Zuiderzeewerke

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Overview map of the Zuiderzeewerke

The Zuiderzeewerke ( Dutch Zuiderzeewerken ) are a large-scale system of dykes , reclamation areas and water pumping systems in the Netherlands . The aim was to separate the shallow Zuiderzee from the North Sea and to reclaim new land by building polders in the newly created IJsselmeer . In addition, flood protection should be improved and the arable land should be expanded. Along with the Delta Works , the Zuiderzee Works were selected as one of the Seven Wonders of the Modern World by the American Society of Civil Engineers .

overview

The plans for the Zuiderzee Works go back to the 17th century. As early as 1667, the Dutch engineer Hendric Stevin, a son of Simon Stevin , presented the plan to connect the West Frisian Islands with each other and with the mainland by means of dams so that large parts of the cordoned off area could be polded. However, this project could not be implemented with the technical means available at the time. It was not until 1916, after a flood disaster in the Zuiderzee, that official planning began on the basis of drafts by the engineer Cornelis Lely , who had become Minister of Transport in 1913.

The largest single object planned was the 32-kilometer-long closure dike (Afsluitdijk) , which should serve as protection from the North Sea . But first the Amsteldiepdijk was built for test purposes ; The construction time was four years and the knowledge gained was incorporated into the construction of the Afsluitdijk. When this was completed in 1932, the Zuiderzee was completely separated and renamed the IJsselmeer .

The next step after separation from the sea was the creation of new land called polder. This was achieved by building dykes in individual sections of the IJsselmeer and by pumping out the water. The first polder, the Wieringermeer , was diked in 1929 and was completely pumped out in 1930. The next polder, the Noordoostpolder , was completely emptied by 1942 and played an important role as a retreat for the Dutch resistance movement during the Second World War .

After the war the pumping out of the eastern and southern Flevoland began , an extensive project with an area of ​​over 1000 km². Today the cities of Almere and Lelystad are located there . Due to its proximity to Amsterdam , Almere is the fastest growing city in the country. In Markermeer another big polder was planned. It is uncertain whether it will ever be built, as the area has meanwhile acquired great ecological importance and has developed into a local recreation area. In 1986 the new province of Flevoland emerged from the Northeast Polder and the Flevolandpolder.

The Zuiderzeewerke was added to the list of Historic Civil Engineering Landmarks by the American Society of Civil Engineers in 1986 .

Planning phase and preliminary work

The first concept for the separation and drainage of the Zuiderzee had already been worked out in the 17th century, but failed due to the lack of technical possibilities. The first feasible plans appeared in the second half of the 19th century. The main concern was the protection from the open sea and the reclamation of valuable agricultural land. One of the most ardent advocates was the engineer and future minister Cornelis Lely. The project he worked out in 1891 served as the basis for the later Zuiderzee Works. It provided for a large dam between Noord-Holland and Friesland as well as the construction of four polders. The polders should arise in the north-west, north-east, south-east and south-west of the later IJsselmeer. In between there should be two waterways for shipping and drainage. The area affected by the original project was 3500 km².

Resistance came mainly from the fishermen who lived on the Zuiderzee and saw their livelihoods threatened. The residents of the Wadden Sea, on the other hand, feared an increased water level as a result of the separation of the Zuiderzee. Furthermore, doubts were expressed as to whether the project could be financed at all. When Lely became Minister of Transport and Public Works in 1913, the government officially began planning. After a winter storm in 1916, the dykes broke at various points on the Zuiderzee under the pressure of the water and the land behind them was flooded, as so often in previous centuries. This event, as well as the food shortage during the First World War, caused popular approval to rise.

On June 14, 1918, Parliament passed the Zuiderzee Act. The following goals were set:

  • Protecting the central Netherlands from the tides and the dangers of the North Sea,
  • Increase in Dutch food production through new agricultural land,
  • Better control of the water by converting the untamed saltwater bay into a freshwater lake.

In May 1919 the service of the Zuiderzeewerken was created; this authority supervised the execution of the project. It was decided not to build the main dam for the time being and instead build a smaller dam for test purposes. This was the Amsteldiepdijk across the Amsteldiep between the island of Wieringen and the North Holland mainland. Despite its shortness of only 2.5 kilometers, it took four years to complete (1920 to 1924). Valuable knowledge was gained, which flowed into the following stages of the project.

The Zuiderzee becomes the IJsselmeer

The 32 km long Afsluitdijk separates the IJsselmeer (right) from the North Sea (left)

When concerns about the financial viability of the project were raised, the government commissioned a study in 1927. This came to the conclusion that the work should not only be continued but even accelerated. In the same year it was decided to start immediately with the next two sub-projects. The first was the construction of the Afsluitdijk (Afsluitdijk) between Den Oever in Noord-Holland and Zurich in Friesland . Its length should be 32 kilometers, the width 90 meters, the initial height 7.25 meters above sea level and the side slope 25 percent.

Previous experiments had shown that boulder clay was far more suitable than sand or clay for the construction of such a structure. This clay was also readily available because it could be excavated on site at the bottom of the Zuiderzee with dredgers . Work began at four different locations at the same time, on both sides of the mainland and on the two artificially created construction islands Kornwerderzand and Breezand.

In the middle of the open sea, ships dumped the boulder clay in two parallel lanes, the space in between was then filled with sand until it reached sea level. A layer of boulder clay was laid on top of this. The foundation was eventually reinforced with basalt stones and mats made of willow rods . A layer of sand was placed on top of the clay layer, and over it a layer of clay on which grass was sown.

The construction progress was faster than expected. There were three sea trenches at three points along the dam where the tidal current was much stronger than elsewhere. It was assumed that the current would be a significant obstacle. But the problem had been overestimated and the work could be carried out without major complications. On May 28, 1932, two years earlier than originally planned, the last gap was closed with a ceremonial bucket of clay. The Zuiderzee had now become the IJsselmeer , even if it was still salty at the time.

The dike itself, however, was not yet completely finished as it still had to be brought to its final height; In addition, the road between Friesland and North Holland was still missing. The final dike was officially opened on September 25, 1933; at the point where the last gap was closed there is now a monument. A total of 23 million cubic meters of sand and 13.5 million cubic meters of boulder clay had been moved. On average, 4,000 to 5,000 workers had built the dam every day. During the global economic crisis , J. Th. Westhoff, the director of the state employment agency ( Rijksdienst voor de Werkverruiming ), made sure that the unemployed were included in the Zuiderzee program and in the expansion of the polders. This enabled the high unemployment rate to be reduced. The construction costs amounted to around 580 million euros based on today's value .

In addition to the actual dam, a complex with locks and sewer structures had to be built at both ends . The complex at Den Oever is called Stevinsluizen and includes a lock with three sluice systems, each with five sluices, through which the water of the IJsselmeer pours into the Wadden Sea . The second complex at Kornwerderzand is called Lorentzsluizen and has two locks for shipping and two sluice systems with five sluices each.

The polders

Overview of the dikes of the Zuiderzeewerke
Project length start of building Dike closure Pumped empty on
Amsteldiepdijk 2.5 km June 29, 1920 July 31, 1924 -
Afsluitdijk 32 km January 1927 May 23, 1932 -
Wieringermeer 18 km 1927 July 27, 1929 August 31, 1930
Noordoostpolder 55 km 1936 December 13, 1940 December 9, 1942
Oostelijk Flevoland 90 km Early 1950 September 13, 1956 June 29, 1957
Zuidelijk Flevoland 70 km Early 1959 October 25, 1967 May 29, 1968
Houtribdijk 28 km 1963 4th September 1975 -

Wieringermeer

Landsat photo of the IJsselmeer and surrounding areas; note the difference between the old country (mostly green) and the new country (mostly purple)

The second sub-project, which was tackled in 1927, was the construction of the 200 km² large polder in the northwest, the first and at the same time the smallest of the five planned polders. As a result, the water area known as the Wieringermeer was to be drained south of the island of Wieringen . The Wieringermeer polder was the only one that was wrested directly from the Zuiderzee (the other polders were only created after the final dike was completed). Between 1926 and 1927, a 0.4 km² test polder near Andijk in North Holland was built to investigate how the pumping out would affect the seabed and how the other polders should be built.

From the beginning, it was expected that the construction of the 18-kilometer-long dike in the Wieringermeer would be more difficult than the subsequent polders, as the final dike was not yet completed and the tides were still there. The construction of the dike and the construction island Oude Zeug went smoothly, so that the Wieringermeer could be separated from the Zuiderzee in July 1929. The next step was pumping out the water from the future polder.

Two pumping stations (Dutch: gemaal ) were built to empty the polder , the Leemans station at Den Oever , which is equipped with a diesel engine, and the electrically powered Lely station at Medemblik . The two different types of drive served as a mutual safeguard: If one station should fail due to a defect, the other would still be able to keep the polder dry. The stations completed in February 1930 were able to empty the polder within six months. “Pumping out” in this context does not mean that the land was completely dry; Scattered throughout the muddy polder were still numerous shallow still waters . To make the earth usable, a network of drainage ditches first had to be built. The main collecting canals that carried the remaining water to the pumping stations had already been dug when the polder was still under water. The drying up of the former seabed caused it to sink (up to a meter in some places). As soon as the ground settled, the smaller trenches were replaced by underground drainage pipes.

After the hydrological infrastructure was put into operation , the newly reclaimed land was prepared for later cultivation. The first plants to conquer the new habitat were reeds . The seeds were sown from planes that flew over the muddy polder when it was still being drained. These resilient plants soaked up the remaining water and enriched the soil with oxygen. This solidified the soil structure and prevented the spread of weeds.

The reeds were then burned and replaced with rape , which turned the polder into a sea of ​​yellow flowers in spring. Various types of grain then followed the rape. In the Wieringermeer this was initially rye ; In the following polders, however, wheat was sown first , then barley and finally oats . This process took several years at a time, but once it was finished the farmers could grow crops at their own discretion. At the same time, the infrastructure such as roads and residential buildings was built so that the polder could be settled. The Wieringermeer served as a huge testing ground for ideas and techniques that were to be applied in the subsequent polders. Even today the polder is used almost exclusively for agriculture ; it has a distinctly rural character and comes closest to the original concept.

Four villages emerged in the polder: Slootdorp (1931), Middenmeer (1933), Wieringerwerf (1936) and Kreileroord (1957). The local administration turned out to be complicated at first: the area was divided among the mainland communities according to the boundaries that existed when the Wieringermeer was actually still a sea. This arrangement turned out to be impractical as it only unnecessarily divided responsibilities. The first solution was the creation of a public body (openbaar lichaam) , which included both the state polder development company and a commission made up of representatives from the neighboring communities. As the population of the polder increased, this structure proved to be too complicated. After the new residents also called for a uniform administration, the municipality of Wieringermeer was finally founded on July 1, 1941 .

The great work was almost wiped out at the end of the Second World War . On April 17, 1945, a German commander ordered the dike to be blown up. While no one was killed as the water slowly rose again, the water that entered and a subsequent storm destroyed most of the infrastructure that had been built in the previous decade. However, the reconstruction took place quickly and by the end of 1945 the polder was drained again. This was followed by the reconstruction of roads, bridges, houses and farms.

Noordoostpolder

Satellite photo of the Northeast Pole

The original plan from 1891 planned to build the largest polder in the southeast just after the Wieringermeer. But in 1932 it was decided to prefer the smaller (and easier to build) Noordoostpolder . Financing problems meant that work did not begin until 1936. In IJsselmeer two dikes were built with a length of 55 kilometers together. One started at Lemmer in the province of Friesland , the other at Vollenhove in the province of Overijssel . Both dykes met at the island of Urk . The outbreak of World War II meant that the completion of the second dike and the construction of the pumping stations had to be postponed. The work could not be completed until December 1940 and the pumping stations did not start operating until the beginning of 1941. In September 1942, the 480 km² Noordoostpolder was drained so far that the development of the area could begin. The partly impassable terrain served the Dutch resistance movement as an ideal retreat.

The construction of the north-east polder was made easier by the experience gained, the tamed IJsselmeer and the mechanization of the construction processes. Specially built machines were increasingly used. As in the Wieringermeer , the focus of land use was on agriculture, areas with less fertile soil were planted with forests. During the development phase, the land belonged to the state, but a few years after completion, private individuals were also able to acquire property. First of all, the pioneers who had lived in the polder from the start were taken into account. Later, farmers from the rest of the Netherlands were also allowed to buy land; this after they had been subjected to a selection process.

Within the polder there are two former islands, the moraine hill of Urk and an elongated raised moor area called Schokland . Urk was and is still a community dominated by fishing . It served as a natural construction island during the construction of the dykes and was the operational basis for the later development of the polder. Urk was an island until October 3, 1939, when the north of the two levees was closed. The island of Schokland only disappeared in 1942 when the polder was pumped dry. Urk has remained independent to this day and is not part of the Noordoostpolder municipality , which was established in 1962 and comprises the rest of the polder.

The spatial planning structure of the Noordoostpolder was planned by Walter Christaller based on the system of central locations . The town of Emmeloord , founded in 1943, was created as a middle center in the middle of the polder . It is the administrative seat and the economic center of the municipality of Noordoostpolder. Around them, five farming settlements were planned as sub-centers, as well as another five more, as a population prognosis determined that these would not be enough. They were created at a distance that is easy to cover by bike. The first settlements were Ens, Marknesse and Kraggenburg (1949), followed by Bant (1951), then by Creil and Rutten (1953) and finally by Espel, Tollebeek and Nagele (1956).

From Emmeloord, three main drainage channels lead to the three pumping stations, the Buma station at Lemmer , the Smeenge station at Vollenhove and the Vissering station at Urk . The first two are electrically powered (but connected to two different power plants), while the third has a diesel engine. Like all pumping stations at the Zuiderzeewerke, they are named after people who made a significant contribution to the project.

Eastern Flevoland

The time after the Second World War was marked by the restoration of the Wieringermeer polder and the completion of the Noordoost polder. However, attention soon turned to the next sub-project, the eastern part of Flevoland (Oostelijk Flevoland) , which is the largest polder with an area of ​​540 km².

Work began in 1950 on several construction islands in the IJsselmeer, the largest of which was Lelystad-Haven, which served as a settlement for the construction workers. During the construction of the north-east polder it became apparent that the groundwater flowed from the old land into the new land, which resulted in the subsidence and drying out of the old land. Therefore, those responsible decided to hydrogeologically separate the polder from the mainland. For this purpose, a number of peripheral lakes were created ( Gooimeer , Ketelmeer , Veluwemeer ), so that the dike reached a length of over 90 kilometers.

Over time, the plans to build a single polder in the south-east were abandoned; instead, two separate polders were planned, but which should use the same hydrological infrastructure. In the middle, the Knardijk was intended as a protection for one of the polders in the event that the other should be flooded. In such an incident, the two main drainage channels could be closed with a weir .

Construction was going according to plan until February 1953 when a great flood inundated the southwest of the Netherlands (this event led to the construction of the Delta Works ). Workers and machines were withdrawn to be used in repairs. In 1954, work in eastern Flevoland was resumed and the dike was completed on September 13, 1956. On the same day, the pumping stations started running and had pumped the polder empty by June 1957. Three pumping stations had been built, the diesel -powered Wortman station in Lelystad-Haven and the electrically powered Lovink stations near Harderwijk and Colijn at the northern end of the Ketelmeer. All three had additional capacities, as they should also be used for the southern polder.

Lelystad harbor

The new polder was also designed according to the principle of central locations. A new element in the construction of this polder was therefore the intention to build a larger city that would act as a regional center for the other polders and later perhaps be the capital of a future province in order to continue the decentralization policy of the then government. This town in the middle of the newly won land was Lelystad , founded in 1966 , named after Cornelis Lely , the initiator of the Zuiderzeewerke. At this point in time there were already some smaller settlements: Dronten as a middle center was founded in 1962, followed by the smaller satellite villages Swifterbant and Biddinghuizen in 1963. On January 1, 1972, the municipality of Dronten was formed from these settlements . Lelystad was officially founded on January 1, 1980.

Originally, the plans had provided that this polder should also be mainly used by agriculture. However, the falling demand for agricultural land, greater mobility and the overly high population growth meant that the number of planned farming settlements had to be further reduced. If the number of locations had already been reduced to five after it was recognized that too many had been created on the Noordoostpolder due to the forecast, it now had to be reduced to just two. Construction of the Larsen settlement was stopped shortly before construction began; the fifth, named Zeewolde , experienced a renaissance on the "Südliches Flevoland" polder. The proportion of forests and nature reserves was also much higher, since they no longer just covered the less fertile land.

Southern Flevoland

The fourth polder, the southern Flevoland (Zuidelijk Flevoland) , was created immediately next to the eastern half. Since the Knardijk already existed in the northeast, only dykes with a length of 70 kilometers had to be built. Work began at the beginning of 1959 and was completed in October 1967. Since the two halves of Flevoland formed a hydrological unit, only one pumping station had to be built, the diesel- powered De Blocq van Kuffeler station . it pumped the 430 km² polder empty by May 1968 on its own. It was then operationally connected to the three other stations and has since kept the water level under control together with them.

Due to the favorable geographical location near the densely populated Randstad and Amsterdam in particular , those responsible planned a large city called Almere to alleviate the housing shortage and reduce overpopulation in the central Netherlands. The city consists of three large settlements separated by green belts: Almere-Haven along the Goimeers (1976), Almere-Stad (1980) in the center and Almere-Buiten (1984) in the northeast towards Lelystad.

An area between Almere and Lelystad was originally intended for heavy industry. But since there was still enough space on the mainland for this purpose, this zone was largely left to its own devices. Within a few years, the so-called Oostvaardersplassen turned into a breeding and hunting area for water birds and finally into a nature reserve of national importance.

The central part of the polder is most similar to the pre-war polders as it is almost exclusively used for agriculture. In contrast, the southeastern part is covered by a dense forest. The only other settlement in the polder is located there, Zeewolde , which was built in 1984 . Together with Almere, Zeewolde was raised to the status of a municipality on January 1, 1984, at a time when the settlement was not yet completed.

Land use on the existing polders

The following table shows the size and distribution of the types of use of the existing polders.

Land use of the polders
(in% of the total area)
Polders size Agriculture residential area nature Infrastructure
Wieringermeer 200 km² 87% 1 % 3% 9%
Noordoostpolder 480 km² 87% 1 % 5% 7%
Oostelijk Flevoland 540 km² 75% 8th % 11% 6%
Zuidelijk Flevoland 430 km² 50% 25% 18% 7%

Markerwaard

Map with the planned Markerwaard polder

The fifth polder does not yet exist and may not be completed. The construction of the 410 km² south-western polder, also known as the Markerwaard, had been postponed several times in favor of other projects. Parts of it were built anyway. In 1941 the government decided to start the first section of the dike. This 5 km long and 30 meter wide dike, the Bukdijk (German meaning: "Bückdeich"), extends from Marken to the north, the last remaining island in the IJsselmeer, and ends after 2.5 kilometers. Although other polders had priority, Markerwaard was never completely lost sight of. On October 17, 1957, a 3.5 kilometer long dike was completed between the island and the mainland.

When the construction of a third dike began in 1959, it was not yet certain whether it would be the northern dike of South Flevoland or the southern dike of Markerwaard. But then the choice fell on the first variant and another opportunity for Markerwaard was missed. In 1960 a minor flood near Amsterdam demonstrated the danger the IJsselmeer still posed. As a result, another element of Markerwaard was built, a 28-kilometer dam between Lelystad and Enkhuizen , including two complexes with shipping locks and drainage channels at both ends. As a result, the IJsselmeer shrank to an area of ​​1250 km², in return the 700 km² Markermeer was created . The construction of this dam, later known as Houtribdijk or “Markerwaarddijk”, took over twelve years, from 1963 to 1975. Since its completion, the dam has served as an important road link between Noord-Holland , Flevoland and Gelderland .

The debate about whether the Markerwaardpolder should be finished at all dragged on for over a decade. There was no longer any need for additional agricultural areas, and no new housing developments were necessary in this region. The ecology and the value as a local recreation area were increasingly weighted higher than the possible advantages of the polder. There were also doubts about the cost-benefit ratio. Although several governments had announced that they would continue to build the Markerwaardpolders, also as a possible location for a major airport (as an alternative to the expansion of Amsterdam Airport Schiphol), it was decided in 1986 to postpone the project indefinitely. In 2003 the project was finally abandoned.

Despite the lack of the Markerwaardpolders, the plan to create a new province from the land that had been won was stuck to. This should simplify administration; for the individual communities were in different provinces. Urk and the Noordoostpolder were part of the Overijssel province , while Dronten was part of Gelderland . Lelystad and southern Flevoland were even provincial-free areas. Finally, on January 1, 1986, Flevoland and the Northeast Polder were united to form the province of Flevoland , with Lelystad as the capital. The Wieringermeer was not one of them and remained with the province of Noord-Holland . Since 1996, the “ Rijkswaterstaat IJsselmeergebied” subordinate to the Ministry of Transport has been responsible for maintaining the infrastructure.

See also

literature

  • Directie van de Wieringermeer (Ijsselmeerpolders) (Ed.): Oostelijk Flevoland , self-published 1961
  • NV Handelsdrukkerij Holdert & Co. (Ed.), Departement van Waterstaat, Directie der Zuiderzeewerken: De Afsluiting en Gedeeltelyke Droogmaking van de Zuiderzee , NV Handelsdrukkerij Holdert & Co., Amsterdam (documentary series published annually from 1929 until the end of the project)
  • Willem van der Ham: Heersen en Beheersen - Rijkswaterstaat in de twingste eeuw , Europese Bibliotheek, Zaltbommel 1999.

Web links

swell

  1. Horst Lademacher : History of the Netherlands. Politics - Constitution - Economy . Scientific Book Society, Darmstadt 1983. ISBN 3-534-07082-8 . P. 348.
  2. Harald Bathelt and Johannes Glückler: Wirtschaftsgeographie , UTB Ulmer, Stuttgart 2003, p. 118
This version was added to the list of articles worth reading on June 12, 2005 .