Helicopter survey maps the subsurface of the northern Netherlands
In the provinces of Groningen, Drenthe, and Fryslân, the subsurface is being mapped using helicopter measurements. The aim is to identify where clay layers are located that protect the underlying groundwater. The collaborating parties also want to know where the fresh and salt groundwater is located in our area. The measurements are part of the national FRESHEM-NL project (FREsh Salt groundwater distribution by Helicopter ElectroMagnetic survey).
Collaboration
FRESHEM-NL is a nationwide collaboration between seven provinces, seven water boards, five drinking water companies, and two knowledge institutes. The provinces of Groningen and Drenthe, the Hunze en Aa’s and Noorderzijlvest water boards, and Waterbedrijf Groningen are collaborating in the Groningen-Drenthe subregion. Together, they are investing more than €850,000 in the research. The results will ultimately be made available to everyone.
Fresh groundwater and salinization
The helicopter measures to a depth of approximately 200 meters. This information is important for water managers, water producers, nature organizations, provinces, and farmers, among others. In coastal areas such as Groningen, the groundwater is becoming increasingly salty. This is partly due to rising sea levels and because salty groundwater from deep polders is flowing upwards. This is called salinisation. Salinisation can have adverse effects on agriculture, nature and drinking water. By accurately mapping where fresh and salty groundwater is located, we can design our water system as intelligently as possible. For example, to ensure the availability of fresh water for the future.
Safe and responsible implementation
During the day, the helicopter flies at an altitude of approximately 80 meters at a speed of 60 to 80 kilometers per hour. A measuring instrument is suspended beneath the helicopter, which emits a harmless magnetic signal. The measurements are safe for humans, animals, and nature. Naturally, flights do not take place during the breeding season, and strict rules apply to nature reserves.
Planning
We believe it is important to inform residents about the flight schedule, which is planned for between August 2025 and February 2026. Once the schedule has been finalized, the collaborating parties will inform the local community.
More information about the project can be found on the Freshem-NL website .