Land-use impacts on the hydrology of the Hidden River groundwater subbasin, Horse Cave, Hart County, Kentucky

Abstract

Hidden River Cave, located in the city of Horse Cave, Ky., forms one of the main tributaries of the Hidden River groundwater subbasin that spans multiple counties in south-central Kentucky. Hidden River Cave formed in Mississippian-aged carbonates and consists of a dendritic network of canyons and collapsed domes; a major trunk stream flows through the cave that supports myriad subsurface ecosystems and recharges the Mammoth Cave aquifer and the Green River, important water resources on which several communities depend. Poor land-use practices historically have contaminated the cave stream. As a result, the hydrology of the Hidden River groundwater subbasin has been extensively studied using fluorescent dye-tracing, and developments in groundwater resource management have improved cave conditions. However, land-use boundaries that intersect with areas of recharge still influence contaminant transport to groundwater. This study combined groundwater dye-tracing, high-resolution stage data collection, and supervised classification in a geographic information system (GIS) to assess land-use impacts on the hydrology of the Hidden River groundwater subbasin. Dye-tracing confirmed that stormwater infrastructure in Horse Cave discharges to Hidden River Cave, and, subsequently, the Hidden River groundwater subbasin. High-resolution stage data determined that the cave’s major trunk streams respond to precipitation within 40 minutes to 1.5 hours, while baselevel conditions, except after sustained precipitation, are met three to four days after precipitation ends. Supervised classification determined that development is concentrated in Horse Cave and has increased by approximately 7 % between 1989 and 2017. These results suggest opportunities for the implementation of karst-specific stormwater management regulations where such regulations are weak.