What is 'water head' in the context of hydroelectric dams?

In the context of hydroelectric dams, 'water head' refers specifically to the height of the water column that exerts pressure on the bottom of the dam. This hydraulic pressure drives the turbines that generate electricity. The greater the height of the water column, the more potential energy is available to be converted into kinetic energy as the water flows downward, thereby increasing the pressure behind the turbines.

The concept of water head is essential because it directly correlates with the amount of energy that can be generated by the hydroelectric system. Essentially, it is not just about the volume of water or the structure of the dam, but rather the effective pressure created by the elevation of the water above the turbines. This measurement is crucial for assessing the potential energy that can be harnessed for electricity generation in a hydroelectric dam setup.