HYDROGEOLOGY OF THE HIDDEN RIVER GROUNDWATER BASIN, HORSE CAVE, HART COUNTY, KENTUCKY

Subsurface drainage basins are highly interconnected in karst regions, as groundwater is quickly transported through conduits created by the dissolution of carbonate bedrock. South-central Kentucky is a classic example of a well-developed karst landscape and includes the longest-known cave system, Mammoth Cave. The Mammoth Cave karst aquifer contains 28 major groundwater basins, of which the Hidden River groundwater basin has been severely impacted by anthropogenic contaminants. Hidden River Cave, located in the city of Horse Cave, Kentucky, forms one of the main tributaries of the Hidden River groundwater basin that spans parts of Barren, Hart, and Metcalf Counties. 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 contributes recharge to the Mammoth Cave aquifer and supports myriad subsurface ecosystems. Poor land-use practices, including changing residential, commercial, and industrial boundaries, have historically contaminated the cave stream. As a result, the hydrogeology of the Hidden River groundwater basin has been extensively studied using fluorescent dye tracing techniques. Recent developments in groundwater resource management have improved cave conditions; however, land-use boundaries in Horse Cave that intersect with areas of recharge may still introduce contaminants into the groundwater system. This research characterizes recharge to Hidden River Cave via fluorescent dye tracing, cave stream discharge measurements, and geographic information systems analysis. Land-use in Horse Cave is also evaluated, as groundwater resource management varies between municipalities and counties. Further, this research provides a more detailed description of the Hidden River groundwater basin and provides scientific data to the American Cave Conservation Association for more informed management of Hidden River Cave.