Groundwater

Groundwater

The composition of the subsurface has a great influence on the levels and quality of groundwater. The Geological Survey of the Netherlands (GDN) is the foremost institute in the Netherlands bringing together geological information and groundwater-related issues. We, for example, offer our expertise in relation to the use of our land surface, our sustainable drinking water supply, renewable energy, and other applications.

Groundwater levels 

GDN carries out research into the variation of groundwater levels and publishes its results on the website Grondwaterstanden in beeld (‘Groundwater Head Viewer’). Spatial variations offer insight into the flow of groundwater. The horizontal flow direction can be deduced from so-called ‘isohypses’, the lines of equal groundwater levels. Vertical differences in groundwater levels indicate the presence of clay layers in the subsurface, which have a protective effect on drinking water supplies, for example.

Variation over time is important for the availability of water and land use, for which the soil should neither be too wet nor too dry. In the Netherlands, precipitation and evaporation strongly influence groundwater heads. The response of the head is a kind of signature of the groundwater system, which GDN also uses to better understand the functioning of that system.

Quality of groundwater

Substances, both of natural origin and resulting from human activity, are dissolved in groundwater. Our research shows which substances enter the soil with the rainwater, how dissolved substances penetrate and spread in the soil, and which processes take place in the subsurface. This is relevant, for example, to nature and our drinking water. We also look at the age of groundwater (how long it has been in the ground), which can vary from a few weeks to thousands of years. Check the groundwater quality on the website Grondwaterkwaliteit in beeld (‘Groundwater Quality Viewer’).

Impact of subsurface energy applications

Regarding aquifer thermal energy storage (ATES), water in the shallow subsurface (up to a depth of several hundred metres) is used to store heat. In addition, hot water in the deep subsurface can be used for geothermal heat (i.e.  geothermal energy). When pumping up both shallow and deep water, it is important to protect the quality of the shallower groundwater. We are investigating the potential negative impact of aquifer thermal energy storage (ATES) and geothermal wells on the quality of groundwater. A system of permits and monitoring will remain important if geothermal energy is to play a greater future role in our energy system.

Groundwater requires collaboration

Within the realm of groundwater, GDN collaborates with other research institutes and consultancies. Deltares, for example, uses the groundwater data from Grondwaterstanden in beeld (‘Groundwater Head Viewer) and Grondwaterkwaliteit in beeld (‘Groundwater Quality Viewer’) together with our subsurface models, for the national groundwater model of the Netherlands Hydrological Instrument (NHI). Our hydrogeological model, REGIS II, provides information on the structure and permeability of the subsurface. Our model, GeoTOP, offers more detail for the upper 50 metres. These groundwater models, in turn, supply information that we can use.

More information

Would you like to know more about our contribution to research on groundwater levels and quality? Contact Willem Jan Zaadnoordijk via the blue ‘mail directly’ button below.