UA Researchers: Drought Brings Stream Flow to Lowest Point in at Least Seven Years

TUSCALOOSA, Ala. – Its impact isn’t sudden. Its definition isn’t even precise. However, a drought’s economic effect is often much more severe than other weather-induced disasters, say two scientists in The University of Alabama’s Center for Freshwater Studies.

And adding this summer’s multiple days of 100-plus degree temperatures to the dry mix magnifies the problems.

“Unlike floods, hurricanes or tornadoes, droughts sort of creep up on you,” said Dr. Amy Ward, director of the Center and a professor in UA’s biological sciences department. “It’s a cumulative thing. There really aren’t even a lot of exact definitions for drought, but it’s generally defined as an extended period of dry conditions.”

Major droughts have been known to cost the nation as much $40 billion, Ward said. By comparison, severe flooding of the Mississippi River in 1993 resulted in an estimated $28 billion in damages and Hurricane Andrew, one of the nation’s costliest storms, rang up a $25 billion price tag.

How dry is it? Well, one way to gauge the results of reduced rainfall is by measuring the flow rate of streams. UA’s researchers have closely monitored a wetland area within the Talladega National Forest in Hale County for the past seven years. The scientists measure and monitor a host of environmental conditions in this area, including the flow rate of a stream that feeds into the wetlands.

“This is, by far, the lowest flow we’ve seen in seven years,” said Dr. Milton Ward, an associate professor of biological sciences. “It is less than half of our normal summer base flow.”

The UA researchers are interested in learning how plants adapt when stressed by such things as low rainfall. Complications from this summer’s dry spell are compounded by last winter’s unusually dry conditions, Amy Ward said.

And, if history is a guide, it may get worse before it gets better.

“Typically, our drier weather period begins in August and goes through October,” she said.

Faculty in UA’s Center for Freshwater Studies are developing, along with faculty from the University of New Mexico, a research proposal outlining ways to define drought and assess its impact in river basins of Alabama and New Mexico. The National Science Foundation notified these researchers that it is awarding them a $100,000 planning grant over the next 12 to 18 months to develop the proposal.

Since the state began tracking rainfall amounts in the 1920s, Alabama has seen five major droughts, with the most recent stretching from 1984 until 1988, Amy Ward said.

The lack of rainfall can be a contributor to high temperatures in more than one way, Milton Ward said. The absence of the cooling effects of cloud cover compounds the problem, as does the lack of moisture available for evaporation.

Just as perspiration evaporating from a person’s skin cools that surface, moisture evaporating from the earth’s surface cools it, he said.

“What if there is no moisture on your skin?” he asks. “It just gets hotter and hotter.