Example:  
A waterwheel is optimized by a water quantity of Q = 250 l / s .
It works in a range from 25 l / s … to …ca. 500 l / s .

Specification / calculation
D = 4000 mm Hw = 4200 mm Q = 250 l/sec  (200 days/ year)
cell filling = 0,45 %      speed = 1,35 m/sec
segment - rim ( radial ) = 330 mm
   0,250 m³/s
segment - rim
( broadness )
=
--------------------------
1,25 m  
 
0,33 m x 1,35 m/sec x 0,45

number of cells : 10 x (4,00 - 0,33) = 36,7

chosen = 40 cells = 20 segments
 

ventilated cells

 
.…natural power generation
Looking at the slow rotation ( here 6,45 Rpm ) waterwheels are not dangerous for fish and small organisms , but can be helpful with their wanderings. Besides they support the rivers with O 2 supply.