Tennessee Valley could see 17 more inches of rainfall, UT researcher says

Tennessee Valley could see 17 more inches of rainfall, UT researcher says

January 4th, 2013 by Pam Sohn in Local Regional News

The sun sets over Missionary Ridge in this view from Lee Highway and state Highway 153.

Photo by Tim Barber /Times Free Press.

Illustration by Laura McNutt /Times Free Press.

Illustration by Laura McNutt /Times Free Press.


• In more than 100 years of record-keeping, annual rainfall in the Tennessee Valley has ranged from 30.65 inches in 2007 to 65 inches in 1973.

• If the new research is correct, that annual rainfall could increase to a range of 47 to 82 inches.

• Tennesseans could see more intense heat waves with heat-wave temperature increases of about 4 to 6 degrees Fahrenheit.

A UT researcher has completed a first-of-its-kind study to predict heat waves for the top 20 cities in the eastern United States.

Looking 50 years ahead, the findings place the Tennessee Valley in the cross hairs of climate craziness -- more intense heat waves and drastically wetter weather.

"Heat waves will become more severe in most regions of the eastern United States, and both the Northeast and Southeast will see a drastic increase in precipitation," said Joshua Fu, a civil and environmental engineering professor.

Using Oak Ridge's Titan and UT's Kraken supercomputers, Fu calculates Nashville will see heat-wave temperature rises of almost 5.8 degrees Fahrenheit higher than now, and Memphis will see heat wave temps up by almost 4 degrees.

As for rain?

Both the Northeast and Southeast will experience 35 percent increases in precipitation -- or more, according to the research.

"The Southeast has the largest increase in both daily extreme precipitation and annual extreme precipitation days," Fu's report states.

The Tennessee River's drainage area already is one of the rainiest in the United States. A Tennessee Valley Authority Web page says local rainfall averages 51 inches a year.

A 35 percent increase would mean another 17 inches of rain.

The new research findings add new weight to concerns about extreme weather.

Given weather swings from droughts to superstorms, many planners have worried in the past decade about what the future holds for the climate of the eastern United States and especially the Southeast.

All climate models have generally shown the Southeast will be hotter in years to come, but this is the first study to predict intensity increases in heat waves for specific cities -- the top 20 cities.

As for rain, other models have been largely inconclusive about whether the region will be wetter or drier.

And this particular research makes TVA's plan to spend millions shoring up dams against a never-seen-to-date "maximum probable flood" look good.

TVA began the effort several years ago when Nuclear Regulatory Commission requirements changed and TVA discovered an error and found changes were needed in its river flow modeling.

TVA officials said Thursday they have seen Fu's new research and could not yet comment on it.

Some national and regional groups also already are looking at ways to protect land and wildlife as climate change evolves.

An announcement last week about the preservation of 11,364 acres of Cumberland Plateau wilderness in the ecologically significant Paint Rock River watershed of Jackson County, Ala., is part of that effort.

The Open Space Institute is working in the Southern Appalachians to provide research and money to help land trusts and government agencies protect the region, one of the most biodiverse places in the world.

To help, the Chattanooga-based Benwood and Lyndhurst foundations partnered with the Merck Family Fund and Open Space Institute to create a $6.7 million fund for land acquisition or preservation.

Peter Howell, executive vice president of the Open Space Institute, said the group has identified lands throughout a 3 million-acre region in Northeast Alabama, Northwest Georgia and Southeast Tennessee that now are being targeted for conservation.

Understanding impacts

Most Americans have no problem connecting the potential health effects of a rain-slick highway or a tornado with their health.

But making that connection with climate change has been more elusive.

Few understand that better than Fu, whose research on heat waves was funded by the Centers for Disease Control and Prevention.

He was looking to predict the future potential for heat waves because they spark pest-borne illnesses such as Lyme disease and West Nile virus, he said.

Although he started with 20 of the country's 50 largest cities -- those in the eastern United States -- he soon will be looking at the largest cities west of the Mississippi.

After that, he will take the information from those two studies and look at the impacts of those predicted heat waves on air quality.

"The heat waves will make air quality -- especially ozone problems -- get worse," Fu said.

Amber Boles, spokeswoman for the Chattanooga-Hamilton County Air Pollution Control Bureau, said that's because the pollution released by burning carbon fuels needs three more key ingredients to make smog: high temperatures, lots of sun and low humidity.

"So if we're having a heat wave, we're going to have higher ozone," she said.

The result is a spiral. Ozone begets climate change, and the resulting heat waves exacerbate more ozone that pushes climate change.

"They affect each other," said Fu, 49.

"But our purpose is not to preach climate change. Our purpose is how we can get a better life -- like better air quality," he said.

"If we reduce our emissions, it will reduce human risks and get better air quality. And then we maybe won't get climate change -- or such extreme events."