LANDSLIDE INVENTORY OF NORTHERN KENTUCKY USING DIFFERENTIAL ELEVATION MAPS DERIVED FROM SEQUENTIAL LIDAR SURVEYS

Direct costs of landslide remediation such as road repairs in the State of Kentucky exceed 10 million per year in public funds. Translational and rotational mass movements in Cincinnati and Northern Kentucky occur frequently in colluvium derived from the Ordovician-aged bedrock, in glacial deposits and in anthropogenic fill. While landslides are a well-known natural hazard in northern Kentucky, they are difficult to catalog and monitor because of the steep forested slopes that characterize the region. For this study elevation difference maps were produced from 2-ft. resolution bare-earth DEMs derived from LiDAR data flown in 2007 and 2012. Landslides were delineated by identifying areas that have lost elevation (scarps) adjacent to areas that have gained in elevation (toes). To date approximately 75%, of Kenton & Campbell counties in Northern Kentucky have been examined and 101 landslides have been identified. Nine of these had been previously reported and cataloged by the Kentucky Geologic Survey, and 92 were newly identified. Of these newly identified landslides, 8 have been field-verified and 65 have been confirmed by observing landslide features such as scarps, and damage to trees and infrastructure in historical air photos accessed using Google Earth. The aerial size of the mass movements ranges from 25 ft. long (scarp to toe) by 20 ft. wide to 350 ft. long and over 600 ft. wide. In eighteen locations remedial measures including the construction of retaining walls, sewer-line exhumations, the regrading of slopes and road repairs were observed. Approximately 45% formed in colluvium derived from the Ordovician-aged shale-rich Kope Formation, 32% in the limestone-dominated Fairview and Bull Fork Formations, and the remaining 23% in quaternary glacial deposits, alluvium and fill. Additional attributes such as the direction of movement, elevation loss and gain, landslide type, date of movement, land use and geomorphic position were also recorded. These factors, along with lithology, soils, and DEM derivative maps such as slope, aspect and landform classification are used for analysis and modeling of risk factors associated with landslide activity in the region.