Protection against water

Protection against water

A large part of our country lies below sea level; that makes us vulnerable to flooding. Protection against flooding will always remain vitally important.

Rijkswaterstaat monitors water levels along the coast, in rivers and in lakes. We issue early warnings of a threat of storms and high water levels, so that water authorities can take action before there is any real danger. If necessary, we close the storm surge barriers.

Storm surge barriers protect the Netherlands against flood

Rijkswaterstaat manages and maintains five storm surge barriers: the Oosterschelde barrier, Maeslant barrier, Hollandsche IJssel barrier, Hartel barrier and Ramspol storm surge barrier. Storm surge barriers are imposing, moveable flood barriers to protect the country from flooding. This animation shows how the barriers work.

The Netherlands is a land of water. A large part of our country lies below sea level and many large rivers make their way through it to the ocean. This makes the Netherlands vulnerable to flooding. What's more, the sea is rising, the land is subsiding and violent storms, heavy rain and high water levels are becoming increasingly more common. Water protection is thus of vital importance, to millions of Dutch citizens and the Dutch economy. To protect the Netherlands against floods, our country has more than 3,700 kilometres of water defences. These include not only natural defences, such as sand dunes, but also man-made defences, such as dykes, dams and storm surge barriers. Without these defences, large areas of the Netherlands would flood. Storms pose a major flood threat to the coastal areas and around the large lakes, as they can force water to build up, leading to much higher water levels. The Water Management Centre the Netherlands, which forms part of the Directorate-General for Public Works and Water Management (Rijkswaterstaat), monitors the weather around the clock to determine whether and when storms can occur. And we alert water managers well in advance so that they can take measures to prevent flooding. We use colour codes to indicate the anticipated water levels. Green indicates that no special circumstances are expected, while red indicates a serious, exceptional situation. When water is expected to reach a certain level, we close the defences. All water defences work according to the same principle: if the water rises too much, the defence is closed. When the water has returned to its normal level, the defence is reopened. Rijkswaterstaat manages the storm surge barriers. These barriers are enormous, moveable defences that are built to protect against high water levels. The water levels behind the barriers remain lower, meaning that the dykes behind them do not have to be as high.ÊWe manage five storm surge barriers: the Hollandsche IJssel barrier, the Eastern Scheldt barrier, the Hartel barrier, the Maeslant barrier and the Ramspol barrier. All of these barriers are technically ingenious structures that close in different ways. One storm surge, the Kromme Nol, is managed by the water board (River Land), aÊregional water authority. The Eastern Scheldt barrier, for example, has sluices which Ð at the push of a button Ð can be closed to protect against high water. The Maeslant barrier has dry docks that can be filled with water in the event of a storm. This causes the barrier's two hollow doors to float, allowing them to rotate closed across the Nieuwe Waterweg canal. When the doors meet, they fill with water and sink to the bottom. The Ramspol barrier is an inflatable rubber dam with three sections Ð essentially giant balloons Ð which, when closed, can be pumped with air and water. Rijkswaterstaat inspects and maintains these storm surge barriers, ensuring that they continue to meet the statutory safety requirements. This how we work together with the water boards, provinces and municipalities to protect the Netherlands against storms and floods, both now and in the future. If you would like to find out more, please visit and

Flood defences

Dykes, locks, dams and other flood defences repel the water and protect our country against floods. The best-known flood defences are the 13 Delta Works, which make up the country’s largest coastal flood defence system.

  • The Oosterschelde storm surge barrier is the largest and most famous of the Delta Works. The nine-kilometre long barrier seals off the Oosterschelde when there is a threat of flooding.

  • No flood barrier in the world has larger moving parts than the Maeslant storm surge barrier. This Delta Work can withstand a flood wave of up to five metres above NAP.

  • The Hollandsche IJssel storm surge barrier protects the lowest-lying region of the Netherlands, which is 6.76 metres below NAP. This structure near Krimpen aan den IJssel was the first of the 13 Delta Works to be completed.

  • The Hartel storm surge barrier forms, together with the Maeslant barrier and the expanded Rozenburg dyke, the Europoort storm surge barrier. The barrier operates fully automatically.

  • The Brouwers dam offers protection against high water levels and powerful waves from the sea. The dam is the second-largest of the Delta Works after the Oosterschelde storm surge barrier.

  • The Grevelingen dam mitigates the current in the Grevelingen, the Haringvliet and the Volkerak, thus reducing the pressure on the Haringvliet dam, the Brouwers dam and the Oosterschelde storm surge barrier.

  • The Oyster dam is the longest dam in the Delta Works. It protects nature and shipping by separating the Oosterschelde from the Schelde-Rhine canal.

  • The Veerse Gat dam and the Zandkreek dam together seal off Lake Veer. The two dams protect the coast of Zeeland against assault from the sea.

  • The Zandkreek dam was the first Delta Work to be completed in Zeeland. Together with the Veerse Gat dam, it seals Lake Veer off from the sea.

  • The Philips dam separates the fresh-water Lake Volkerak-Zoom from the salt-water Oosterschelde. Ships can still pass through the dam thanks to its four Krammer locks.

  • The Haringvliet locks are situated between the North Sea and the mouth of the Haringvliet. They regulate the water level and are known as ‘Europe’s tap’.

  • The Volkerak locks constitute Europe’s largest and busiest inland shipping complex. They are of great economic importance for shipping.

  • The Bath Spui lock refreshes the water in the Zoom lake by discharging excess fresh water into the Westerschelde, thus improving the quality of the water.


The Netherlands has to dispose of a growing volume of water: it rains more often, the sea level is rising and rivers have to discharge more water. To protect the country, Rijkswaterstaat therefore adopts various measures to prevent flooding.

  • Rijkswaterstaat is undertaking measures to increase the capacity of rivers at 30 locations in the Netherlands in order to reduce the risk of flooding.

  • Rijkswaterstaat is engaged in projects to make the Meuse river safer and easier to navigate and to improve nature along 222 kilometres of the river.

  • The Delta Programme sets out the measures we can take to protect ourselves against flooding and guarantee an adequate supply of fresh water.

  • To the south of The Hague, we deposited 21.5 million m3 of sand to create the Sand Motor. The sand is now being distributed along the coast by the wind and the current.

  • Rijkswaterstaat carries out inspections of the water defences. We strengthen any barriers that are not robust enough according to the specifications in the Flood Protection Programme.