Delta Plan

Delta Plan

The Delta Committee, which was specifically set up for the development of the plan in 1953, presented the Delta Plan the same year. It is one of the most revolutionary hydraulic engineering projects in the world. A project with only one goal: to prevent a disaster like the one  in 1953 from ever happening again. One of the most important tasks is shortening the coastline by 700 kilometers. The motto being: “The shorter the coast, the easier the defense.”

In order to achieve this goal, the Delta Committee proposes to completely close off the estuaries in the delta area and to bring all sea defenses up to ‘Delta height’. The guiding principle  is a water level of five meters above NAP at the Hook of Holland. The Delta Committee calculates that by implementing these measures the probability of flooding occurring will be once every 4000 years in the delta area and the north, and once every 10,000 years in the Randstad (area in and around the four largest cities).

Water management

The Delta Plan not only offers safety but also provides better water management. As a result, the salinisation of agricultural land can be limited and there is potential for freshwater basins for farming. New recreation areas such as the Veerse Meer are being created by the Delta Works. Thanks to the Delta Plan dams, the islands of Zeeland and South Holland are far better accessible, resulting in an enormous boost to recreation and tourism. The Delta Works also give a major impetus to employment. For years, tens of thousands of people work on the Delta Works. For the Dutch hydraulic engineers, the Delta Plan is an enormous task. They cannot solely rely on experience and existing techniques. Therefore the choice is made to build from small to large and from easy to difficult.

Special machines

New technical developments can gradually be tried out and further developed. Prefabrication is in vogue and new special machines are being designed. In 1961, in addition to the normal caissons, permeable caissons are introduced. A cable car with a gondola is designed for closing off large areas.Plastics make their appearance in the early 1970s to be used in soil protection and dike cladding. Water flow  studies are becoming increasingly sophisticated through laboratory research. The computer becomes a common tool and measurement techniques and weather forecasts are becoming more and more accurate.First, the storm surge barrier in the Hollandsche IJssel (1954-1958) is built. This is followed by Zandkreekdam (1957-1960), Veerse Gatdam (1958-1961), Grevelingendam (1958-1965), Volkerakdam (1955-1977), Haringvlietdam (1956-1972) and the Brouwersdam (1963-1972).To increase the water levels  in the Oosterschelde for the benefit of oyster cultivation, the sea arm is divided into manageable compartments. This is done with compartmentalisation dams: Philipsdam (1967-1987), Oesterdam (1977-1988), Markiezaatskade (1980-1983) and Bathse Spuikanaal and Spuisluis (1980-1987).

Opening Stormvloedkering prinses Beatrix

Oosterschelde Open 

The construction of one of the most innovative parts of the Delta Works, the building of the storm surge barrier in the Oosterschelde, begins in 1967. After fierce protests by fishermen and conservationists – battle cry: Oosterschelde Open (OSO) – it is decided in 1974 to abandon the plan of completely closing off the sea arm. To preserve the tide in the Oosterschelde as much as possible, a barrier with 62 openings of 40 meters wide is chosen. When extremely high water levels are expected, these openings can be closed with heavy hydraulic slides to protect the hinterland.On October 4, 1986, the Oosterscheldekering (cost 2.5 billion Euro) is officially opened by then Queen Beatrix. At the same time, 140 kilometers of dike are strengthened further, after 135 kilometers of dike and 25 kilometers of dune have already been reinforced earlier. These dikes can withstand a super storm that only occurs once every five hundred years.