Question

What will be the effect on electricity generation, if the channel taking water to turbine starts at point C? 
 

Hint:

Power from a hydroturbine is roughly proportional to head and flow; lowering the intake level reduces head and therefore reduces power output.

Answer 1

Point C is at a lower water level than points A and B, so the vertical head available to the turbine is reduced when water is taken from C. Reduced head means lower potential energy per unit mass of water, producing less kinetic energy at the turbine runner; the turbine therefore receives less torque and rotates more slowly, so the generator produces less electrical power. If the head and flow fall below the turbine's design limits, generation may become inefficient or stop altogether. Secondary effects include increased flow rate required for the same power, higher relative losses, and possible cavitation if operating conditions are unsuitable.