Precision work on the Eastern Scheldt Barrier
A large part of the Netherlands is below sea level. Which is why Rijkswaterstaat works day in, day out to protect against high water levels. Our measures include the Delta Works, the largest of which is the Eastern Scheldt storm-surge barrier. How do we work together to ensure that it functions most efficiently and effectively?
The Eastern Scheldt Barrier is 9 km long and consists of 65 pillars and 62 sluice gates. The barrier is closed during high tide or in the event of extremely polluted waters. If the Eastern Scheldt Barrier fails, a large part of the Netherlands could be flooded: areas of the provinces of Zeeland and North Brabant, such as the Biesbosch. It is therefore truly essential that the barrier remains in top condition.
When the water comes
On average, once a year, storms on the Dutch coast are so severe that expected water levels threaten to rise more than 3 m above NAP (the NAP Amsterdam Ordnance Datum level of zero is about equal to the average sea level in the North Sea).
When water levels are forecast to reach 2.75 m, the Eastern Scheldt Barrier Operations Team is called into action. Marc Walraven, Senior Advisor on storm-surge barriers, explains how this works: ‘We can see about 16 to 24 hours in advance that we may need to close the flood defences. The action-stations level of 2.75 helps to ensure that everyone is on site on time to commence activities for the closing process. The experts within Rijkswaterstaat and the market regularly train for this and build up the necessary knowledge and experience in daily management and maintenance. For them, closing the flood defences is a great day’s work, and also an ideal moment to train and gain experience under storm conditions.’
Emergency systems
Normally, the closing process is initiated manually. If that does not work for any reason, there is always the emergency locking system.
Walraven: ‘We have investigated all kinds of different circumstances that might arise and developed possible work instructions, which we train and practise. With a storm-surge barrier such as the Eastern Scheldt Barrier, you don’t want to leave anything to chance. Nor unforeseen circumstances, such as a malfunctioning sluice gate. We are prepared for anything or have trained staff on site who will take appropriate action based on their expertise.’
Maintenance is crucial
Maintenance is crucial for proper preparation. Every year, outside of the storm season, meaning from 1 April to 1 October, we work hard on various maintenance projects. These are large and small projects, both obvious and less obvious.
Astrid Ghering-van Duijn, Area Manager of the Eastern Scheldt Barrier: ‘In 2025, we worked on around 45 projects. From replacing the fire-alarm system to replacing the working mechanisms. The latter is particularly impactful. It involves removing and refitting cylinders, and that will continue for about twenty years. We have 126 cylinders and are currently refitting four per year. We need to increase that to eight. And then we’ll probably have to start all over again. We see the same thing with the sluice gates. We have painted them over the past ten years, but the first ones are already due for another coat.’
Nothing left to chance
To ensure that everything is well maintained and remains that way, we constantly monitor the condition of the barrier. We examine the concrete, the steelwork and the pipes that run all over the place. Operating systems are also covered. We commenced construction of the barrier in 1976.
The aim was for the barrier to last 200 years. We are currently assessing whether or not that is actually the case. Ghering-van Duijn emphasises once again that we leave nothing to chance: ‘We check everything in detail. We cannot afford any surprises when it matters most, during the storm season, of course. That is why we conduct trial closures several times a year. Even then, we take all details into account. The barrier was originally built to protect nature in the Eastern Scheldt, so trial closures take place during the turning of the tide. This way, the flow of the water is not impeded and nature is not affected.’
Human endeavour
The proper functioning of every storm-surge barrier depends on a perfect combination of maintenance and training. Maintenance alone is not sufficient. The Operations Team members are invaluable, Walraven emphasises:
‘Our people have a great responsibility, and that role is not one that suits everyone. That is why we want to focus on becoming a continuous-learning organisation and are working on the Storm Surge Barriers Learning Centre for all six storm-surge barriers. Without the expertise of those involved, the Eastern Scheldt Barrier cannot function reliably.’