A GEOCHEMICAL COMPARISON OF TWO TELOGENETIC KARST SPRINGS DURING REVERSE FLOW, MAMMOTH CAVE, KENTUCKY

Previous studies in Mammoth Cave National Park have identified a phenomenon, referred to as stable reverse flow, that may significantly contribute to cave formation. Groundwater in the Mammoth Cave Karst Aquifer typically discharges from springs into the Green River, the regional hydrologic baselevel. When the river stage increases, water from the Green River enters River Styx Spring, flows over the drainage divide, and discharges at Echo River Spring. This study aims to quantify the geochemical and hydrologic changes that occur between the two springs during stable reverse flow. The stage of the Green River, influenced by storm events in the Upper Green River Basin, seasonal changes associated with evapotranspiration, and damming along the Green River, all control the timing and duration of stable reverse flows. Data is being collected to capture seasonal changes in karst geochemistry, flow rates, groundwater sources, and carbon transport in the karst system. Major ion concentrations, alkalinity, TOC and carbon isotopes are collected weekly; SpC, temperature, and pH are being recorded at 10-minute intervals; and pressure transducers are being used to collect water levels at two-minute intervals. Data are expected to show relationships between stable reverse flows, meteorological processes, and human influence on the river basin. Distinct changes in geochemical parameters will be used to determine when flow reversals occur. Alkalinity, TOC, and carbon isotope measurements will provide information about seasonal and temporal changes in carbon flux, and about how spring flow reversals contribute to carbonate dissolution and conduit development.