About the Afsluitdijk

The Afsluitdijk is an iconic Dutch dam and causeway connecting the northern provinces of Noord-Holland and Friesland and protecting the Netherlands against floods. The 32-kilometre dyke is part of the A7 motorway and literally shuts Lake IJsselmeer off from the sea.

The Afsluitdijk was constructed as a result of the flood of 1916. During this storm, dozens of people drowned in the Zuiderzee area, thousands of people lost their homes and the economic losses were huge. By that time, people had already been discussing the possible impoldering of the Zuiderzee for 25 years: Cornelis Lely – an engineer and later Minister of Water Management – had already had a plan prepared since 1891. After the storm surge, in 1918, he managed to get the Zuiderzee Law passed. Two years later, the Zuiderzee Works commenced, and on 28 May 1932 the last tidal trench in the Afsluitdijk was closed. The Zuiderzee was renamed IJsselmeer and the salt water slowly turned fresh. From 1933, the Afsluitdijk was opened to traffic.

The construction of the Afsluitdijk was one of the most important events in the 1930s. The dyke ended floods, produced land for food production and urban development and created a large freshwater basin for the drinking-water supply and other purposes. Besides, with this huge project the Netherlands could show the world what it was capable of.

Polygoon Nieuws  Nederland – Dichtmaken van het laatste gat in de Afsluitdijk.

With its 32 kilometres, the Afsluitdijk is the longest dyke in Europe. But actually the Afsluitdijk is not a dyke, but a dam. A dyke separates water from land and a dam separates two water bodies. The Afsluitdijk separates the Wadden Sea and Lake IJsselmeer, so officially it is a dam.

During a national safety test in 2006, it turned out the dyke no longer met the safety standards. One of the causes is climate change. Sea levels are rising and we increasingly face extreme weather. The dyke must be able to withstand a ‘superstorm’, a heavy storm that occurs once every ten thousand years. In 2006, the height of the dyke no longer served this purpose. Moreover, in case of serious flooding, the lining of the dyke could be washed away. If this resulted in a hole or crack in the dyke, the water level of the IJsselmeer would rise to such a level that the dykes behind it would burst.

In 2018, the Levvel consortium, consisting of BAM, Van Oord and Rebel, started the work commissioned by Rijkswaterstaat. The project is expected to be completed in 2025.

No, the New Afsluitdijk will be only two metres higher, at the Wadden Sea side. Here, the dyke will also have a new lining with specially designed Levvel-blocs. The blocs are so strong they will be able to withstand waves that hit the dyke in the event of a heavy storm. Moreover, the dyke is made burst-proof. This means it can process excess water without causing any damage.

The locks and drainage sluices are also made future-proof. The storm doors are replaced by flood barriers and to discharge excess water from Lake IJsselmeer to the Wadden Sea, two pumping stations with three pumps each will be installed. This is necessary because the locks can be opened less frequently due to the rising sea levels, while the volumes of water flowing via the IJssel to the IJsselmeer will increase in the future.

First of all, the renovation guarantees water safety. In addition, it creates jobs. And attracts tourists. Here is why: while the State ensures safety, the region seizes the opportunity and uses the overhaul to initiate projects on and around the dyke. The Afsluitdijk serves as a testing ground for sustainable energy projects; a fish migration river will be constructed and the locks at Kornwerderzand are widened, so bigger ships can sail onto the IJsselmeer. Tourist facilities like the Afsluitdijk Wadden Center, a new footpath and bicycle path along the Wadden Sea and the renewed monument should attract more tourists, for a longer time.

Contrary to 1932, when following the construction of the dyke the regional economy collapsed because all the labourers returned home, these projects ensure long-term employment.

Around the Afsluitdijk, sustainable energy is generated in various ways. On the IJsselmeer, by means of the new Windpark Fryslân. In addition, Rijkswaterstaat aims to make the dyke energy neutral; the dyke must yield as much as it uses. To neutralise the energy consumption of the pumps at Den Oever, as a final piece of the project, a solar farm will be installed.

The Afsluitdijk is also a testing ground for sustainable and innovative energy technology. On and around the dyke, various pilots were carried out, for example generating energy with running water. The testing ground flourished until the renovation activities took over all the space. Experiments like Solaroad, a concept which converts sunlight on the road surface into electricity, and an Off Grid Test Centre for managing sustainable energy were cancelled for various reasons. The Blue Energy Test Plant at Breezanddijk is still in use.

Before the construction of the Afsluitdijk , the Zuiderzee was an estuary, a link between the sea and the rivers. The rivers gradually merged into the sea, which resulted in a variety of habitats and great food productivity. It was an abundant fishing area with more than fifty species, a nursery for fish and an eldorado for birds.

After the creation of the Afsluitdijk, the water in Lake IJsselmeer became fresh within months. The dynamics in the area dwindled, the water level was strictly regulated and the causeway blocked the migration routes of millions of fish. Solid dykes and an unnatural water level management – low in winter and high in summer – created a situation with insufficient gradual transitions between land and water. It is precisely in these shallow grounds that fish spawn and birds find food.

When carrying out the Zuiderzee Works and the Delta Works, engineers assumed a sea-level rise of only forty centimetres. The current delta programme is based on a maximum rise of one metre by 2100. Besides, when designing weirs, engineers take into account a storm that may occur once every ten thousand years.

After the renovation, the Afsluitdijk will again comply with the safety standards until 2050. Whether the alterations will suffice is anybody’s guess. There is great uncertainty about the magnitude of the sea-level rise. Because it is hard to take measures if you do not exactly know what to expect, Rijkswaterstaat opts for ‘adaptive delta management’: looking ahead and adjusting things on the shorter term. Meanwhile, options are explored for more fundamental measures in case the future situation develops in a less favourable way. The current adaptation measures have been conceived in such a way that after 2050 the Afsluitdijk can easily be reinforced until the year 2100.

According to KNMI, a superstorm is an extreme storm that can occur once in ten thousand years. A storm that occurs during very exceptional circumstances when two storm depressions come together. This rare storm comes with extreme wind speeds, a lot of precipitation and spring tides that 'push' the seawater towards the coast and pose a danger to the dikes. The Afsluitdijk, just like other Dutch flood defences, is designed for such a once-in-a-lifetime storm. Because once in ten thousand years could theoretically be as soon as next month.

The government and the provinces bordering on the Afsluitdijk see the renovation as an opportunity to launch innovative projects involving delta technology, nature and energy.

For example, by using special concrete blocks, so-called Levvel blocs that were specially designed for the Afsluitdijk, 35 percent less concrete is used. The blocks are made from different innovative concrete mixtures. The Afsluitdijk acts as a testing ground; the blocks are extensively tested in extreme conditions. This way, the whole sector can learn from the results.

The Nieuwe Afsluitdijk execution plan is brimming with plans for innovative nature and energy projects. The fish migration river, the Blue Energy pilot plant and the Wadden Center have now been realised. Promising projects like a demo centre for tidal energy and an off-grid test centre to couple and store different renewable energy sources were cancelled.

The economic value of the widened lock is substantial. Both for shipyards in the IJsselmeer area and the many dedicated suppliers and for the hinterland, from Kampen to Meppel. An economic impact study from 2016 calculated an employment growth of three thousand jobs in the IJsselmeer area. Owing to the wider lock, dock industries and shipyards will have room to grow and have stated they will invest 110 million euros extra.

In the future, the widened lock at Kornwerderzand will offer space for the ever-wider coastal vessels that are built in Kampen, Urk and Lemmer. Moreover, cargo ships can directly sail from the Baltic region to the ports of Kampen and Lelystad. Goods will no longer have to be transported from and to Rotterdam first. This saves time and money and relieves the busy seaports and road transport.

The Afsluitdijk protects the cities and villages on the shores of the IJsselmeer and, further inland, Kampen and Zwolle. When the Afsluitdijk is breached, cities like Amsterdam and Almere are also jeopardised.

The Afsluitdijk belongs to the primary dams of the Netherlands, a dyke that protects the land against the open water. In prescribing the safety standards for the dams further inland, the authorities took into account the dampening effects of a primary dam. So, the dams around the IJsselmeer are relatively low owing to the proximity of the Afsluitdijk. Via the rivers, cities like Zwolle and Kampen are directly connected to the IJsselmeer, so they are in immediate danger if the Afsluitdijk is breached. Amsterdam and Almere are protected extra by the dams behind the Afsluitdijk, like the Houtribdijk, but this also takes the Afsluitdijk into account as the first line of defence against the water.

When the Afsluitdijk is breached, this will cause a catastrophe in many ways. First of all, in terms of safety, because a large part of the Northern Netherlands may be flooded. But also economically, because it would make Friesland less accessible. Finally, salt water will end up in the IJsselmeer, compromising the drinking water supply.