In early February, Deltares’ Deltaflume carried out wave tests to investigate the strength of a self-closing flood barrier that will be built along the renewed Scheldt quays in Antwerp. The self-closing flood barrier is hidden underground and rises only in cases of high water levels.

The tests went well, which means that the concept of the self-closing dam is ready to protect Antwerp from flooding caused by storm tides on the Scheldt.

As part of the Sigma Plan, which protects Flanders against flooding from storm tides, De Vlaamse Waterweg nv has spent the last few years systematically renovating and stabilising the historic quay wall along the Scheldt in Antwerp. This quay wall is up to 120 years old in places, and is in need of stabilisation or renewal.

The current dam construction, a 1.35 metre-high concrete wall that protects the city during storm tides when the Scheldt rises above the blue stone, is also in need of renewal. The flood barrier needs to be raised by 90 centimetres, in part due to sea level rise.

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Tests in the Deltaflume

Deltares experts constructed a 5-metre-long section of the Antwerp self-closing flood barrier into the Deltaflume. The Deltaflume, a unique research facility 300 metres long, 5 metres wide and 9.5 metres deep, is ideally suited for this purpose because it allows the barrier to be examined at full scale.

This also allows the loads on the barriers to occur at full scale. Several types of tests were conducted, including examining if the self-closing barrier was properly raised and lowered during successive tidal cycles.

The amount of water passing the sealing rubbers was also measured. Large loads were unleashed on the barrier in the form of large waves for several hours, and an object weighing hundreds of kilograms was thrown against the barrier.

The final test was the wave test in which waves, designed to simulate a northwest storm on the Scheldt, were launched at the dam wall. The barrier performed well on all counts.

Technical feat

‘Significant parts of the historic quay wall have already been stabilised,’ says Chris Danckaerts, managing director of De Vlaamse Waterweg nv. ‘In a number of places, the quay wall has already been adapted and integrated in the public space in various ways. In the future, this self-closing water barrier will be added over a distance of 842 metres in the zone between the Zuiderterras and the Bonapartedok.’

He adds: ‘The self-closing flood barrier is a technical feat and a paragon of Flemish innovation, designed to protect Antwerp from the waters of the Scheldt during storm tides. The spectacular test in the Deltaflume simulates conditions similar to a real storm and the flood barrier passed the test with flying colours. This is an important milestone within the works of the Sigma Plan on the Scheldt Quays.’

Views preserved

The self-closing flood barrier will rise only during storm tides. In this way, the view of the Scheldt will be preserved and the public space will remain accessible. It will be the longest self-closing water barrier in the world. The self-closing dam is a Flemish innovation, and will be build by the Belgian company Aggéres.

The construction will be completed in 2028.

Picture by Deltares.

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