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How TVA Stops Floods

The best time to stop a flood is before it starts, right? That’s exactly what TVA tries to do.

TVA uses its network of dams to reduce flood damage by holding back the water from heavy rains in reservoirs. These “flood-storage” reservoirs (usually located on “tributary rivers”—rivers that run into the main Tennessee River) do most of the work in controlling floods.

  photo of house wrecked by flood  
  Before TVA, flooding plagued the Tennessee Valley in late winter and early spring.  
Big storms—the ones that can cause flooding— are most likely to hit the Tennessee Valley in the winter and early spring. So, to make room for this water in the flood-storage reservoirs, TVA lowers their water levels by January 1 each year. The water in tributary reservoirs can rise and fall as much as 60 feet per year.

When a storm hits, TVA holds the water back by closing the gates of the dams in areas where it is raining. When the rain stops and the danger of downstream flooding is over, TVA lets the water out at a gradual rate to get ready for the next storm.

As you might expect given how much it rains, there were lots of floods in the Tennessee Valley before TVA dams were built. These floods washed away the topsoil, causing problems for farmers. Even worse, hundreds of people died and thousands more lost their homes and farms. The city of Chattanooga, Tennessee, would flood about once a year. Click here to find out why.

Today, TVA’s system of dams and reservoirs prevents about $224 million in flood damage along the Tennessee, Ohio, and Mississippi Rivers every year.

do you know? much water it would take to wash a car away? Click here for the answer

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