Black Mountain resident Harry Hamil was alarmed. According to new flood maps released by the N.C. Department of Crime Control and Public Safety in October, a 100-year flood would place much of his property at 151 Ridgeway Ave. underwater.
Even apart from any danger, the change could cost Hamil dearly, since the maps help determine insurance rates, property values and allowable uses for specific parcels. And while the new maps show portions of the Swannanoa Valley at considerably greater risk of flooding, some residents question their accuracy.
“Is it in danger because the land itself is too low, or is it because the map has some problems?” wonders Hamil. “My answer at this point is that it appears to be due to an error in the map.” On Nov. 11, Hamil filed an informal appeal with the state flood-mapping program, citing errors in the “base flood elevation” data used by the state, which is meant to indicate the crest of a 100-year flood (a flood so severe that there’s only a 1-percent chance of it occurring each year).
Homeowners aren’t the only ones affected by the new findings. The maps also show Ingles’ current distribution center in Swannanoa at risk. The regional supermarket chain ranks among the area’s largest employers.
But Buncombe County Floodplain Administrator Cynthia Barcklow says the new maps are more accurate than the previous ones, because they rely primarily on LIDAR (light detection and ranging) data to determine elevations. “There’s much better data than there was 10 years ago,” she says.
The county Planning Department began getting calls about the new maps last summer, and interest has continued unabated.
“A lot of realtors and surveyors started calling around July, asking, ‘Do you have them yet?’ But since the maps were released, we’ve been hearing a lot more from property owners,” notes Barcklow.
For now, the new maps are still considered preliminary—they won’t be binding until they’re published in the Federal Register sometime next year. A 90-day appeal period will run from Dec. 6 to March 4, 2008, allowing property owners to contest the maps’ findings.
The revised flood maps resulted from a partnership between the Federal Emergency Management Agency and the state. The devastating 1999 flooding in eastern North Carolina associated with Hurricane Floyd was the impetus for the new round of maps, replacing those issued in 1996, which proved inaccurate.
The maps can impact landowners in a number of ways. Many lenders require homeowners with federally backed mortgages to have flood insurance if their home is located in the 100-year floodplain. A shift in the floodplain means that property owners could suddenly be facing substantially higher costs.
Randy Mundt, North Carolina’s hazard mitigation officer, attributes the changes to better data. “The maps right now are more than 11 years old,” says Mundt. “Conditions in Buncombe County have changed since 1996. There’s more development. There’s more development upstream. There’s less ground for the water to soak in, so it’s running off parking lots and rooftops and getting into streams faster.” The earlier maps were done largely by “approximate methods,” he says, often relying on decades-old topographic maps with inexact contour lines.
Mundt’s office had additional data to use when mapping Buncombe County; after the 2004 floods here, the city of Asheville contracted with the engineering firm Brown and Caldwell to do a floodplain study, which Mundt says showed significantly higher discharge rates into the watershed than previous studies had.
“We said OK, we’d like to be able to use that information,” says Mundt. “Of course, we reviewed it to make sure it was accurate.”
What puzzles Hamil, however, is the fact that the new maps dramatically expand the floodplain at his end of the county while showing little change elsewhere. “You go and pick any other place in the county, and chances are you won’t find squat in the way of expansion,” he says. “In fact, you’ll find contraction in a lot of places.”
That expansion, he believes, has major implications. “The single biggest development project in the history of the Swannanoa Valley is in danger,” he says. “The economic impact will be huge.”
If future manufacturing-and-distribution projects are stymied by the risk of flooding, Hamil predicts a “radically changed” economic future for his hometown.
“If these maps are upheld, then Black Mountain will have little chance of being more than a bedroom community for Asheville,” he predicts.