Editing Zuiderzee Works (section)

====Eastern Flevoland====
[[File:Flevopolder by Sentinel-2, 2018-06-30.jpg|alt=|thumb|Zuidelijk and Oostelijk Flevoland (Southern and Eastern Flevoland)]]
The period following World War II was spent restoring the Wieringermeerpolder and catching up with work on the Noordoostpolder. Soon attention turned towards the next project: Eastern Flevoland (Oostelijk Flevoland), which at 540&nbsp;km<sup>2</sup> was the largest of the new polders. In 1950 work commenced on several construction-islands in the middle of the IJsselmeer, the largest of which would be Lelystad-Haven, which initially housed a community of dike-builders.

The experience of the Noordoostpolder had shown that [[groundwater]] from the higher old mainland would flow to the lower new land, causing [[subsidence]] and dehydration in the old land. It was decided to use [[geohydrology]] to detach the new polders from the mainland. A string of peripheral lakes have been left between the two, requiring a much longer dike of {{cvt|90|km}} to encircle the polder.

The plans for a single south-eastern polder were changed to construct two separate polders with a joint hydrological infrastructure. They were divided by a dike in the middle, the ''Knardijk'', which would keep one polder safe should the other be flooded. The two main drainage canals to traverse the dike could be closed by [[weir]]s in such a flooding event. The eastern polder was planned to be the first, and the encircling dike began to take form in 1951. It progressed until the [[North Sea flood of 1953]] struck the south-western Netherlands. Workers and machinery were transferred there for repair work (additional work here was part of the [[Delta Works]]).

Work on Eastern Flevoland resumed in 1954 and the dike was closed on 13 September 1956. The pumping stations started draining the polder that same day, completing the task in June 1957. Three pumping stations were built: the ''[[H. Wortman Pumping Station|Wortman]]'' (diesel powered) at Lelystad-Haven, the ''[[H. J. Lovink Pumping Station|Lovink]]'' near [[Harderwijk]] and the ''Colijn'' (both electrically powered) along the northern dike beside the Ketelmeer. All three were built with extra capacity with the future southern polder in mind.

A new element in the design of this polder was the intention to establish a larger city to serve as a regional centre for all the polders and perhaps the capital of a potential new [[Provinces of the Netherlands|province]]. This city, located in the centre of the reclaimed lands, was developed as [[Lelystad]] (1966), named after the man who had played a crucial role in the design and realisation of the Zuiderzee Works. Other more conventional settlements had already developed by then; Dronten, the local major town, was founded in 1962, followed in 1963 by two smaller satellite villages, Swifterbant and Biddinghuizen. These last three were incorporated into the new municipality of [[Dronten]] on 1 January 1972. Lelystad was large enough to be organized as a separate municipality on 1 January 1980.

Though agriculture was initially the main purpose of the polder, needs of the post-war period changed the design goals of the new polders. Changing agricultural needs and increased motorised mobility meant many farming villages were unnecessary and the number of towns was eventually reduced to two. Work on the village of Larsen was just about to start when it was cancelled. The amount of agricultural land did not increase; it diminished as a result of the building of Lelystad (a city envisioned to eventually house at least 100,000 inhabitants.) By 2005 it had 70,000 residents. In addition, more area was assigned for development as forests and nature reserves, a trend that would continue in the next polder.