LANDSLIDE HAZARD MAPPING METHODOLOGY AND EXAMPLES FROM NORTH CAROLINA

In the Hurricane Recovery Act of 2005, the North Carolina General Assembly authorized the North Carolina Geological Survey (NCGS) to undertake landslide hazard mapping for 19 mountain counties. The NCGS has developed methodology to map landslide hazards in these counties. Preliminary office analyses using current and historical aerial imagery and LiDAR (Light Detecting And Ranging) digital elevation models are used within a GIS (Geographic Information System) to map possible slope movements and slope movement deposits. Fieldwork is targeted to verify the locations and nature of these features and to obtain soil, rock, and geomorphic data. This data are used as input parameters and calibration targets for the debris flow susceptibility model, and to populate a slope movement-slope movement deposits database. The results of the debris flow susceptibility model are then used to predict potential debris flow pathways.

GIS layers are produced for each county showing: the location of known slope movements and slope movement deposits; debris flow initiation susceptibility; potential debris flow pathways; and other pertinent geologic hazards such as zones of rock slope instability, and acid-producing rock units. These layers are designed for use by local government agencies and the public to help guide informed decisions on land use and public safety as increased development on mountain slopes exposes more people to landslide hazards

The poster shows examples from Macon and Watauga Counties where the mapping is complete. Mapping continues in Buncombe County, and landslide data is being collected throughout the region as needs and opportunities arise. Additional landslide information, including downloadable versions of the finished maps are available at http://www.geology.enr.state.nc.us/Landslide_Info/Landslides_main.htm. Hard copies and compact disks of the maps are also available through the North Carolina Geological Survey sales office at (919) 715-9718.