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View Full Version : TVA, the Clinch, and the 1020 mark


Rodonthefly
06-14-2010, 04:05 PM
We all know TVA keeps the lake at 1020, after all the floods from Arkansa making the news here latly, do any of you guys offten wonder what would happen to us, if we got those rains? I know they have spill gates and all but it looks to me like with the unpredictable weather that we get here in east tennessee, they would play it safe and keep it a little lower then full pool.

waterwolf
06-14-2010, 10:46 PM
We all know TVA keeps the lake at 1020, after all the floods from Arkansa making the news here latly, do any of you guys offten wonder what would happen to us, if we got those rains? I know they have spill gates and all but it looks to me like with the unpredictable weather that we get here in east tennessee, they would play it safe and keep it a little lower then full pool.
Full pool is 4 feet below flood stage which is 1024. We would have to get absolutely dumped on to have the lake rise those 4 feet off of one event, it would take a foot or more of rain in 24 hours. They can drop the water about .5-1 foot a day with the flood gates open and sluicing, from the recent times when they have had to dump water.

I will say that the tribs are very sensitive to rainfall right now however, the slightest amount and they come rocketing up, and are taking forever to fall out.

silvercreek
06-15-2010, 07:37 AM
They can hold it even higher if they have to. Top of the gates is shown as 1034. As a note,both Old Hickory dam and Percy Priest just above Nashville came within inches of the top of the gates In May. At that point the Corps had to let the water go on Nashville or risk losing the dams all together.

silvercreek
06-15-2010, 07:51 AM
PS if you want to see how much a lake can rise click on this link and see when Percy Priest lake rose 15 feet in just a couple of days. Impressive.
http://www.lrn.usace.army.mil/hh/resplots/jpp_a.html

waterwolf
06-15-2010, 09:50 AM
I would think surface area makes a huge difference in how fast a reservoir will rise. I don't know the surface area of norris or percy priest, but think Norris is one of the larger reservoirs in the system, and from what I can remember ( not much BTW) it rises pretty slow compared to other, since it only has two real headwater sources. I could be completely full of it as well

silvercreek
06-15-2010, 09:59 AM
You would be correct about surface area i think. The drainage area would make a big difference also. The Percy Priest drainage is fairly large. In some areas of that drainage they got between 15 and 20 inches of rain in two days if I recall correctly. Heck, Interstate 24 in the Priest drainage became a river with a large portable classrom floating down it. Don't generally think of interstates becoming feeder streams. Silvercreek

Rodonthefly
06-15-2010, 10:13 AM
Hmmm interesting info, thanks guys, and i hope we don't ever have to worry about this problem

waterwolf
06-15-2010, 02:22 PM
You would be correct about surface area i think. The drainage area would make a big difference also. The Percy Priest drainage is fairly large. In some areas of that drainage they got between 15 and 20 inches of rain in two days if I recall correctly. Heck, Interstate 24 in the Priest drainage became a river with a large portable classrom floating down it. Don't generally think of interstates becoming feeder streams. Silvercreek
You know there is probably pretty good holding water created on an interstate which is flooded, the new jersey median probably creates some magnificent seams.

I tried a google search for Norris, but came up emtpy. I will keep looking to see what I can find out.

silvercreek
06-15-2010, 02:52 PM
From the Corps site and the TVA site, Norris holds almost exactly twice as much water. 1,113,000 vs 652,200 acre feet for Priest. The news at the time showed a little girl who caught by hand a Koi about 12 inches long as it was swimming in a parking lot. I thought I spotted a rise in my basement over by the water heater.