Southeast Water Scarcity Blamed on Overpopulation

Environment News Service. Posted October 23, 2009.

The most recent drought in the southeastern United States destroyed billions of dollars worth of crops, drained reservoirs and touched off legal wars among a half-dozen states, but the havoc came not from exceptional dryness but from booming population and bad planning, says a new Columbia University study.

Researchers from Columbia's Lamont-Doherty Earth Observatory have showed that the 2005-2007 drought was mild compared to many others and was no worse than one just a decade ago.

The study finds that climate change has played no detectable role in the frequency or severity of droughts in the region, and its future effects there are uncertain; but droughts there are essentially unpredictable, and could strike again at any time. The study appears in the October edition of the "Journal of Climate."

"The drought that caused so much trouble was pathetically normal and short, far less than what the climate system is capable of generating," said lead author Richard Seager, a climate modeler at Lamont-Doherty.

"People were saying that this was a 100-year drought, but it was pretty run-of-the-mill," he said. "The problem is, in the last 10 years population has grown phenomenally, and hardly anyone, including the politicians, has been paying any attention."

Region wide, the drought ran from late 2005 to winter 2007-2008, though many areas in the south were still dry until September, when the weather turned and flooding killed at least eight people.

Shrunken Lake Lanier, November 2007. (Photo by Robert Lz)

During the height of the dry period, Atlanta's main reservoir, Lake Lanier, sank more than 14 feet, usage restrictions were declared, and states sued each other and the federal government over use of water in rivers and reservoirs.

Seager and his coauthors Alexandrina Tzanova and Jennifer Nakamura put the period in context by comparing it with instrumental weather records from the last century and studies of tree-growth rings, which vary according to rainfall, for the last 1,000 years.

These records show that more severe, extended region-wide droughts came in 1555-1574, 1798-1826 and 1834-1861.

The 1500s drought, which ran into the 1600s in some areas, has been linked by other studies to the destruction of early Spanish and English New World colonies, including Jamestown, Virginia, where 80 percent of settlers died in a short time.

The 20th century was relatively wet, but the study showed that even the 1998-2002 drought was worse than that in 2005-2007.

The factor that has changed is population. In 1990, Georgia, which uses a quarter of the region's water, had 6.5 million people. By 2007, there were 9.5 million - a rise of almost 50 percent in 17 years.

The population is still growing with many people migrating into the region, but little has been done to increase water storage or reduce consumption, the study finds. There has been increased sewage discharge near water supplies, and lands have been covered with impermeable roofs, roads and parking lots, which allow rainfall to run off instead of storing it.

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