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Understanding Seabed Recovery After Sand Extraction in the North Sea

In medium-deep sand extraction, all existing seabed life within the extraction area is removed. What remains is a sand extraction pit without living organisms. After this, a natural recovery process begins. Sand and silt gradually settle back into the pit, and over time seabed life slowly re-establishes itself. Eventually, a new benthic community develops — but exactly how fast and in what way this happens is still not fully understood. OR ELSE researchers are contributing to research within the Rijkswaterstaat programme Zand uit Zee to better understand how this recovery process unfolds.

Measurements near Ameland

North of Ameland, Rijkswaterstaat is closely monitoring a six-metre-deep sand extraction pit. This is being done through a so-called Before After Control Impact (BACI) study. This means that conditions before, during and after sand extraction are compared with areas where no extraction takes place.

The research began in January 2025 with sampling of the existing benthic fauna community and measurements of current velocities, waves and turbidity. In December 2025, the sand extraction pit was completed by Boskalis. Last January, one year later, new benthic fauna samples were collected to document the situation directly after extraction, while current velocities, waves and turbidity are now also being measured within the new pit. These measurements will continue over the coming years, gradually providing a clearer picture of how the seabed recovers in both the short and long term.

Collaboration between research institutes

This research generates large amounts of monitoring data. For the analysis, Rijkswaterstaat collaborates with several research institutes:

  • TU Delft analyses multi-year sensor data collected on the seabed
  • Deltares investigates changes in depth and seabed composition
  • NIOZ and Wageningen Marine Research analyse the development of benthic communities

Together, they are mapping how sand extraction affects the North Sea seabed and how recovery processes take place.

Why is this important?

The results of this research will provide greater insight into how sand extraction can be carried out in the future. This will help us better align coastal protection and nature conservation.