Storm surge barriers

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 rijkswaterstaat.nl and i-storm.org.