ANALYZING TIME-SERIES DATA OF CAVE DRIPS IN JAMES CAVE, VIRGINIA: IMPLICATIONS FOR STORAGE AND RECHARGE IN APPALACHIAN KARST SYSTEMS

Karst aquifers, characterized by soluble rocks such as limestone and dolostone, provide drinking water to 20-25% of the world’s population and are thus critical global water sources. However, recent work suggests that rapid alteration of karst aquifers due to the impact of climate change on precipitation patterns may affect recharge to these aquifers and ultimately decrease their storage.

Much of the research on recharge in karst aquifers has relied on using patterns of spring discharge to quantify recharge. Springs allow for continuous monitoring of discharge, making them accessible field sites. However, because springs can integrate multiple flowpaths, it is difficult to rely on spring discharge patterns to get information on where and how karst aquifers are receiving recharge. Monitoring closer to the source of recharge in a karst watershed (i.e., caves, sinkholes, soil) allows for a more accurate analysis of recharge timing and mechanisms.

This study aims to expand knowledge of how karst aquifers respond to changes in precipitation and recharge. Using a 12-year record (2007-2019) of precipitation and three cave drip measuring stations in James Cave (Pulaski Co., VA), we are conducting time-series analyses, including recession and autocorrelation analysis to: 1) quantify the storage volume of the epikarst and 2) examine daily, seasonal and annual trends in the datasets. Results of the recession analysis of the drip hydrographs show spatial heterogeneity in recession coefficients, with lower values at drip sites 1 and 2 (0.49-1.04) and higher values (1.66-2.09) at drip site 3. These results suggest that the location within the cave has an impact on both epikarst storage and drip rates. Autocorrelation analysis will be used to investigate the seasonality and non-seasonality of the 12 year time series of drip data. Results of this study will provide insight into the impact of changes in precipitation patterns on overall recharge to the study aquifer.