Research suggests water wars brewing in Southeast
Water scarcity in the western United States has long been an issue of concern. Now, researchers studying freshwater sustainability in the U.S. have found the Southeast, with the exception of Florida, does not have enough water capacity to meet its future needs either.
“For more than a century, the Southwest has been the focus of long-running legal disputes over water resources, but the Southeast is now becoming a more contentious region for water use,” said Dr. Will Graf, a geographer in the University of South Carolina’s College of Arts and Sciences.
Graf said 25 years ago, journalist Marc Reisner wrote, “Cadillac Desert: The American West and Its Disappearing Water,” which predicted that water resources would be unable to support the growing demand of cities, agriculture and industry in the Southwest. A paper co-authored by Graf featured in this month’s journal, “Proceedings of the National Academy of Sciences” supports most of Reisner’s conclusions, using data and methods unavailable to Reisner in 1986.
Although the paper focuses on freshwater sustainability in the Southwest, Graf and co-authors Dr. Tushar Sinha, an engineer at North Carolina State University, and Dr. John Kominoski, an ecologist at the University of Georgia, said the findings have important implications for the Southeast as well.
“It turns out that the Southeast has a relatively small margin of water surplus for the future,” said Graf, USC’s Educational Foundation endowed professor and a leading authority on science and policy for public land and water.
Graf said the water resource picture in the Southeast is becoming similar to the Southwest, where water disputes have long been a prominent part of policy and resource management. In South Carolina, the Water Withdrawal and Permitting Act, which became law this year, and the agreement between North Carolina and South Carolina on managing their common rivers, such as the Catawba-Wateree system, demonstrate that water resources are gaining increased attention.
“Who would have guessed that instead of Arizona vs. California, we may have South Carolina vs. Georgia?” Graf said. “The looming issue of providing enough water for Atlanta and the possibility of reaching to the Savannah River for water for Atlanta is an example of the coming debates over our region’s water.”
For water supply to be considered sustainable, the researchers calculated that no more than 40 percent of freshwater resources should be appropriated for human use, to accommodate flow variability, navigation, recreation and ecosystem health.
They also determined how much water each region of the United States needs to meet all its municipal, agricultural and industrial demands and compared the need to the amount of fresh water in streams and rivers. The assessments did not include groundwater resources.
The researchers found that neither the Southwest nor the Southeast have enough water to meet their needs. With the exception of Florida, Southeastern states have their largest cities in interior, piedmont locations where water-storage reservoirs and watersheds are increasingly unable to supply enough water for agriculture, industry and municipal uses, said biologist and co-author Dr. John Sabo of Arizona State University.
While there are more reservoirs in the East, they are smaller than their Western counterparts, Graf said. These smaller reservoirs are more susceptible to evaporation losses than larger ones. Most of these smaller reservoirs in the Southeast are designed to capture precipitation that falls within a year, so changes in precipitation rapidly influence reservoir water levels.
“The recent droughts in the Southeast during the summers of 2002, 2005 and 2007 indicate severe water shortages due to very low rainfall, and water supply is dependent upon precipitation, which is likely to be more uncertain in the near future,” Sinha said.
In addition, the fragmentation of river networks because of dams threatens biodiversity in the Southeast, one of the most diverse ecosystems in North America, Kominoski said.
The authors cautioned that the paper’s estimates are conservative and are based on data from 1950 – 99. They do not include the previous decade, which had some of the highest temperatures and most extreme droughts, along with population increases.
“Also, the estimates don’t take climate change into account,” Kominoski said. “We expect to have less precipitation in the summer, during the growing season, and more severe droughts. As population grows, so does demand for water.”
In addition to Graf, Sinha, Kominoski and Sabo, the paper’s authors included Dr. Laura Bowling, Purdue University; Dr. Gerrit Schoups, Delft University of Technology; Dr.Wesley Wallender, University of California, Davis; Dr. Michael Campana, Oregon State University; Dr. Keith Cherkauer, Purdue University; Dr. Pam Fuller, U.S. Geological Survey; Dr. Jan Hopmans, University of California, Davis; Dr. Carissa Taylor, Arizona State University; Dr. Stanley Trimble, University of California, Los Angeles; Dr. Robert Webb, U.S. Geological Survey; and Dr. Ellen Wohl, Colorado State University.