In 1953 major flooding took place in South Holland when a tidal wave broke through dikes flooding the islands of the region killing 2000 people and running vast amounts of agricultural land.
To prevent another event of this magnitude happening again the Dutch government launched the ‘Delta Project’. As a result of this project The Ooster schelldedam was built between 1976 and 1986. The dam itself is 3 km in length with 62 flood gates in between piers 38m high. The gates only close when the sea becomes dangerous meaning disturbance to industry and surrounding national parks is kept to a minimum.
Following the building of this flood barrier, the construction of a storm surge barrier, on the Nieuwe Waterweg, near the major port of Rotterdam, began in 1991. This barrier was constructed so it would cause the least amount of disturbance to shipping in and out of the port and it was predicted that the barrier would only close on average twice every ten years.
The Maeslant barrier was finally completed in 1997 consisting of 2 gates each 210m long. These gates reside in docks lying along the banks of the waterway and during storm surges, these docks are flooded allowing the hollow gates to float. A little ‘locomotive’ then enables them to move into the middle of the waterway, taking less than half an hour. Once the gates meet, valves in there walls are flooded and the cavities fill with water, sinking them to the concrete sill on the channel bed. The joints on the gates are ball and socket type, allowing free range of movement. The joints are 10m in diameter and weight 680 tonnes each.
The Maeslant barrier is controlled by a computer, with a decision and support system known in Dutch as the Beslis & Ondersteunend Systeem. The computer calculates the expected water levels in Rotterdam and surrounding areas on the basis of water and weather forecasts.