DELINEATION OF RESERVOIRS WITHIN KARST AQUIFERS UTILIZING THERMAL DATA

The use of thermal data has become a novel way of exploring groundwater movement. Within karst systems, the interconnectedness of surface water and groundwater suggests that temperature may be an important parameter in delineating flow components within an aquifer. To assess the utility of temperature data in determining flow in karst systems, thermal signatures from seven wells and six springs were analyzed. Temperature signals were used to determine potential relationships among different storage reservoirs and the air temperature. From the temperature data, three distinct reservoirs: epikarst, shallow groundwater, and deep groundwater, were identified. The reservoirs have different thermal signatures and relationships with the air temperature. During a wetter period, the epikarst water temperatures more closely follow the air temperature trend and are closer in value, but during drier conditions, the shallow groundwater temperatures are more similar in value to air temperature. Deep groundwater temperatures show no relationship to variations in surface air temperature. Using the water temperatures from the three reservoirs, the sources of water at two major springs, Copperhead and Langle, were delineated. During the wetter period, the shallow groundwater and the epikarst were the primary contributors of water to the springs. As conditions became drier a transition occurred, the deep groundwater became the major source of water to the springs. Variation in temperatures of waters at Copperhead and Langle spring are a result of the epikarst and the shallow groundwater, which represent ineffective thermal reservoirs.