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 weirs 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 )
North Sea flood of 1953
North Sea flood of 1953
Zuiderzee Works