Dikes and Polders

As you travel around the Netherlands, you see windmills in surprising places. Some used to power industries, but many pumped water out of low lying areas surrounded by dikes to create polders. Remember that half of the Netherlands used to be marshes or sea. You see these polders everywhere. Most look like a series of rectangular fields surrounded by drainage ditches with a shallow drainage ditch in the middle. The windmills pump the water from lower ditches to increasingly higher canals and storage lakes until they can be pumped into rivers or lakes that are at sea level that can be opened to the sea to empty when the tide is low.


To see how this works we first took the train to the North Sea fishing town of Harlingen Haven. You can see how the dikes protect the town from the sea when there are high tides and storms.




Notice how the harbour can be closed off by large gates in the dike when the water level of the sea is too high. Nearby is the giant dike that closed off the Zuider Zee in 1932 to create the sweet water Ijsselmeer.

Here are some of the beautiful old buildings that are protected from flooding.



Later we took another train to Lelystad, the capital of Flevoland, the new province which lies completely under sealevel on the new polders that were created when parts of the Ijsselmeer were diked off and drained. Here you can see the dike that divides the old Zuider Zee into the Ijsselmeer and the lower Markermeer that Amsterdam lies on. It is lower to protect Amsterdam from flooding. Notice the giant gates they can open when the water on the Amsterdam side is too high because of increased flow from the rivers flowing into the Netherlands in the spring or from increased pumping from the polders. (They use diesel pumps now rather than windmills). This way they can quickly change the level of the lakes as the water flows uphill from canal to canal and lake to lake to the ocean. You can also see the sluices that the barges and ocean going ships coming from Amsterdam pass through as they go from this lower Markermeer to the higher Ijsselmeer. The dike also has a highway on top.



Here too is a picture of the stonework protecting the side of the dikes. The grassy meadow with a canal flowing through it is in an area that has recently been drained.(Sorry that the train window was so dirty.) It takes about 5 years for a polder to dry out enough so they can use it. They plant grass and trees to help the process. In this area there are now large herds of deer, bison, and wild cattle.


This large polder was opened for settlement in 1968 so everything is new with modern architecture. The Lelystad city hall pictured here is 18 feet below sea level. It is at most one mile inland from the dike you saw with the ship passing through.