What we do

Challenge

Maintenance dredging and deepening in the navigation channel of the River Scheldt between Vlissingen and the sea lock at Wintam (Hingene). The River Scheldt is a tidal river characterized by strong currents, shallow sandbars and busy traffic.

The River Scheldt is the only maritime access to the Port of Antwerp so plays a vital role in the economy. Given its strategic importance, the Flemish Government guarantees a minimum depth for seagoing vessels along the trajectory towards the port.  However, as there is a constant process of sedimentation, maintenance dredging is crucial all year round. As vessels are getting larger, several deepening dredging campaigns have been necessary in the past.

Maintenance dredging River Scheldt - Pallieter

Solution

DEME has been providing solutions for the sedimentation build up in the river for decades – actually without interruption since 1930. On the bars of the Dutch sector of the River Scheldt, the sediment mainly consists of sand with average grain sizes varying between 150 and 200 micron. In the Belgian sector of the river, the dredged spoil consists of fine sand mixed with a varying volume of mud, depending on the season. While in the Western section of the Scheur (North Sea) we mainly dredge sand. Our trailing suction hopper dredgers dredge an average quantity of 14 million m³ of material per year.

Over the last 25 years sand coming from our dredging works has been used for the hydraulic reclamation of the polder areas in order to obtain additional industrial sites on the right and left bank of the River Scheldt and for the construction of the embankment and foundations of highways.

While within the framework of the Delta Works in the Netherlands and the Sigma flood protection plan in Belgium, several million cubic metres of sand from the dredging works were used to reinforce and raise the dykes.

However, in the most recent years, the vast majority of the dredged sand stays in the tidal system – by preference in the flood channels - in order to guide the river through the main channel and avoid oblique currents over the sand bars.

We also dump sand in the deepest sections of the main channel and also along some banks to stop erosion and to increase the radius of the main channel in the bends. In order to maintain the dynamic equilibrium of the river system, the annual volume evacuated is limited to the estimated amounts of solids conveyed by the sea and deposited on the riverbed.

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