord-Holland and Rivierengebied. We now show the most up-to-date information in GeoTOP. Other model areas already present in the previous version (GeoTOP v1.5) remain the same.
GeoTOP is a 3D model of the shallow subsurface, showing the subsurface of the Netherlands up to a maximum of 50 meters below NAP in blocks of 100 x 100 x 0.5 meters. Each block provides information about the layer structure and soil type (sand, gravel, clay or peat). Based on hundreds of thousands of borehole descriptions, the composition and characteristics of the subsurface were estimated for each block.
Since 2020, the GeoTOP model is included in the Subsurface Key Register. This implicates, among other things, that administrative bodies are obliged to consult the model when considering spatial issues.
Towards national coverage of GeoTOP
Parts of the Netherlands are still missing in GeoTOP. In 2023 the Geological Survey of the Netherlands started modelling the shallow subsurface of the IJsselmeer region, Drenthe and Eastern Netherlands (model area ‘Eastern Netherlands’). We expect to publish this large model area in 2026. Last but not east, South Limburg will follow in the years thereafter, resulting in a truly national coverage for GeoTOP.
Want to know more?
View or download the BRO model GeoTOP (version 1.6) with the updated model area Almere on BROloket or DINOloket. It is also possible to download the model there and, for example, use it in your own GIS software. For more information, please contact the Servicedesk.