2019: Second wettest year on record for the Tennessee River basin according to TVA
The wet start to 2020 comes on the heels of an above-normal year of total rainfall in 2019.
The entire Tennessee River basin received about 66 and a half inches of rainfall in 2019, according to TVA, placing last year as the second wettest year on record behind the wettest year of 2018 (67.02”).
Those records date back 130 years.
"We still get flooding. We can't prevent all flooding, but we can do our best and use the system as it was designed to minimize that to the extent that we can," Tom Barnett, TVA River Management General Manager, said of TVA’s dam system.
TVA's river management helps prevent damages to structures along the mainstream flow system, saving money compared to if TVA didn't exist.
"Damages averted in 2019 - TVA reservoir system prevented about $1.8 billion in the Tennessee Valley, and that's including the about $1.6 billion in Chattanooga," Darrell Guinn, TVA River Operations Support Manager, explained.
About $1.4 billion of that $1.6 billion Chattanooga 2019 total came only from February’s heavy rain. The Valley's 2019 damages averted total is the highest on record for TVA.
More than any other city, Chattanooga receives the greatest benefits from TVA's dam set-up due to its geographical location.
"Where all the rainfall that falls in the northeast Tennessee Valley, it eventually has to make it through Chattanooga, and Chattanooga is kind of the bottleneck of the river system and the drainage area," stated Guinn.
TVA uses real-time operational forecasting and adjustments, taking into account many factors such as soil moisture, groundwater, runoff, hydraulic conditions, and the national weather service rain forecast.
"We had an event there a couple of weeks ago in north Alabama, and so we have aggressively recovered our flood storage to put us in good position for this rain event," Guinn explained.
The current event means that they're spilling at Nickajack Dam and additional dams downstream through into Kentucky while holding water back in tributaries.
"We came out of spill on Tuesday at Chickamauga. We do expect pool to rise a little bit above normal pool level for this time of year," Guinn said of the conditions for the current rain event.
How far above normal the water will rise on Chickamauga will depend on exactly where the heaviest rainfall occurs over the next day or two. Guinn added that they may have to go back to spilling water at the Chickamauga Dam.