BEAUFORT ADAPTS: SEA LEVEL RISE IMPACTS ON GROUNDWATER AND SEPTIC SYSTEMS IN BEAUFORT, SC

Beaufort County Adapts brought together scientists, residents, and decision-makers to prepare for impacts of sea-level rise on local groundwater and infrastructure in Beaufort County, South Carolina. The Project was designed to develop science-based maps and tools to identify infrastructure and social services that are vulnerable to sea-level change in order to develop actionable timelines for proactive decision-making across the county. The project team is a collaboration between the College of Charleston, University of South Carolina, the South Carolina Sea Grant Consortium, and the Beaufort County, SC planning and watershed management departments.

Focusing on septic systems this project developed maps of present day and future depth to groundwater surfaces at a parcel scale. These high-resolution groundwater maps were found to match baseline groundwater elevations to within 0.5 meters across the county. Maps of properties with septic systems were developed for the county and the types of septic systems used across the county were identified. Using 1.5 years of well data, baseline GW elevations and rain event GW elevations were used to develop formulas for the number of expected days of impairment for the various types of septic systems. Maps were made for three time horizons 2024, 2050, 2100 allowing parcels with likely impaired septic systems to be identified in each time horizon.

This project demonstrates the power of topographically constrained groundwater models for developing high resolution depth to groundwater surfaces at county-wide scales. Combining these surfaces with rainfall information as well as well data and monitoring with an understanding of the depth of sensitive buried structures, the number of days that these systems could be compromised was calculated. This has allowed the county government to begin to take direct action and plan for future actions due to sea levels rise. The techniques developed in this project are transferable to other coastal counties across United States.