Cylinder/piston pressure multiplier River flow water pump

I am not a CAD user, and the trial of a perspective below is to assist in the understanding. Hope that it is reasonable.
The optimization with the extra impellers and centrifugal water pump are in the drawing board. The impellers will work as one horizontal water wheel in which the water passes between the impellers and the shaft (body of the bigger cylinder).
The pump is fish friendly, and if a cluster of pumps are installed along the river or the beach tidal the electric hydro turbine can be of any size, depending only on the number of pumps installed.