THE DUAL PURPOSE OF RIDGETOP GROUNDWATER IN THE DANIEL BOONE NATIONAL FOREST: LOCAL AND REGIONAL CONNECTIONS

Appalachian ridgetops commonly have isolated ephemeral wetlands that store water at high elevation and provide breeding grounds for amphibians. These wetlands have been associated with perched groundwater in the Daniel Boone National Forest (DBNF), Kentucky although the dynamics and volume of ridgetop groundwater need to be quantified to show local and regional importance. Our research objective was to match subsurface structure data to a multi-year hydrological dataset for ridgetop wetlands in DBNF to quantify groundwater-surface water controls on ridgetop hydrology. Data from a total of 6 natural and 4 constructed ridgetop wetlands was collected between 2016 and 2020. Temperature normalized hydrograph recession rates and water table gradients were calculated from surface water and groundwater levels at each site. Water budgets were determined using precipitation data and open water volumes calculated from elevation data. Wetland subsurface structure was mapped using a soil probe. Cores were correlated based on soil texture, color, and density to make a 2-D cross-section the sites. Our results show that subsurface leakage to lowlands are a significant and variable outflow pathway. The geometry of a subsurface aquitard boundary causes depressions of variable size that collect groundwater, which influences the transition between regionally and locally connected scenarios. A regional connection was created when groundwater tops subsurface depressions. In this state, groundwater flows off the ridge towards valley bottoms, which connects the upland water with the lowlands. When groundwater falls below subsurface depressions, the flow becomes more static while local vegetation continues to consume these pockets of water.