How high is the salt content in the Northern Drenthe soil, but especially how thick are our clay layers? The Fresehm-NL investigation should soon show that. The way in which the research is conducted is special.
A helicopter flies about eighty meters above the ground. Dozens of meters underneath hangs a large tube system in the form of a hexagon. Not just a hexagon, it is a measuring instrument that broadcasts a magnetic signal. That signal can recognize different types of soil, clay and water under the ground. With the data, a three -dimensional image is made to more than 200 meters in depth. This gives the researchers insight into the groundwater and the location and thickness of clay layers.
The research is being conducted along the entire Dutch coast and hinterland, including in Groningen and the north of Drenthe. The provinces of Groningen and Drenthe, Water Boards Hunze and Aa’s and Noorderzijlvest, and Waterbedrijf Groningen work together in this. Research is being done in Drenthe in the municipalities of Noordenveld, Tynaarlo, Midden-Drenthe and a part of Assen and Aa and Hunze.
In North Groningen, the research has to do with salinization, especially in the coastal areas. The groundwater there is slowly becoming saltier. In the north of Drenthe there is also research into the salt content in the water, but the cooperating parties want to know more about clay layers here. “Clay layers are important to have a good and detailed picture of. They protect the groundwater against contamination from above,” explains speech food Henry Frieswijk of the Noorderzijlvest water board.
The parties also want to learn more about groundwater flows under these clay layers. “That is important because we can better analyze the consequences of climate change and its effect on the underground water system,” continues Frieswijk. “The data that the project produces help us as cooperating parties in water management.”
It is not yet known when the helicopter will fly above Drenthe. This has to do with weather conditions, among other things. The investigation runs until February next year.
In 2017, a helicopter with the same scanning device was also active in Drenthe. At the time, the subsurface of the Drentsche Aa area was investigated.