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.

Cylinder/piston pressure multiplier River flow water pump

Optimization using shrouded impellers on the side and one extra centrifugal water pump

I am an Angolan, southern Africa.

I have a design for a submersed water pump for river flows working only with the river flow.
We can fabricate simple machines in Angola, and cylinder/pistons assembly is easy.
Two cylinders, one with 1 meter diameter and the other 0.2 m/diameter. Pistons are in the same shaft. Area ratio is of 25 X. Pressure ratio of 25X.
The bigger cylinder has a diffuser of a diameter of 1.5 meter in both ends and is open on both sides.
When we submerse it in the river flow, the water flows in and pushes the piston. On the other end of the cylinder the water flows out in the direction of the river flow.
It is a shrouded cylinder with a diffuser and two half diffusers, like impellers to move the system around.
The piston pushes the second piston, in a closed cylinder (0,2m/d) and pressures water. The inlets and outlets of this double side cylinder have retention valves to control aspiration and discharged of the cylinder.
The cylinders rotate on its axis, enabling continuous cycles.
It is a water pump that uses only the river water flow.