The Maas is a 950 kilometer long river in Western Europe. The water level can differ a lot between summer or winter depending on the weather. If it rains heavely in the French and Belgian Ardens the water level rises dramatically and can cause heavy floods.
In 1993 on 22 december the waterlevel reached a record height of 45.9 meter above NAP. The flow rate peaked at 3120m³ per second. The average flow rate of the Maas is about 250m³/sec. In the summertime it can drop as low as 30m³/sec, in some places it's possible to cross the river on foot then.
In 1995 on january the fifth another major flood happened causing a lot of costly damage leading to a coöperation agreement between the Dutch and Flemish government. They have been working together since 1994 to prevent the floods and completed the resulting border Maas project in 2017.
One of the pictures above shows floods in 2011 at Roermond. Another shows the floods of 1993 next to a picture of dryer circumstances.

The Lieze weir is a weir in the river Maas in the Belgian province of Liège, in the municipality of Visé.
A hydroelectric power station is connected to the weir, which was commissioned in 1979. The plant has four turbines with a nominal capacity of 5,300 KW and delivers an average of 60 million KWh annually.
The weir also has an important function in regulating the water level in the Ternaaien Canal and the Albert Canal. The height difference at the weir is 6.7 meters. On the east side of the weir is a fish ladder.​