Danger From Beneath: Groundwater-Sea-Level Interactions and Implications for Coastal Archaeological Sites in the Southeast US

Coastal low-lying archaeological sites are known to be at risk due to sea-level rise associated with climate change. However, not all of the potential impacts of sea-level rise on these sites have been documented. In this interdisciplinary study we set out to document the effects of rising groundwater tables induced by rising sea level on middens located on barrier islands in southeastern Florida. After excavating two sites, we collected sediment samples that were analyzed for grain size and moisture content. We found that even though these sites are not yet submerged below the groundwater table significant increases in moisture content indicate a subterranean source of the moisture, most likely the capillary fringe above the water table. Increased moisture content of the sediment in which the artifacts are entrained can increase artifact deterioration. Therefore, current and future groundwater water table elevations should be considered when prioritizing sites for excavation and preservation.