Pumps, weirs, and locks

A pumping station is a pump that can lift water from a low to a high level and pump water into and out of an area. Pumping stations enable us to maintain the water at the agreed level. We use four types of pumping stations: reservoir pumping stations, sluice pumping stations, polder pumping stations, and sewage pumping stations.

Boezem pumping station

A drainage pumping station pumps excess water into a drainage basin. A drainage basin is a system of lakes or canals in which we temporarily store water. We also use drainage basins to drain water. An example of a drainage pumping station is De Waterwolf in Lauwerszijl/Electra. In 1920, De Waterwolf began its important task in the Reitdiep: draining water from a large part of the province of Groningen and the northern part of Drenthe. De Waterwolf was unique for its time and is a beautiful piece of industrial heritage. Today, the pumping station is still in operation. In fact, it is indispensable for draining excess water into the Wadden Sea.

Peeling machine

A shell pumping station is a special reservoir pumping station that we use in areas where the ground is subsiding. The ground in North Groningen is subsiding due to gas extraction. If the water level remains the same and the ground subsides, the water level will rise in relative terms. To counteract the negative effects of land subsidence, Noorderzijlvest lowers the water level. An example of a shell pumping station is the Abelstok pumping station, located in the Hoornsevaart between Mensingeweer and Wehe-den-Hoor. This pumping station is located in the second shell of the Electra reservoir.

Polder pumping station

A polder pumping station pumps excess water in the polder to a reservoir. We have approximately 140 polder pumping stations in our working area. One example is the Leutingewolde polder pumping station. Here, we measure the water level of the Leekstermeer lake. The lake also collects too much water during wet periods. That is why the lake must be able to cope with higher water levels. We regulate this here with a polder pumping station.

Sewage pumping station

A sewage pumping station pumps used water from homes and businesses through the sewer system to the treatment plant. One example is the monumental Groningen sewage pumping station on Damsterdiep. It pumps all the used water from the city of Groningen through an eight-kilometer-long pipe to the sewage treatment plant in Garmerwolde. The immense pumps in the pumping station provide the pressure and push the water to the treatment plant, as it were.

Locks are built between two waterways that have different water levels. On one side of a lock, the water is higher or lower than on the other side. We can open a lock to allow water to flow through. There are eight types of locks:

Schutsluis

The lock is the best-known type of sluice. The lock takes a boat from one water level to another. This is how it works:
A lock has two doors. One door opens and the boat enters the lock. The door then closes.
We raise or lower the water in the lock chamber. This depends on the water level on the other side of the lock. Finally, the second door opens and the boat continues on its way.

Sluice gate

We use floodgates to keep water out. When the water level is normal, the floodgate is open. When the water level is very high or very low, we close the floodgate. An example is the Oosterschelde storm surge barrier in Zeeland.

Drainage sluice

Drainage sluices can be found in quays, dikes, and dunes. We use these sluices to drain excess water from the land into a reservoir, canal, river, or sea. An example of this are the Cleverings sluices in Lauwersmeer.

Relief valve

We only open the relief sluice after a flood. When we open the sluice, water from a polder can flow into a canal, river, or sea.

Inlet sluice

We use the inlet sluice for two purposes. We open the sluice to allow fresh water to flow into city canals or agricultural areas, for example.
We open the sluice when it is very dry. If we open the sluice in the Gaarkeuken, for example, water from the IJsselmeer flows into the ditches and canals in our working area.

Spigot

Sluice gates are found in seaports. The sluice ensures that the channel between the sea and the port does not silt up with mud. Behind the sluice is a large bowl-shaped hole. At high tide, we allow water to flow into this bowl. When the water is at its highest, we close the sluice. At low tide, we open the sluice and the water flows out of the bowl back into the sea. The water carries the mud in the channel with it.

Floodgate

Inundation is a fancy word for 'flooding'. This lock allows us to flood a piece of land. In the past, the inundation lock was used by the army for defense. They ensured that the water was too low to sail on and too high to walk or drive through. Now we use the lock to allow water to flow into reservoirs. Or to flood agricultural land.

Dock lock

A dock lock can be found in harbors. This lock ensures that there is water in the harbor at low tide. This means that the boats are always in the water. Is it high tide and is the water level high? Then we close the lock. This keeps the water in the harbor when the tide goes out.

A weir is a valve in a ditch or canal. Behind it, the water remains in place to keep the water at the agreed level. A weir can be fixed or movable.

• A fixed weir always provides the same water level.
• With a movable weir, we can use a valve to ensure different water levels. The water level is lower in winter: we open the valve to drain off excess rainwater. This prevents flooding. The water level is higher in summer: we close the weir to retain water for agriculture and nature during dry periods.