Volkerakdam
The Volkerakdam is more than just a simple dam. It is the largest and busiest inland navigation lock complex in Europe.
The complex forms a tripod between Goeree-Overflakkee, the Hoeksche Waard, and the mainland of North Brabant, separating three bodies of water: the Hollandsch Diep, the Haringvliet, and the Volkerak.
The Volkerakdam in statistics
- Built between 1957 and 1967
- 4.5 kilometers long, with a 1.2 kilometer long bridge
- 48 sluice gates
- 3 large sluices and locks for commercial shipping, 24 meters wide and 330 meters long
- Nearly 150,000 ships and 220 billion kilograms of goods pass through annually
- 1 sluice, 16 meters wide and 135 meters long, for recreational boating, with a fixed bridge
Origin
The Volkerakdam was built to support the Haringvlietdam, Brouwersdam, and the Eastern Scheldt Barrier. It is a ‘secondary dam,’ protecting the southern part of Zeeland from high water, but not serving as the primary line of defense against the sea.
The economic function of the Volkerakdam, or more precisely the Volkeraksluizen, may be even more significant. The dam is located on an important shipping route between the two largest ports in Europe: Rotterdam and Antwerp. The sluices on this Schelde-Rhine connection are in use day and night.
Construction
In 1957, the construction of the Volkerakdam began with the process of sand dredging on the sandbanks that stretched from Goeree-Overflakkee to the present-day Hellegatsplein. The western part of the Volkerak was then closed off with twelve sluice caissons. These sluice caissons were heavy, hollow foundation structures (caissons) that allowed water to pass through during installation, preventing them from being carried away by the current. They had also been successfully used in the construction of the Veerse Gatdam. By 1969, the task was completed.
To the east of this section of the dam, a sluice complex was built in a (outer) polder to the west of Willemstad, with a total length of 4 kilometers, including the foreharbors. The complex featured two large sluice chambers, each 330 meters long and 24 meters wide, with a division in the middle. These two compartments help improve the flow of shipping traffic. The sluices were completed in 1967. Due to the growth of both commercial and recreational shipping, a third sluice chamber and a separate lock for pleasure yachts were added in 1977.
A lot of attention was given to integrating the Volkerakdam into the landscape during its design. After the closure, Staatsbosbeheer planted vegetation on the newly exposed lands, and later, nature was allowed to take its course.
The bridge from Hellegatsplein to the Hoeksche Waard is officially not part of the Delta Works and was built as a separate project. However, it was one of the reasons the dam was constructed in this particular way, with a dam leading to Hellegatsplein. This made the distance that needed to be "bridged" shorter. Hellegatsplein has become a traffic hub on the water, serving as a connection between Goeree-Overflakkee, Hoeksche Waard, and the mainland of North Brabant.
Functioning
The likelihood of the Volkeraksluizen being used to discharge water to prevent flooding is small. This only happens if the Maeslantkering and Hartel Barrier are also closed. In that case, during high water, the sluices of the Volkerakdam are opened to discharge water into the Volkerak-Zoommeer, which is surrounded by dikes.
In addition to its protective and economic functions, the Volkerakdam also serves a water management function. After the construction of the Philipsdam in 1987, it became possible to control the amount of freshwater in the Volkerak and the Zoommeer, the waters south of the dam, using the Volkerakdam. Freshwater from the Hollandsch Diep is directed towards these waters via the sluices. This helps reduce the growth of algae, which cloud the water and are harmful to the aquatic plants and animals. Additionally, the sluices are opened a few times a year to discharge salty groundwater, preventing salinization of agricultural land, for example.
