GROUNDWATER AND SURFACE WATER INTERACTIONS IN AN ACTIVE KARST AREA UNDER DIFFERENT FLOW CONDITIONS, CARTER COUNTY, TENNESSEE

Many karst features such as caves, sinkholes, springs, and losing streams are founded to be connected to the Rock House Cave groundwater system in Cater County, northeastern Tennessee. Preliminary dye-tracing test by students and faculty at East Tennessee State University (ETSU) in September 2005 revealed that groundwater velocity is approximately 400-500 m/day during normal-flow conditions. To further investigate the flow conditions during a severe drought year, Fluorescein and Eosin liquid dyes were injected simultaneously in Dry Creek and Rock House Cave in November, 2008. Both dyes were detected in Cave Spring Cave, which merges into Buffalo Creek. Water samples were collected along cave conduits, surface streams, and springs during the tracing period. Dye analyses of these water samples indicate that this is a highly dendritic conduit flow system. Surface water disappeared from different locations along Dry Creek. No dyes were detected at upstream locations or other springs along Buffalo Creek and dye concentration decreases gradually along downstream locations. It takes more than a month for all the dyes wash into the karst aquifer from the losing stream - Dry Creek, during low-flow conditions. However, once the dye gets into the karst conduit, it would be transferred very rapidly to its outlet, Cave Spring Cave.

During high-flow seasons, Dry Creek remains in the surface channel and merges into Buffalo Creek. Dye tracing was conducted as part of the ETSU’s karst field school activity during May and June of 2009. Rhodamine WT and Fluorescein liquid dyes were introduced at locations along Dry Creek, with one dye injected late and about one mile upstream of the other. Most of the dyes flew through surface channel and into Buffalo Creek. However, both dyes were also detected in Rock House Cave in less than two days, significantly faster than flow velocities from previous tracing test in 2005 and 2008. Results from recent tracing test indicate that high-flow conditions result in more rapid groundwater velocities in this active karst system.