First published study of 2009 Atlanta floods may hold clues to recent urban flooding in other U.S. cities-warnings, too

September is normally a hot, dry month around Atlanta, Ga. The first hints of autumn usually don’t arrive until the end of the month, if then. So it was a surprise last fall when record rainfall turned much of the metro area and north Georgia into a lake, plunging such attractions as Six Flags Over Georgia underwater and in places exceeding flood levels expected only once every 500 years.
Now, in what is likely the first scholarly published study of the floods, a team of climatologists, meteorologists, geologists and hydrologists, led by the University of Georgia, has shown that a convergence of record-setting events, perhaps unprecedented in the area’s history, combined to cause tens of millions of dollars in damages and at least 10 deaths.

And while the future of such floods is unclear, as are possible ties to global warming, conditions may be ripe for a reoccurrence, said Marshall Shepherd, lead author of the study just published in the online edition of the Bulletin of the American Meteorological Society.

“More frequent or intense flooding events, coupled with expanding impervious surfaces like roads and parking lots, will affect the ecosystem and the very fabric of societal infrastructure,” said Shepherd. “We are thus going to need revolutionary designs, management and policies if we are going to mitigate the impact of future events.”

Other authors of the paper are Thomas Mote, John Dowd and Mike Roden, who with Shepherd are in the UGA Franklin College of Arts and Sciences; Pamela Knox of the Office of the State Climatologist; Steven McCutcheon of the U.S. Environmental Protection Agency; and Steven Nelson of the National Weather Service in Peachtree City, Ga.

Recent studies have noted that regions of the southeastern U.S. face an increasing vulnerability to climatic extremes because of population growth and the addition of impervious surfaces. The floods this year in Oklahoma City (June) and Nashville (May) point out how serious the issue has become, and even in a sparsely populated area of Arkansas, authorities reported at least 19 dead in a flash flood in June.

But even the knowledge of an increased threat couldn’t have prepared metro Atlanta leaders for what befell them last September.

“Just as an example, the U.S. Geological Survey measured the largest flow ever recorded on Sweetwater Creek near Austell, which has a streamflow record dating back to August 1904,” said Shepherd. “And a climatological assessment by the National Weather Service showed that September 2009 was fifth wettest in Atlanta’s history.”

While newscasters and commentators have turned the phrase “perfect storm” into one of the most-used clichés of the age, no two words describe better what led to the Atlanta flooding, the new research shows.

First, of course, was the massive and unrelenting rainfall, caused by an odd combination of events. Prior to the record rainfall in north Georgia, a low-pressure system stalled over parts of a three-state area called “ArkLaTex,” pulling moisture from the Gulf of Mexico. Many days of rainfall nearly saturated the soil and filled many streams, rivers and reservoirs over the Southeast. Remnants of two tropical storms in the Pacific and Atlantic (and evaporation from the Gulf of Mexico) generated some of the wettest air observed over the Southeast. Inherent instability in the atmosphere and the mountains northwest and north of Atlanta produced “training” or repeated heavy rainfall.

The spark that set the floods metaphorically afire, though, may have been all the concrete and paving of the metro area itself. The water, unable to soak into the ground, overfilled sewers and drainage and flooded roads, schools, neighborhoods, Interstate-20 and Six Flags Over Georgia, all designed to rarely be submerged.

Satellite data, multi-sensor Doppler radar estimates, traditional National Weather Service gauges and a relatively new community volunteer network, defined the multifaceted causes of flooding during the event.

“Though the meteorological set-up was unique, the role of Atlanta’s impervious surfaces and rapid continued growth should not be missed,” said Shepherd “This increase in roofs, roads and parking is known to alter runoff intensity and, in the future, make flooding potentially just as bad and in many cases worse.”

Another possibility is that large cities may initiate or alter storms through so-called heat-island, convergence and pollution effects. How (or if) this played a part in the Atlanta floods will be the subject of future research by Shepherd, who plans to recreate the event using computer simulations, though without Atlanta included.

“The September 2009 flooding that definitively ended the drought in Georgia is consistent with the Intergovernmental Panel on Climate Change projections that the frequency and severity of extreme hydroclimate events such as droughts and floods will likely increase,” the authors say in their study—bad news for areas such as Atlanta, Nashville and Oklahoma City, which have had enough already.

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Test well water to insure it's safe to drink, use

Clean drinking water is a top priority for families. But homeowners who rely solely on well water can be open to certain risks.

If your water is provided by a city or county source, it isn’t necessary to have it tested unless an in-house contamination is suspected. Public and municipal water supplies are routinely tested and must meet Environmental Protection Agency standards.

Homeowner's responsibility

Well water can become contaminated from various sources and can make homeowners sick. Since there are no federal or state monitoring regulations for private wells, it is the homeowner’s responsibility to make sure their well water is safe to drink.

Well water may not be safe to drink if:

You have frequent and unexplained illnesses in your household.
Your neighbors find toxic chemicals in their well water.
You are concerned about the lead pipes or soldering in your home.
You detect a difference in the taste, smell or color of the water.
You are buying a new home with a well that has been out of use.
It comes from an improperly sealed or unprotected well, spring or cistern.
You spill fertilizers, pesticides, oil, gasoline or other toxic substances on the ground in or near the well.

Water isn't just for drinking

Poor water quality not only affects drinking water. It can also affect a variety of household functions. Contaminated water used for cooking may affect your health, while an excess of certain minerals can hamper cleaning tasks in laundry or bathroom.

Unfortunately, no single test can provide information on all possible contaminants.

Bacteriological tests determine if water is free of disease-causing bacteria. But there are many types of tests that cover a variety of bacteria. The most common bacteriological test checks for E. coli and total coliform bacteria, which can come from fecal contamination.

Mineral tests can determine if the mineral content is high enough to affect either health or the water’s aesthetic or cleaning capacities. This test often pinpoints calcium, magnesium, manganese, iron, copper and zinc. An abundance of these minerals can cause hard water, plumbing and laundry stains or bad odors.

Pesticide and chemical tests are generally performed only if there is reason to believe a specific contaminant has entered the water system, such as pesticides.

Inspect regularly

It is important to regularly inspect your well for sources of contamination.

Other potential problems can exist with the slab, the well screen, the building covering the well or landscaping. University of Georgia Cooperative Extension offers well assessment through the HOME*A*SYST program. These self-assessments determine the risks associated with your well.

If you suspect a problem with your well water, contact a licensed well driller to inspect the well and have it tested for bacteria. This test should be done at least once a year, especially after well water disinfections.

Have water tested

Well testing can be done through local UGA Extension offices. Water samples are tested through the UGA Agricultural and Environmental Services Laboratory in Athens.

A basic test, which tests for pH, hardness and more than 15 minerals, is $15. An expanded water test, which tests for minerals, soluble salts and alkalinity, is $50.

Contact your UGA Extension office at 1-800-ASK-UGA1 for information on troubleshooting water quality issues or testing your well water for bacteria.

Contact your county health department for information on how to take proper care of your septic system. Septic system problems can affect well water quality.

By Paul Pugliese
University of Georgia

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Georgia's summer likely warmer, drier than normal

Georgia’s summer will likely be warmer and drier than normal through at least early August. Temperatures and rainfall in late summer and early fall will depend on the number and tracks of tropical weather systems.

The early summer following an El Niño winter climate pattern – like we had this past winter -- is typically warmer and drier than normal. With the warmer temperatures and drier-than-normal conditions, soil moisture will quickly decrease over the next two months. However, because of the abundant rain this past winter and early spring, water resources are expected to remain in good shape across the state through this summer.

Tropical question

By August the southeastern U.S. will be entering into the heart of the tropical storm season. Will temperatures remain high and rainfall low? At this point, it’s hard to say. Again, this will depend on tropical weather systems. At this time, we do not have the ability to forecast the tracks of tropical storms this early in the season. We can only give general forecasts of the number of storms.

The number of tropical storms this summer is expected to be above normal. Atlantic Ocean and Gulf of Mexico sea surface temperatures are currently above normal. This favors the formation of tropical systems, including tropical depressions, storms and hurricanes.

An additional factor favoring the development of tropical systems is the atmosphere transitioning from an El Niño climate pattern to a neutral climate pattern. Neutral and La Niña climate patterns favor the formation of tropical weather systems. The oil spill in the Gulf of Mexico is not expected to have any impact on the number nor on the intensity of tropical weather systems.

Transition time

An El Niño climate pattern typically transitions into a neutral pattern for several months. However, it appears that the ocean-atmosphere system will only spend a few months in the neutral pattern before changing into a La Niña pattern.

Historically, the East Coast, including Georgia, is more likely to be directly impacted by hurricanes when the atmosphere is in the La Niña climate pattern. There is a good chance that atmosphere will be near transition to or in a La Niña by the heart of hurricane season.

As Georgia enters the winter, it appears that we will be in a La Niña climate pattern. Typically this means that south Georgia can expect winter to be warmer and drier than normal. Across north Georgia, a La Niña climate pattern generally brings a warmer-than-normal winter. For north Georgia, a weak La Niña climate pattern is associated with near-normal to wetter-than-normal winters. However, a moderate to strong La Niña climate pattern is associated with drier-than-normal conditions across north Georgia.

It is too early to know if this winter will bring a weak, moderate or strong La Niña climate pattern. If the La Niña climate pattern develops this winter, then Georgia may be set up for a drought in 2011.
Up-to-date weather information is available at the website www.georgiaweather.net. Historic climate data is available at the website climate.engr.uga.edu.

By David E. Stooksbury
University of Georgia

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Prepare for Rising Water

Precautions taken at the first sign of rising water can help save lives and help minimize damage during a flood. Typically, your standard homeowners insurance policy will not cover flood damage, though federal flood insurance is available through most insurance agencies, if your community participates in the National Flood Insurance Program. If you have flood insurance, your agent will advise you how to file a claim.

Whether you have flood insurance or not, Allstate recommends you take the following steps as soon as a flood watch is issued, or news of rising water hits, which may prevent thousands of dollars in unnecessary damage.

-- Keep informed by listening to a battery-operated radio. That way, you
can track the storm or follow the progress of rising water and make a
better decision about any further action that you should take,
including the possibility of evacuating your home.

-- Fill bathtubs, sinks and containers with clean water so you will have
a ready supply in case the community's water supply becomes
contaminated.

-- Move outdoor possessions indoors, such as patio furniture, chairs and
bicycles.

-- Elevate valuable furnishings and possessions from basements or first
floors to upper floors or move them away to higher ground if you have
time.

-- If advised by local authorities, shut off all utilities including gas,
electricity and water.

-- Prepare to evacuate by gathering your emergency supplies. Don't forget
flashlights and extra batteries, essential medicines, cash, credit
cards, food, water and a battery-operated radio with extra batteries.
If you have pets, make sure they have an adequate supply of food and
water, in a safe place, on an upper floor, or prepare to take the pets
and such provisions with you. Do not leave pets chained or fenced
outside.

-- Once rising waters reach your home, school or business, your first
priority is occupant safety. If you're advised to leave, do so
immediately and follow the evacuation instructions given. Travel to
higher ground by whatever means is available and stay there. The
sooner you leave the better your chances of avoiding flooded,
congested roads.

-- Do not attempt to drive through flooded roads. Turn around and go
another way. If your car stalls, leave it immediately and walk to
higher ground. More people drown in their cars than anywhere else
during floods.

-- If avoidable, do not attempt to walk through floodwater. Drowning is
the top cause of death during floods, in many cases because people
underestimate the power of even a small amount of water. A mere six
inches of quickly flowing water can knock you down. In areas covered
by standing water, use a long pole or stick to make sure the ground is
firm. Be especially cautious with children.


Information on the National Flood Insurance Program can be found at http://www.fema.gov/business/nfip/.

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