The challenge
Griend is a vegetated sandbank in the Wadden Sea with a unique flora and fauna. The uninhabited island provides an important habitat for many waterbirds, seals, and insects. Due to coastal erosion, severe wear, and continuous geomorphological changes, Griend has been under pressure for decades. Without additional coastal protection, the island risks being swallowed by currents and waves.
To preserve the island’s ecological value, vegetation management and sod cutting were carried out. In addition, a new sand motor was created using sand from the sea channel known as the Blauwe Slenk. A sand motor is a large volume of sand that gradually spreads along the coastline through wind, waves, and currents to reduce erosion and protect natural areas. Shell banks were also constructed, creating an attractive habitat for small aquatic species.
On Griend, nature is in control. Thanks to the restoration works, the bird island has been saved for the next 25 years.
Unique collaboration
Rijkswaterstaat Zee en Delta, the Dutch Ministry of Infrastructure and Environment, commissioned Walhout to prepare the contract, provide tender support, and advise during project execution. The project was accelerated and successfully completed within just a few months. Close collaboration took place with contractor Boskalis and various stakeholders. Walhout carefully translated all requirements and stakeholder interests into a successful contracting and execution process. Following an efficient realization, the project was handed over to Natuurmonumenten, ensuring that Griend will remain protected and safeguarded for years to come. What makes this project particularly unique is that the island is normally a restricted area, accessible only to the site managers of Natuurmonumenten.
Our activities
- Stakeholder identification and client consultations
- Preparation of client and system requirements
- Preparation of E&C contract specifications
- Preparation of the integrated safety plan
- Review and verification of the sand engine design
- Member of the contract assessment committee
- Execution meetings on Griend
- Technical consultancy
- Assessment of the completion dossier
Building with nature
Griend plays an important role in achieving the Natura 2000 objectives. For this reason, the project adopted practical solutions based on the principles of “Building with nature”. During execution, the enhancement of flora and fauna, ecology, and the natural development of the area remained central.
In the coming years, the University of Groningen, Radboud University, and the Royal Netherlands Institute for Sea Research (NIOZ) will study how nature and morphological processes on Griend continue to develop. This knowledge will contribute to a better understanding of the dynamics of the Wadden Sea.