What is going on......
Early in the morning somewhere in Normandy...... No birds are singing, except a woodpecker in the distance. Everybody is asleep. Or, almost everybody.
People working.
A hole appears........
And mysterious engineering concepts are set up.
And suddenly, in the middle of nowhere, Dutch vegetation promises sustainable future in France.
BONSAI is testing Dutch Clay with Grass cover in the weather conditions of France.
From the Netherlands to France:
Dutch Dike Cover Put to the Test
How will the grass cover of a Dutch dike cope with the warmer and drier climate we expect in the decades ahead? Within BONSAI, we do not have to wait for the climate to change to find out. Instead, we take the dike to a different climate.
In August 2026, two blocks of Dutch soil with their vegetation intact were transported from the Netherlands to Normandy in France, where our partner Cerema with the research team ENDSUM placed them in the ground. The clay blocks were taken from a dike of Waterschap Brabantse Delta, one of BONSAI's associated organisations, which kindly made them available for this experiment.
The idea came from Rijkswaterstaat, which wanted to know how Dutch dike cover would hold up under different climate conditions. Waterschap Noorderzijlvest and Cerema worked out how to turn that idea into a real test, from cutting and transporting the blocks to placing them at their new location.
In Normandy, the clay blocks will be exposed to different weather conditions than at home. By following how the vegetation and soil develop there, we learn how well Dutch grass covers can withstand a changing climate. The experiment is part of BONSAI's work on the long-term resilience of flood defences, to which the Meegroeidijk project of Noorderzijlvest also contributes (read more about the Meegroeidijk).
This experiment shows one of BONSAI's core ideas in practice: simulating shifting climate zones. By exposing northern dike materials to southern conditions, we learn today what our flood defences may face tomorrow.
The ENDSUM research team
A lot of planning and time was put into this experiment. The teams of Cerema and Noorderzijlvest together with the contractor did a great job.
Crane and Grass
Before the blocks can be placed. Careful transport and handling of the soil with grass is essential.
The real test starts
Now the clay with the grass cover has arrived the real test begins.
Good luck in your new home
Stay tuned for the outcome of this experiment
