Delta Works

Difference the project has made

The South Holland coast region is home to approximately 4 million people who live below normal sea level. The loss of human life in a major flood here can be immense because there is typically with North Sea storms very little warning time.

Large scale evacuations aren’t a realistic option as there are so many people and the floods would spread so far over the flat landscape.

After a catastrophic North Sea flood in February 1953 which killed 1,835 people and devastated 2,070km² of land the Dutch government recognised the urgent need for a solution to flooding and coastal management.

The project ensured the protection of a huge area of land from salt water flooding and protected fresh water supplies for the region’s population. It also created many new roads and connecting bridges built over the dams and dikes, ending the historic isolation of some areas from the rest of the Netherlands and dramatically cutting journey times.

The project also contributed research to help solve the flooding problem. Instead of analysing past floods and building protection good enough to deal with those, the Delta Works commission pioneered a framework which could be used to calculate what future flood defences should look like to create a better protection for the country’s coastal areas. This framework is used by engineers all over the world today.

Although a number of nature reserves were lost, new nature reserves were created to replace them and the works have also created areas of recreational use such as the dry shores where locals and tourists walk, fish, ride horses and picnic.

How the work was done

The Dutch Department of Waterways and Public Works chose to complete the first set of works in a highly logical order, starting from the smallest and building towards the largest, and from the simplest to the most complicated. This way the engineers learned as much as possible during the construction process.

The largest of the Delta Works – the Oosterscheldedam – is a huge storm surge barrier and the biggest in the world. Its doors close only in extreme weather conditions. This means that the unique salt water environment where mussel and oyster cultivation is a traditional industry is protected and the tides stay the same for the conservation of the wildlife.

This mammoth construction is made up of 65 prefabricated concrete pillars with 62 steel slides in between. To strengthen the soil the barrier was placed on, gravel filled synthetic mats were used.