No, this is a drainage canal, water from the polders is pumped into this canal and then the water is pumped into the river. The water level in this canal can be controlled by pumping more or less water from the polders. You can see that the water level in the polder on the right is lower than in the canal.

Flooding can happen close to the rivers and usually if they have been foolish enough to build in the floodplains.