Originally published in U.S. Geological Survey Karst Interest Group Proceedings, Rapid City, South Dakota September 12-15, 2005. Credit U.S. Geological Survey Department of Interior/USGS


The well-developed karst aquifers of south central Kentucky’s Pennyroyal Plateau are impacted by contamination from animal waste and other agricultural inputs. Understanding fate and transport of these and other contaminants first requires knowledge of flow and storage behaviors within the impacted aquifers, complicated by significant heterogeneity, anisotropy, and rapid temporal variations. Here we report on spatial and temporal variations in vadose zone flow and water chemistry (or quality) within Cave Spring Caverns, Kentucky beneath agricultural lands on a well-developed sinkhole plain. Weekly sampling of three underground waterfalls show statistically significant differences in water quality, though the sites are laterally within 160 m and are all located about 25 m underground, in a groundwater basin of about 315 km2. These reflect a combination of differences in epikarst flow and land use above the cave. High-resolution (minutes) monitoring of precipitation recharge along with flow and specific conductance in one of the waterfalls reveals a significant storage and mixing reservoir within the soil/epikarst zone. Varying precipitation rates and antecedent moisture conditions result in a range of storm responses observed at the waterfall, depending in part on whether this reservoir is filled or depleted. Slow and rapid flow paths through this storage zone were observed, the latter triggered by high recharge rates. These observations are generally consistent with the interpretations of Perrin and others (2003) from a Swiss limestone aquifer in a somewhat different hydrogeologic setting, strengthening the idea that epikarst and, more generally, vadose zone storage play a key role influencing flow and transport within karst aquifer systems.


Geology | Geomorphology | Hydrology