Assessing the effects of anthropogenesis on Appalachian flood severity: An eastern Kentucky case study

Flooding represents the complex interplay between drainage morphology, landscape hydrology, and precipitation. Precipitation patterns are influenced by interactions between atmospheric moisture circulation and topography, making steep Appalachian terrain vulnerable to extreme storms. Human activity alters surface hydrology and can exacerbate flooding of low-elevation areas where populations are densest. Mountaintop removal is a notable landscape change, but floodplains are also affected by construction of roads and other critical infrastructure and access limitations are addressed by reengineering river channels and building bridges. Though all of these may contribute to flooding, their relative importance remains equivocal. A July 2022 flood in eastern Kentucky provided the opportunity to validate a flood model incorporating major alterations to the landscape, then to iteratively test to determine which, if any, worsened flooding. While bridges, roads, and buildings had only minor effects on flooding despite their proximity to main channels and floodplains, discharge, flood height, and volume results were sensitive to channel narrowing and increased surface runoff facilitated by mountaintop removal sites. Lowering channel capacity decreases discharge and increases flood heights more than mountaintop removal, but mountaintop removal sites result in higher total discharge and operate as the primary contributor to flood volumes in the upper and lowermost portions of the watershed, highlighting a hydrologic sensitivity of the catchment to land use changes. Findings of this study serve to identify human-controlled factors most likely to contribute to future flooding and may thus inform mitigation efforts in eastern Kentucky and similar Appalachian catchments.