TECHNIQUES TO BETTER UNDERSTAND COMPLEX EPIKARST HYDROLOGEOLOGY AND CONTAMINANT TRANSPORT IN TELOGENETIC KARST SETTINGS

The movement of autogenic recharge through the shallow epikarstic zone in soil-mantled karst aquifers is important in understanding recharge areas and rates, groundwater storage, and contaminant transport processes. The groundwater flow in agricultural karst areas, such as Kentucky’s Pennyroyal Plateau, which is characterized by shallow epikarst and deeper conduit flow, is highly complex due to variable soil cover and heterogenous karstification in telogenetic carbonate bedrock, making it susceptible to contamination. To understand the epikarst storage and flow of autogenic recharge and its effects on contaminant transport on water flowing to a single epikarst drain in Crump’s Cave in Kentucky, we employed several techniques to characterize the surface-subsurface dynamics and hydrogeology of the system. During 2010-2013, water samples and geochemical data were collected up to every four hours before, during, and between storm events from a waterfall in Crumps Cave to track the transport and residence time of epikarst water and organic soil amendments during variable flow conditions. Flow paths and residence time were established through a series of dye traces, while geochemical data consisting of pH, specific conductivity, temperature, and discharge were collected continuously at 10-minute intervals, along with rainfall amounts and surface meteorological conditions. In addition, stable isotope data from rainfall, soil water, and epikarst water were collected weekly and during storm events. A shallow epikarst well and deeper aquifer well with continuous 10-minute stage height loggers provide data on the dynamics of recharge. The changes in geochemistry indicate simultaneous storage and transport of meteoric water through epikarst pathways into the cave, with the transport of contaminants occurring with variable timing through the systems diffuse and discrete flowpaths. This system provides a comprehensive overview of recent advances in data collection techniques in a well-developed karst aquifer, and the need for complementary and redundant data collection methods to capture high-resolution time series data to understand complex epikarst hydrogeologic processes.