Involved from start to finish
Expert(s) |
Arne van der Hout
Just before the commissioning of de Nieuwe Sluis in Terneuzen, researchers from Deltares cross the lock chamber in a small boat. On the hottest day of the year, with temperatures reaching 38 degrees Celsius, Arne van der Hout and Jelle Molenaar remove the forty measuring instruments that have been measuring the density of the water for a month and a half. Not long after, the first ships pass through the lock.
Commissioned by Rijkswaterstaat, Deltares investigated the interaction between fresh and salt water in the lock in the summer of 2025, before it became operational. The large ships passing through the lock cause salt water from the Westerschelde to flow into the fresher Ghent-Terneuzen canal. Because salt water is heavier than fresh water, a current is created in the lock. This can cause problems for ships and their pilots during lockage, as this density current can exert considerable forces on the ships.
‘The lockage time was determined in previous research, and with these current measurements we are checking whether this is happening as planned and whether it is proceeding safely,’ says project leader Arne van der Hout, hydrodynamics and hydraulic engineering expert at Deltares.
Mooring force
“Our analysis is important for the pilots, who have to be able to safely guide the enormous ships in and out of the lock,” says Arne. Together with Rijkswaterstaat, the pilotage service and the boatmen, Deltares also investigated the force exerted by the water on the ships: by measuring the forces in the mooring lines. ‘These lines are the critical links during mooring in the lock,’ explains Arne. ‘The lock at Terneuzen is comparable in size to the Panama locks, so the ships that pass through here are enormous. They must be held in place by mooring lines when there is a current.’ The mooring force measurements were carried out by Rijkswaterstaat itself, and Deltares processed the data in the analysis. The insights gained from the measurements help to moor ships safely and allow them to pass through the lock.
Arne and his colleagues Nino Zuiderwijk and Marjolijn Mascini also use this data to validate the Deltares models that simulate specific processes in lock chambers. ‘Our WANDA model, for example, shows how long it takes for the lock to fill up and empty again,’ explains Arne. Ultimately, the Deltares analysis of the dynamics of the water serves primarily as a guideline on which Rijkswaterstaat can base lock regulations and guidelines for pilotage. ‘Thanks to our knowledge, they know what to expect under certain circumstances and which measures are effective,’ says Arne.
Scale models
Deltares' involvement in de Nieuwe Sluis dates back to 2016. In the experimental facilities, Arne and his colleagues tested the effects of density currents in scale models of the lock. They looked at the ideal lockage times, during which ships can pass through the lock safely. Based on these scale models, the design was optimised and it was determined that the hydraulic design met the requirements set for it.
The New Lock was built to improve access and facilitate smoother traffic flow from the Westerschelde to the Ghent-Terneuzen Canal and beyond. Waterway capacity has also increased, reducing waiting times for inland vessels.
Long-term involvement
Arne explains that Rijkswaterstaat specifically approached the experts at Deltares who had worked on the earlier research during the design of the lock. “As project leader, I have been involved in this lock from the outset, from the preliminary studies and designs to the construction. As a result, we know exactly how, what and where we need to measure. I see it as a challenge to safeguard the knowledge that has been developed throughout the project.”
Rijkswaterstaat has confidence in us because we have been involved in this lock from its development to its operation in practice
Arne van der Hout, expert hydrodynamics and hydraulic engineering
In five weeks, the Deltares team travelled to Terneuzen six times, where they sailed through the approach harbours and into the lock chamber together with the boatmen. Forty ‘ctd divers’ at various locations logged the conductivity (which indicates whether the water is fresh or salt), temperature and pressure. Arne: ‘These divers hang underwater and log autonomously on their internal memory. After a week, it is full, so you have to empty it, clean it, check it and reattach it.’
This is no hardship for Arne, because he believes this fieldwork contributes to better analysis. "You get a better feel for the scale on site and you see different situations, such as what actually happens during lockage. It's great to have contact with the people who work there, the lock operators and the pilots. Because you can read the data directly and check it on the spot, you obtain more accurate and reliable data."
Tangible results
For Arne, these kinds of projects are the icing on the cake: ‘It's wonderful to be able to create these kinds of hydraulic structures, to have a tangible result of your work. A lock like this is built to last a hundred years, and you've contributed to that. I'm quite proud of that.’
