The Tennessee Valley Authority recently released data that was collected during, and after, Tropical Storm Helene that provides insight into the magnitude of the storm that swept across the Appalachian region beginning September 27.
Using computer modeling, TVA tracks what might have happened without dams and flood mitigation as a way of helping determine how well its system is operating. That data collectively informs “flood damage averted” calculations.
Data from this event shows that flood mitigation strategies enacted by TVA prevented approximately $406 million of potential damages in Lenoir City, Chattanooga, Kingsport, Elizabethton, Clinton, and South Pittsburg.
Since TVA’s inception in 1933, more than $10 billion in potential flood damage has been averted.
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Providing flood control of the Tennessee River is a core mission of TVA and has been since its inception more than 91 years ago, it noted.
“Evaluating rainfall and stream flow data from across the Valley provides engineers in TVA’s state-of-the-art River Forecast Center the information to make operational decisions to minimize flood impacts along the river system 24 hours a day, seven days a week, 365 days a year,” it said.
“This was some of the highest flood levels we’ve seen in the Tennessee Valley in its entire history,” said James Everett, TVA’s general manager of river management. “We saw a record amount of flooding and we saw tremendous amounts of rainfall that caused that flooding. TVA’s dams and the people who manage these dams stepped up to that challenge and managed this record setting event.”
TVA’s ten large tributary reservoirs stored 404 billion gallons of water during the weather event. Two months of normal rainfall in just 3 days to the Tennessee River Watershed.
The reservoir system and its ability to store water during floods led to significant overall reduction in flood crests in communities along the river system. Without TVA’s system of dams, the river stages at Lenoir City, TN, and Chattanooga, TN, would have been about 21 to 23 feet higher than the observed levels during Helene. Nolichucky Dam withstood nearly twice the flow of Niagara Falls.
"No one could have imagined the destruction Hurricane Helene would unleash on our community and our utilities. One of the first calls I received was from TVA to understand how dire our situation was. TVA provided valuable support, manpower, and equipment to aid in our restoration of power and early damage assessment at our wastewater treatment plant," said Lee Brown, Erwin Utilities President and CEO. "TVA enabled us to move quickly and efficiently in our work to recover from Helene. Our partnership with TVA and other local power companies is the perfect example of the benefits provided by Public Power."
