MAPPING GROUNDWATER VULNERABILITY TO CLIMATE CHANGE IN KIAWAH ISLAND, SC

The integrity of terrestrial ecosystems on barrier islands are dependent on the thickness of the fresh groundwater lens and groundwater salinity. Seawater surrounding the island infiltrates the sub-surface and displaces freshwater from the aquifer into a thin layer within the vadose zone. Typically, freshwater is more abundant toward the middle of the island, the shape of the lens is influenced by the geomorphology and distribution of geologic materials of the island and on Kiawah Island multiple man-made ponds. Saltwater inundation during storms, king-tide events, and sea level rise causes saltwater to slowly infiltrate and threaten the quality of groundwater. These conditions could potentially lead to the degradation of both the maritime forests and the built infrastructure thru repeated exposure to salt water.

The project team began installing wells on January 16, to date 16 monitoring wells have been installed across Kiawah Island. Several water table wells are instrumented with automated dataloggers collecting water level and salinity data at 30-minute intervals, and all wells are monitored manually on a weekly basis. The team gathers temperature (T), depth (L), and conductivity (C) measurements. Using groundwater flow direction modeling and GIS mapping the team is creating an understanding of surface and groundwater movement through the watershed.

Studying the groundwater and mapping Kiawah’s freshwater lens will provide crucial information about the current and potential conditions of such saltwater intrusion and provide better insight into the perceived impacts on the ecosystems of the island. Monitoring these fluctuations over time could help provide information about siting for green-infrastructure projects (e.g., rain gardens and bioretention areas), implementation of Low Impact Development (LID) practices, and restoration projects to improve the island’s resilience to flooding while enhancing the diminishing freshwater lens.