Nuts and bolts of landslide mapping
Macon County was the first to be targeted under a statewide initiative launched in 2006 to map areas prone to landslide in the mountains.
Over a one-and-a-half-year period, a team of state geologists led by geologist Rick Wooten surveyed 770 locations in Macon County and found 165 landslides evident from photo records between 1951 and the present.
The bulk of the slides have occurred on public land, on the highest reaches of the mountains. Landslide risk increases critically at 22 degrees of slope or right around a 40 percent grade, according to the data collected during the mapping project.
Macon County was the first to be systematically mapped because of the Peeks Creek slide, which killed five people when it ripped down the mountain for 2.5 miles. Watauga County came next because it has the most landslides recorded, followed by Buncombe because it has the most people. Jackson County is slated to be surveyed this year, with Haywood County next in the queue.
The landslide hazard mapping program creates a comprehensive database of historic slides and potential slide pathways that can be integrated with a county’s GIS maps. They can help emergency management officials plan evacuation procedures, but they can also help shape policy.
While Wooten said he is not in the business of making policy recommendations, he did have a definite idea of what his research has taught him.
“One thing that comes through in all the work we’ve done is there has to be a wholesale approach to where and how people build on steep landscapes,” said Wooten.