Delta Works, Netherland

The Delta Works are a number of constructions that were built between 1950 and 1997 in the southwest of the Netherlands to protect a large area of land from the sea. The works consist of dams, sluices, locks, dikes and storm surge barriers. The aim of the dams, sluices and storm surge barriers was to shorten the Dutch coastline and limit the amount of dikes that were to be heightened.
History

The estuaries of the rivers Rhine, Meuse and Scheldt have been subject to many floodings over the centuries. After building the Afsluitdijk, the Dutch started studying the damming of the Rhine-Meuse Delta. Plans were developed for shortening the coastline and turning the estuary into freshwater lakes. By shortening the coastline less dikes would have to be reinforced.

Due to indecision and the Second World War, these plans remained studies and little action was taken. In 1950 two small estuary mouths, the Brielse Gat near Brielle and the Botlek near Vlaardingen were dammed. After the North Sea flood of 1953, a commission was installed which had to come up with a plan to research the causes and seek measures to prevent such disasters in future. They revised some of the old plans and came up with the so called "Deltaplan".

[edit] Lay-out of the plan

The plan consisted of blocking the estuary-mouths of the Oosterschelde, the Haringvliet and the Grevelingen. This reduced the amount of dykes exposed to the sea by approximately 400 miles. The estuary-mouths of the Nieuwe Waterweg and the Westerschelde were to remain open because of the shipping routes to the ports of Rotterdam and Antwerp. The dikes along these waterways were to be heightened and strengthened. The works would be combined with road and waterway infrastructure to stimulate the economy of the province of Zeeland and improve the connection between the port of Rotterdam and Antwerp.

[edit] Alterations to the plan during the execution of the Works

During the execution of the works alterations were made due to pressure from society. In the Nieuwe Waterweg heightening and the associated widening of the dikes proved very difficult because of many historic buildings standing in the way. Therefore a storm surge barrier would be built (the Maeslantkering) and dikes were only partly heightened.
Oosterscheldekering, the largest of 13 Delta Works' dams.
Oosterscheldekering, the largest of 13 Delta Works' dams.

The Oosterschelde was originally to be dammed and turned into a fresh water lake. The saltwater nature and the fishing of oysters would have then been lost. Environmentalists and fishermen combined their efforts to stop this and successfully pressed parliament to make amendments to the original plan. Instead of completely damming the estuary mouth, a storm surge barrier would be built.

The storm surge barrier only closes when the sea-level is expected to rise above 3 meters above mean sea-level. Under normal conditions the estuary mouth is open and salt water flows in and out with the tide. Consequently, the weak dikes along the Oosterschelde needed to be strengthened. This strengthening had not been done yet because the Oosterschelde would be dammed. Over 200 km of dike needed new revetments. The connections between the Eastern Scheldt and the neighboring Haringvliet had to be dammed to limit the effect of the salt water. Extra dams and locks were needed at the east part of the Oosterschelde to create a shipping route between the ports of Rotterdam and Antwerp.