Highway Landslide Hazards in Indiana—Construction and Analysis of a Landslide Inventory

Landslides are geologic hazards that occur throughout Indiana. Landslides are most prevalent in the southern half of the state, with two main landslide clusters in southeast and south-central Indiana. This paper discusses the construction of a landslide hazard geographic information system (GIS) data layer compiled from Indiana Department of Transportation (INDOT) sources. Landslide areas were identified using a digital elevation model (DEM) derived from light-compliant detection and ranging (LiDAR), a ground surface slope-angle map, and orthoimagery. These tools were used to map repaired and unrepaired landslide areas along highway infrastructure. The study explores the relationship between landslide areas and various geological (bedrock, karst, and seismicity), climatic (rainfall), and anthropogenic (coal mining and land cover) factors. It finds that bedrock geology and the lack of a glacial cover are closely related to the occurrence of landslides. Areas with high landslide incidence closely relate to predominating shale bedrock formations and variable topography. Inclinometer data revealed that many landslides occur within the weathered bedrock zone where factors such as soil moisture and groundwater fluctuations play a role in landslide movement. The development of this study’s landslide inventory is anticipated to aid landslide susceptibility maps, risk assessments, andemergency management within the state.