Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,000
Principal Investigators: Jason Polk
Abstract: Spring flow reversals in Mammoth Cave National Park were first recorded over 100 years ago, but a high-resolution study has yet to be conducted of the hydrogeological implications of how the Green River and the current, primary spring outputs of Mammoth Cave. A detailed investigation of the Caveâ€™s spring flow reversal phenomenon is necessary to capture seasonal and storm event variability and their influence on groundwater level changes and flow dynamics within the system as dictated by baselevel control of the Green River. This study aims to pilot a dataset quantifying the hydrological characteristics of recharge, sourcing, and timing of groundwater through the Echo River and River Styx Springs, which are primary outputs from Mammoth Cave into the Green River. Data will be collected for a minimum of nine months during major seasonal changes to capture changes in flow rates, groundwater sources, and isotopic mixing ratios in the karst system associated with recharge, river reversals, and flooding. High-resolution data will be collected for water levels (discharge) using data loggers. Sampling for oxygen and hydrogen isotopes, DIC and ions will occur weekly and once per day during storm events during the 9-month seasonal shifts from spring-summer-fall-winter and adjusted as needed to capture major storm event and hydrologic variability. Data are expected to show distinct changes in these parameters as storm events and flow reversals occur. Results from this study will provide Mammoth Cave National Park managers with information to help them understand the effects that spring flow reversals have on the caveâ€™s ecosystem, development, and future hydrologic regime, as well as how and where to establish long-term monitoring of hydrologic conditions that will assist with science-driven decision making to manage the Parkâ€™s ecological resources and safety, as well as assist the US Army Corp with managing dam releases that contribute to Green River level changes. The results will also be applicable to other river reversal systems in karst areas around the world, where impacts include flooding, contamination, and altered groundwater flow in wells, to assist in improving understanding and management of these areas.