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Southeast could become an overdeveloped ‘megalopolis’ in the next half century

The Southeast U.S. region used in this study. (Terando et. al/PLOS One)

Giant urban sprawl could pave over thousands of acres of forest and agriculture, connecting Raleigh to Atlanta by 2060, if growth continues at its current pace, according to a newly released research paper from the U.S. Geological Survey.

“We could be looking at a seamless corridor of urban development,” said Adam Terando, a research ecologist with the USGS and an adjunct professor at North Carolina State University who was the study’s lead author.

The development will engulf land from North Carolina to Georgia, and possibly spread to Birmingham, Ala., “if we continue to develop urban areas in the Southeast the way we have for the past 60 years,” he said.

Combining USGS demographic modeling with North Carolina State’s High Performance Computing Services and analyzing the data for six years, Terando and his five co-authors estimated that urbanization in the Southeast will increase by up to 190 percent.

It will nearly mirror the decades-old development of the Northeast corridor, from Washington to Boston, Terando said, and in Florida from Jacksonville to Miami. “I would say that’s definitely a future that the study is pointing toward,” he said.

Land cover change metrics shows projected urbanization for 200 model simulations for the study region and twelve ecoregions. Abbreviations are as follows: BR – Blue Ridge, CA – Central Appalachians, IP – Interior Plateau, MACP – Mid Atlantic Coastal Plain, MAP – Mississippi Alluvial Plain, MVLP – Miss. Valley Loess Plains, P – Piedmont, RV – Ridge and Valley, SP – Southeastern Plains, SCP – Southern Coastal Plains, SFC – South Florida Coastal Plain, SA – Southwest Appalachian. (Terando et. al/PLOS One)

Development on that scale would result in losses of 15 percent of agricultural land, 12 percent of grasslands and 10 percent of forests, the study said. It would take the form of tract housing developments, business centers and thousands of miles of paved roads.

The research paper was published last month in the journal PLOS One. Its co-authors include Jaime Collazo and Alexa McKerrow, also researchers at USGS, and Curtis Belyea and Rob Dunn, researchers at North Carolina State.

“The upshot is that . . . climate change isn’t the only story in the Southeast,” Terando said. “There are large-scale human impacts on our environment . . . the way we develop.”

Numerous species of animals would be left with no habitat. The loss of woodlands that soak up rainfall would leave local waters more vulnerable to the storm-water runoff that washes nutrient pollution from lawns and motor oils from roads, in addition to increased garbage.

Carbon from automobile traffic down a more crowded Interstate 85 corridor would add to the ills contributing to climate change.

“The drawbacks are obviously things like more traffic,” Terando said. In Raleigh, there are a thousand miles of streets, and 2 percent to 3 percent must be repaved each year, according to the USGS, meaning more tax dollars will be needed to repair more roads.

A megalopolis is pretty much what it sounds like — a giant city or sprawl that spreads over a region. It is described as an urban complex comprising many major cities. Between Raleigh and Atlanta along the study corridor are Greensboro and Charlotte, N.C., and Greenville, S.C. Nearby are Columbia, S.C., and Birmingham.

Land cover change in patch metrics between 2009 and 2060. (Terando et. al/PLOS One)

Over the past 60 years, the Southeast has grown 40 percent larger than the rest of the United States, the study said, with 77 million people living in a region where development has been suburban and highly dependent on cars.

The biggest change will likely happen in what the study called the Piedmont eco-region between Atlanta and Charlotte, cutting through South Carolina. The largest proportion of change, where land will be noticeably transformed, is expected to be in the Southwestern Appalachian region.

But models are rigid and do not account for uncertainty or change. They cannot predict how local leaders will plan to develop land or whether they will use more ecologically friendly methods of development.

“Unless we change course . . . urbanization will have a more pronounced ecological impact in many non-coastal areas of the Southeast than climate change,” said Jennifer Costanza, a research associate at North Carolina State and another study co-author. “It’s impossible to predict the specific ecological outcomes . . . but so far, the projections are not good in terms of biodiversity and ecosystem health,” Costanza said.

Darryl Fears has worked at The Washington Post for more than a decade, mostly as a reporter on the National staff. He currently covers the environment, focusing on the Chesapeake Bay and issues affecting wildlife.



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