How the Dutch Keep Their Feet Dry: Dikes, Polders and the Delta Works

Water in numbers

Centuries of engineering

1. Middle Ages
   Dikes and the first water boards

   Farmers joined forces to build and maintain dikes, the start of the water boards.

2. 1600s
   Windmills drain lakes

   The Beemster (1612) was among the first large lakes pumped dry; it is now UNESCO World Heritage.

3. 1684
   NAP

   The Amsterdam water level became the reference for heights: Normaal Amsterdams Peil.

4. 1932
   The Afsluitdijk

   A 32 km dam closed off the Zuiderzee, which became the IJsselmeer; Flevoland was reclaimed from it.

5. 1953
   The North Sea flood

   1,836 people died in Zeeland, South Holland and North Brabant.

6. 1954–1997
   The Delta Works

   Dams and storm surge barriers, from the Oosterscheldekering (1986) to the Maeslantkering (1997).

7. 2000s
   Room for the River

   Instead of only higher dikes: wider floodplains and side channels so rivers can safely carry more water.

How a polder works

1. 1
   Build a dike around the land

   The dike keeps outside water out.

2. 2
   Dig ditches

   Rainwater and seepage collect in a network of ditches.

3. 3
   Pump the water up and out

   Once by windmills, now by electric pumping stations, into higher canals (boezem) and out to sea or river.

4. 4
   Keep the level right

   The water board keeps the water at an agreed level: too low damages wooden foundations, too high floods fields.