Monday, February 11, 2019

Worst case scenario for Table Rock Dam!

The worst-case scenario of a catastrophic floodwater discharge from Table Rock Lake using the auxiliary floodgates would roughly resemble this: 

Water Level at 931 Feet:  Table Rock Lake is at full flood capacity. The ten Tainter gates are opened to accommodate additional lake inflow from the White River Basin including the James River and Beaver Lake discharge.

Water Level at 937 feet: Table Rock Lake is now 6 feet above flood capacity. The ten Tainter gates are opened wider in an effort to stabilize reservoir rise. Outflow from the Lake under these circumstances will be nearing 200-300 thousand cubic feet per second (CFS).

Water Level at 942 feet: Table Rock Lake is 11 feet above flood capacity and at its "design pool", or the maximum elevation that the reservoir is engineered to reach, under "probable maximum flood" scenarios. The dam’s ten Tainter gates will be fully raised to their maximum height of approximately 30 feet letting loose 550 thousand CFS into Lake Taneycomo. This scenario would effectively submerge and destroy the powerhouse, power transmission grid, hatchery, and wreak serious destruction down stream. An illustration of how Table Rock’s ten spillways might appear under these circumstances mimics this: the floodgates will extend up and out from the structure, like eyebrows, shadowing the concrete spillways!

Water Level at 947 feet: Table Rock Dam would be at its maximum capacity and water would be at the very top of the dam. The auxiliary spillway would be brought online, in concert with Table Rock’s fully opened floodgates. This catastrophic or "last resort" protocol releases 1 million CFS of lake waters into Taneycomo and deals dreadful destruction to Branson, Hollister, Point Lookout and possibly the Powersite Dam. At this point there is a danger of water overtopping the concrete dam and breaching the earthen structure, which imminently leads to cataclysmic structural failure and the uncontrolled release of the Table Rock Lake impoundment—nearly 3 million CFS of water.

Historically, Table Rock Lake has experienced a record crest of 935.47 feet, which occurred on April 27, 2011.

In December 2015, the dam released 72,000 CFS at its peak. This is the highest amount ever released! [Information source: https://en.wikipedia.org/wiki/Table_Rock_Lake]

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