When generating hydropower, the head is the distance that a given water source has to fall before the point where power is generated. Ultimately the force responsible for hydropower is gravity, so a hydroelectricity plant[1] with a tall/high head can produce more power than a similar plant with a short/low head. In short, for a given water flow, a larger head will be converted into greater kinetic energy. That energy is then harnessed by a water wheel or water turbine to create usable hydropower.
- ^ Alternatively, again for a given water flow, a larger head could produce the same power with smaller equipment.