Monday, September 30, 2024

1913-1972 Nolichucky Dam on Nolichucky River south of Greeneville, TN

(Satellite)

An aftermath of Hurricane Helene in Sep 2024.

"On September 27 at about 11:30 p.m. ET, out of an abundance of caution, TVA issued a Condition Red alert, which meant that a breach was imminent." As of 9am Sep 28, Local Emergency Management Agencies had ordered evacuations. As of 4pm, TVA rescinded the Condition Red alert because water levels were receding at about 1 foot an hour. "The Nolichucky Dam peak water elevation hit 1266.0’, which is 9.5 feet over the record elevation of 1256.5’ set on November 6, 1977. The 1.3 million gallons per second [174kcfs] flow rate at 11 p.m. on September 27, more than doubles the flow rate of 613,000 gallons per second [82kcfs] from the previous regulated release in 1977." [TVA_news] To put 174kcfs in perspective, I think the flow rate that wiped out the spillway of the Oroville Dam was about 100kcfs. A Knoxville News Sentinel summary said the "flow reached nearly twice Niagara Falls." But the article was behind a paywall.

0:19 video
This is the Nolichucky Dam in Greene County in East TN. TVA says the dam is still intact, but they continue to assess the situation. 🙏

I think this is the TVA video that was the source for the above post.
 
TVA posted
⚠️ Out of an abundance of caution, we have issued a Condition Yellow for Nolichucky Dam in Greene Co., TN.
A Condition Yellow indicates that the dam is approaching its threshold to withstand excessive floodwater, necessitating immediate action. The dam structure has not failed.
Local county emergency management officials are coordinating evacuations as appropriate.
Extreme rainfall from the remnants of Hurricane Helene is causing record river levels.

Facebook reel
 
I noticed that they are not letting traffic cross the bridge.
wjhl

This is a normal flow over the dam.
Street View, Mar 2023

This is the lowest flow I could find with Street View.
Street View, Nov 2023

This was the highest flow I could find with Street View.
Street View, Jul 2013

TVA
"The dam is 94 feet [29m] high and 482 feet [147m] long."
The hydroelectric equipment was removed in 1972 because the reservoir filled with sediment. I could not determine what the capacity was when it was built. It was built to generate electricity.

Normally, I can find a dam on a river by looking for a skinny line next to a fat line. But in this case the river is as wide below the dam as it is above the dam. That means the river is in a steep canyon.
Satellite


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