The entire water level control and wave creating structures can quickly flatten against the river bottom. This technology has been successfully used around the world for decades.
The water level upstream of the wave is controlled by gates built on the river bottom:
When a flood is coming the gates lay flat on the river bottom. There are a number of options for shaping waves that also collapse to the river bottom.
The wave creating technology will be chosen at a later stage of the development process.
No Flood Risk
Waves on a river do not increase flood risk. The wave may reduce flood risk by making more room for water flow during the excavation of the river bottom during installation.