Some canal locks pump water back, - "The hydraulic cylinders enable the water used by the locks to be pumped back. Up to 48,000 cubic metres of water are displ

Some canal locks pump water back, - "The hydraulic cylinders enable the water used by the locks to be pumped back. Up to 48,000 cubic metres of water are displaced in a single lockage operation. In periods of low discharge on the Meuse, the screws can pump back the water lost due to the passage of a ship through the lock to the upper canal reach." https://www.inlandnavigation.eu/power-of-water-and-wind/ https://www.inlandnavigation.eu/power-of-water-and-wind/