The Delfland water system: Boezem and polders
A large part of the area in which the Delfland Water authority operates lies below sea level. We call these low-lying areas polders. When it rains, the water is drained via the drainage canals in the polders. Every polder has one or more pumping stations (in times past these were the windmills). These contain powerful pumps that pump the water from the smaller drainage canals into a large storage canal, known as a boezem canal. The boezem canal is always higher than the polder which it drains.
The boezem canals transport the water to the edges of the Delfland operating area, where more large pumps are situated: the boezem pumps. These pump the water out to sea, or into the river, the Nieuwe Waterweg.
So a pumping station is in essence a large pump. Each pump is fitted with a weed screen to keep out debris and ducks that may otherwise cause blockages. See the illustration showing the polder pumps and the boezem pumps.
Fig. On the right the sea with the waterway in which the water from the polder is discharged. The pumps pump the water from the polder (mainly the lowest-lying area) to the storage boezem, then into the waterway, from where it is discharged into the North Sea.
Or see the film below: How does the boezem system in Delfland work?
Picture captions (from left to right):
1 Film: How does the boezem system in Delfland work?
2 Schematic diagram of the polder and boezem system