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Topsoil maps out salinization

Many daily activities are inextricably linked to the upper layer of soil. Climate change disturbs the balance between fresh, brackish and salt groundwater. Within this project, VMM studies the relationship between fresh and salt water at the coast and possible ways of improving it.

Topsoil: what and why?

Topsoil is a project under the Interreg VB North Sea Region programme. The project aims to better protect the North Sea Region in the future against the effects of climate change. Many daily activities are inextricably linked to the upper layer of soil. Climate change, in fact, impacts the subsoil and the groundwater at an ever-faster rate.

Purpose of the project

The overall aim of this joint interregional project is to study how we can make the shallow subsoil (30 m upper layer of soil) more resilient to climate change.

The solutions developed will be practically implemented in 16 pilot projects across various regions in the North Sea area.

Topsoil in Flanders

Within this project, VMM focuses on the coastal and polder system. Climate change disturbs the balance between fresh, brackish and salt groundwater. Climate change has a twofold impact:

  • the predicted drier summers will result in an increased need for fresh water, but also in decreased precipitation excess;
  • the rise in sea level will cause the volume of fresh water bubbles in the dunes to decrease and the brackish (saline) pressure in the polders to increase.

This could lead to further salinization and therefore a decrease in freshwater supplies. Knowledge of the degree of salinization is also relevant for future projects and the abstraction of drinking water. 

Our subproject therefore consists of two main parts:

  • mapping out the fresh-salt water distribution with a helicopter;
  • exploratory research into potentials for improving fresh water availability in the shallow subsoil. 

MeasurementsImage helicopter topsoil measurements

The degree of salinization was measured with a helicopter in the summer of 2017. A helicopter flew along lines systematically spaced 250 m apart.  A hoop-shaped measuring probe of 30 by 11 m was attached to the bottom of the helicopter, which flew at a low altitude (65 m) so that the probe hung 30 m above the ground.  The helicopter flew at a speed of 30 to 60 km/h.

The electromagnetic field that was emitted allowed us to gather data on the conductivity of the subsoil. These data enable VMM to determine the degree of salinization of the groundwater in the coastal and polder areas. 

Topsoil in Europe

The Topsoil project has been set up under the Interreg North Sea Region programme. This is a transnational programme aimed at supporting, developing and promoting sustainable economic growth in the participating countries in the North Sea Region. Cross-border cooperation is essential because climate change does not stop at national borders. Details on the project can also be found in this leaflet.


The Netherlands

Waterschap Hunze en Aa's

Waterschap Noorderzijlvest

Provincie Drenthe


Bundesanstalt für Geowissenschaften und Rohstoffe

Dachverband Feldberegnung Uelzen

Landwirtschaftskammer Niedersachsen

Landesamt für Bergbau, Energie und Geologie

Leibniz-Institut für Angewandte Geophysik

Oldenburgisch-Ostfriesische Wasserverband

Landesamt für Landwirtschaft, Umwelt und ländliche Räume Schleswig-Holstein

Universität Bremen Geologischer Dienst für Bremen


Vlaamse Milieumaatschappij


Region Midtjylland (leadpartner)

Region Syddanmark

Herning Kommune

Horsens Kommune

Hydrogeofysik Gruppen, Geoscience Aarhus University

De Nationale Geologiske Undersøgelser for Danmark og Grønland

United Kingdom  

Rivers Trust

Norfolk Rivers Trust

Essex & Suffolk Rivers Trust

Northumbrian Water Ltd.

Durham University

Type project: Interreg VB North-Sea Region

Duration: 01/12/2015 - 01/06/2019 


VMM contributes to the international policymaking and the implementation of environmental obligations.

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