This is a simple and cheap system for increasing the pressure of water. However, it is NOT the same as increasing the power.
Just like electrical power, if the current is held constant, the power increases with voltage. However the system's power performance will depend on the available current output as well.
For the water wheel to generate higher power, it is NOT enough just by increasing the pressure of the available water. The volume at that pressure is a factor as well.
This is just simple Physics.