How do Dams Work?
Dams are one of humanity’s oldest innovations. We may have borrowed the idea from the beavers, but human ingenuity has taken dam-building to incredible heights. Dams serve many functions: flood control, navigation, water supply, power generation and even recreation. Dams are, essentially, edifices of concrete built on a river to back up the water on one side. Depending on the purpose of the dam, it may have locks and a series of gates, called spillways, or it may have only a powerhouse and turbines. A good example of dams that serve all the aforementioned functions are those in the Tennessee Valley Authority system in the Southeastern United States. Many of the TVA dams have become vital parts of the river’s ecosystem. One hundred years ago, the Tennessee River was wild and narrow, running its 600 or so miles from east Tennessee, down through northern Alabama, and then turning north, back into western Tennessee, before it emptied into the Ohio River in Paducah, Kentucky. The river floo
