Epoch 1,000 Year Rain Event Hits Nashville
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June 2010 Volume 2 Issue 6 Epoch 1,000 Year Rain Event hits Nashville Inside this issue: cluding the 975 square mile Old Hickory Lake Watershed, Nashville Flood of 2010 2 had rainfall totals of 15 to 18 The Full Story. inches. This would translate to Army Corps of Engineers 3 over 200 Billion gallons of wa- struggled with dams and ter entering the Cumberland forecasts. River from the Old Hickory Old Hickory Dam — a 4 Lake Watershed alone. Controlled Free-Flow. Water was so high behind the GAC Flood Relief 5 Old Hickory Dam that if had- Telethon at the Ryman n't been released, the dam may Auditorium have collapsed. There was a staggering amount of water Your Property Location — 6 An enormous volume of ber 13th and 14th 1979. A Why Elevation Matters. released into an already swol- water descended upon the new calendar day rainfall len river on the evening of Nashville area the first two record was set when 7.25 May 2 and in the first hour that days of May 2010. The re- inches of rain fell on May the dam was opened to its full- cord rainfall for that two 2nd. This also established a est extent, there were 5.4 bil- day period was more than new record for the most lion gallons of water released double the all time record rainfall for any calendar day into the Cumberland River, for any two day event. The in Nashville's history. cresting at 26 feet above its flooding that resulted was In addition to Nashville, normal level at Nashville, 25 described by the U.S. Army many other counties, in- miles downstream. Corps of Engineers as a The Case for "1,000-year event.‖ Middle Tennessee: According the National No state income tax. Weather Service, rainfall Great property records were shattered the values. weekend of May 1st and Low property taxes. May 2nd, when copious Low auto and prop- amounts of rain fell across erty insurance rates. Middle Tennessee. In Nash- Great medical ville a new two day rainfall facilities. record was established when 13.57 inches fell on May 1st Four distinct seasons with mild and May 2nd which shat- winters. tered the previous record of 6.68 inches set on Septem- Pa ge 2 Volume 2 Issue 6 Nashville Flood of 2010 — The Full Story more urgent situation. That afternoon the National Weather For their part, Army Service issued flood warnings for Corps of Engineers offi- Middle Tennessee. Up to 10 inches cials say they see nothing had already fallen in some areas. Mill they would have done Creek, which feeds into the Cumber- differently — in fact, they land River across from Shelby Bot- say their actions pre- toms, had become so flooded that its vented even further dam- waters engulfed I-24, pushing cars age to downtown and a and even buildings along the inter- washout of the Metro- state. Even with the heavy rains, Center business district. much of Middle Tennessee contin- ued to conduct its business Saturday Two to 4 inches of rain afternoon. The morning of Saturday, May 1, Old Hick- was forecast for the Nashville area Sat- ory lake was resting normally, at 444 feet urday and Sunday — not the more than But at Old Hickory Lake, water be- above sea level, just as it had been the day 17 inches that fell in some areas. By gan rising quickly. Water was already before. But throughout the day the weather Friday afternoon, the weekend rain moving through the dam as usual to changed dramatically. Rains that had swept forecast had grown increasingly wet, generate electricity, but authorities in from the west intensified, and by the with some flash flooding expected. decided to open the spill gates to afternoon, creeks and tributaries through- relieve the growing lake levels at 1 While the weekend's rain forecast out Middle Tennessee were spilling over p.m. Saturday, according to Corps meant small tributaries and creeks their banks. records. Some question why they could fill up, the Cumberland was ex- didn't release more water earlier in By Sunday night, water was ripping through pected to handle the additional water preparation for the heavy rains. the heart of Nashville. The Gaylord Opry- without major flooding. But by Satur- land Resort & Convention Center had day morning things began to change. The standard protocol is not to re- evacuated 1,500 guests. Water was quickly The forecast put out for Sunday had lease water until a pool fills. Releasing rising into downtown streets. And residents grown worse as well, and Nashville and a little extra water can simply put in Bellevue, Antioch and other areas had the Cumberland watershed could be in more flooding on those farther been scrambling throughout the day to save the bull's-eye of the storm. downstream. Downstream, flooding any possessions they could — or simply was already under way as Mill Creek, survive the flash floods. The epic rainfall, along with calculations and decisions made by a series of agencies during the May 1st and 2nd weekend's his- toric floods, plays a central role in under- standing how this disaster was able to wreak so much havoc in Nashville and across the region. U.S. Sen. Lamar Alexander has promised a Senate committee hearing to understand what happened. Gaylord Entertainment Chairman and CEO Colin Reed continues to agonize over why emergency personnel had told him the Cumberland would stay below protective levees around the hotel, while his own security staff witnessed a Volume 2 Issue 6 Pa ge 3 Army Corps of Engineers struggled with dams, forecasts the Harpeth River, the Red River and streams that lace the area pouring up 2 feet from the night before to 447.88 other streams grew with the rainwater into the already racing and spreading feet above sea level, and it was getting that would to be dumped into the Mill, Richland, Whites, Browns and closer to the critical 452-foot mark. At the Cumberland. other creeks that feed into the Cum- 452 level, the Corps has few options. They At 5:30 p.m., the National Weather berland. either let the water flow over the dam, Service issued more flood warnings and At Old Hickory, from noon Saturday which undermines the dam, or raise the the dangerous conditions had spread to to 7 a.m. Sunday, the Corps made spill gates and create a controlled free-flow. counties to the east. By 7 p.m., the adjustments to the flood gates 10 The Corps was still hopeful on Sunday Cumberland River in downtown Nash- times as they struggled to manage the morning that they were going to keep ville had risen more than 10 feet that massive amounts of water that were Nashville below flood stage. Within hours, day. About this same time, downriver flowing from tributaries into the lake. those hopes were shattered. The heavy to the west at the Corps' Cheatham By 6:30 a.m. Sunday, the river in rains that morning kept pouring water into Lock and Dam, the crew there faced a downtown Nashville had risen nearly the Cumberland basin. By 10 a.m. Sunday, crisis. Rising waters were overtaking the 10 feet higher, and was just 3 feet downtown Nashville had reached flood entire facility, which is one of the below the 40-foot flood stage, ac- stage of 40 feet. The water level at Old smallest in the river. The crew shut the cording to Corps records, even turbines off and started to evacuate. though there had been nearly a They placed the mobile electronic seven-hour lull in the rain. equipment that operates the lock into Old Hickory Lake, while it looks trucks and left before the facility was large, is small when it comes to hold- submerged. Furniture and files in the ing storm runoff. It sits in the flow of office were destroyed. The floodwaters the Cumberland River, and was not moved in so fast and spread so wide designed as one of the four, deep that the Corps even lost parked vehi- flood control projects in the Cum- cles that couldn't be evacuated in time. berland system. The flood control But at this point, much of the Corps' projects are J. Percy Priest, Center Andrea Silva and Jamey Howell clung to Howell's Jeep as flood focus was around Nashville, with rain Hill, Dale Hollow and Wolf Creek. waters overtook the vehicle at the intersection of Saundersville continuing and the little fingerlets of The water at Old Hickory had gone Road and Lower Station Camp Creek. They survived the ordeal. Volume 2 Issue 6 Pa ge 4 Old Hickory Dam — a Controlled Free-Flow. fast. The Corps downtown Nashville on Monday, the had hoped to hold Corps' work was not done. The water back water from kept rising at J. Percy Priest Dam, Percy Priest, to reaching 504.01 feet by 6 p.m. Monday allow the waters as the water crested that same hour in from Old Hickory Nashville at 51.86 feet. to pass through The Corps' leadership believes the ac- downtown, and tions of their team during the 48-hour shave some feet storm that dumped a record 13 inches off the flood crest. at the Nashville Airport, and more in But the furious some places, lessened the possible dam- rains Sunday had age. They held the Percy Priest Dam disrupted that level above 444 feet, near the top of the plan. Waters at dam, from late Monday until late Percy Priest had Thursday, measuring releases to mini- Hickory Lake, above the dam, had climbed four feet Sunday to reach 498 mize problems downstream, they said.