USING MULTIPLE METHODS TO EVALUATE LANDWARD MIGRATION OF SEAWATER INTRUSION IN THE FLORIDAN AQUIFER

The Floridan aquifer of the Southeast U.S. is an important freshwater resource for private and commercial groundwater users. Within the past few decades, certain parts of the aquifer have experienced saltwater intrusion. Groundwater withdrawals, variability in recharge and discharge rates, and sea level rise have caused saltwater to advance into this and other coastal aquifers. While the South Carolina Department of Natural Resources (SC DNR) has an ongoing program to monitor the water conditions in several Floridan aquifer wells, a comprehensive hydrochemical saltwater intrusion study of the aquifer in the Berkeley-Charleston-Dorchester region of South Carolina had not been conducted since the publication of a SC DNR report in 1985. The current SC DNR and College of Charleston project goal was to inspect the water quality in Floridan aquifer wells in the tri-county region to determine the extent of saltwater intrusion. The objectives of this project were to analyze well water samples and map the location of the freshwater-saltwater interface. Specific conductance of the well water and chloride concentrations are typical indicators of saltwater intrusion, but signal chemical elements (strontium, bromide and boron) were also measured in the water samples to provide more nuanced intrusion information. Ongoing work includes spatial statistical analysis of the water chemistry data in the more than six dozen wells studied in this area. Statistical correlations between the chemical elements are being used to develop a model of saltwater intrusion. Information on the properties and conditions of the Floridan aquifer is in high demand for many stakeholders, including municipalities, agricultural operations, industrial activities, and natural resource managers who depend on a stable source of groundwater as public and private water supplies.