ASSESSING LANDSLIDE SUSCEPTIBILITY USING LIDAR DATA IN KNOX COUNTY, NEBRASKA

This study is designed to assess landslide susceptibility using elevation data from LiDAR and soils data. Data were assessed using qualitative and quantitative approaches using logistic regression within a geographic information system. A landslide susceptibility map was developed for Knox County, Nebraska, located along the Missouri River valley. The Missouri River valley has significant changes in relief, gradually receding into rolling loess hills further to the south and southeast of the county. The six factors selected in determining the area’s susceptibility to landslides, were parent material, soil type, land cover, slope percentage, slope curvature, and slope aspect. The types of parent material in Knox County include shale, sandstone, siltstone, glacial till, alluvium, and eolian sand. Previous investigations in the region indicate the cretaceous shale is a major contributing factor in landslide development. Physical map units were acquired to differentiate the soil type and parent material. Digital elevation models derived from LiDAR were analyzed in GIS to provide slope percentage, curvature, and aspect information. Logistic regression data was extracted from randomly selected points along landslide scarps. All six factors were classified to identify areas that are least likely and most likely to experience landslides. Differential weighting of factors was applied to produce a resultant map to show landslide susceptibility. The resultant map locates and distinguishes areas that are more likely to incur landslide activity or areas that have already experienced a significant amount of landslides. The factors considered to have the most influence on landslide formation were high slope angles, north facing slopes, and Cretaceous shale bedrock.