[ml_giant]

I did some googling since I was also curious and found this stellar article: https://energyeducation.ca/encyclopedia/Hydraulic_head

TL:DR: "Head differences of 100 meters or higher are considered high head. In this type of plant, water travelling through the turbine comes from a significantly higher elevation, meaning that the system needs a smaller volume of water to produce an equivalent amount of energy.[1] These systems generally also require smaller turbines since there is less water flowing through the turbine."

[cratermoon]

The ideal place for a hydroelectric dam is what's called a slot or "gunsight" canyon. Narrow and high, to create the best conditions with the smallest dam. Dams in wide, relatively flat places like along the Columbia River exist, but they are multi-purpose, built for flood control, irrigation, navigation (with channels and locks), and recreation benefits in addition to hydroelectric.

[digdugdirk]

Props for finding a simple yet thorough article explaining many of the terminology used in other responses in this thread. Thank you.