LEGACY LAND USE LINKED TO PRESENT-DAY LANDSLIDE HAZARDS IN VICKSBURG NATIONAL MILITARY PARK, VICKSBURG, MS

Vicksburg National Military Park (VICK) is located on loess bluffs flanking the Mississippi River in Vicksburg, Mississippi, approximately an hour west of Jackson. In early 2020, a series of extreme precipitation events resulted in mass movements, flooding, and other hydrologic effects that had impacts on both the park’s infrastructure and its cultural and natural resources. In addition to the landslides and mass movements, erosion of the region’s steep and gullied slopes contributed to in sediment deposition in perennial drainages and bayous, altering the park’s drainage. The area was further compromised by subsurface erosion (soil piping) that resulted in sinkholes, erosion, and subsidence (Ashland, 2020). The underlying geology is predominately composed of Qal eolian loess and Qpl pre-loess terrace sand and gravels (O’Meara and Winter, 2021). A thick layer of eolian loess, comprising the Memphis, Morganfield, and Natchez soil series, blankets these geologic units throughout the park. These loess-based soil units have eroded into steep to very steep hillsides, bluffs, or uplands, with moderately-high water movement occurring in the most restrictive layer. The USGS collaborated with the Vicksburg National Military Park to collect field data and investigate the occurrence of mass movements in the park. These efforts aim to inform mitigation strategies for future erosion-based hazards. As part of these overarching objectives, this study developed historical digital elevation models (DEMs) and orthophotos from 1938 and 1962 aerial imagery to examine the relationship of land cover with mass movements and terrain change. The findings revealed a correlation between agricultural land use practices from the 1930s with present-day landslide occurrence.