2021-2022 Darcy Lecture
Dr. Alicia Wilson
Alicia Wilson is a professor of hydrogeology in the School of the School of the Earth, Ocean, and Environment at the University of South Carolina. She specializes in coastal hydrogeology, with a particular focus on coastal ecohydrology and submarine groundwater exchange. A fellow of the Geological Society of America, Wilson has served as the chair the GSA Hydrogeology Division and the Director of the School of the Earth, Ocean, and Environment. She is a recipient of the University of South Carolina’s Mungo Undergraduate Teaching Award. Wilson holds a Ph.D. from the Johns Hopkins University, an MS from Stanford University, and a BA from Dartmouth College. She held a National Research Council Postdoctoral Research fellowship at the USGS in Reston, VA, and held a postdoc at the University of California, Santa Barbara.
Wilson Will Present One of the Following Two Lectures at Participating Venues in 2021-2022
Lecture 1: Subseafloor Hydrogeology: Moving beyond watersheds
The field of submarine groundwater discharge (SGD) was launched in the 1990s by the remarkable discovery, via naturally-occurring isotopic tracers, that saline groundwater was discharging to the South Atlantic Bight in very large volumes. Subsequent studies confirmed that saline groundwater discharges to the Atlantic Ocean in volumes that rival river discharge. All available evidence indicates that this saline groundwater is highly enriched in nutrients compared to river water, so the nutrient contributions of this submarine discharge exceed that of river discharge. These findings have been slow to find widespread acceptance, however, because it has been exceedingly difficult to confirm this flow by means other than the original isotropic tracers. This discharge does not occur near the shoreline, and no conceptual models for SGD far from shore existed.
This changed recently when new studies using heat as a tracer identified clear pulses of groundwater discharge 10-15 km offshore in the South Atlantic Bight. This talk investigates this 20-year mystery and the recent discoveries that suggest that it may be time to rewrite chemical budgets for the coastal ocean.
Lecture 2: “Please check your assumptions at the coastline: 15 years of wading through salt marshes”
The field of hydrogeology is well known for its roots in water supply and contaminant remediation, but hydrogeologists are a highly adaptable group who can make critical contributions to -- and learn from -- a wide range of other fields. This talk describes 15 years of progress in understanding the ecohydrology of salt marshes, including everything from how to construct a well in a setting where water levels rise and fall by meters every day to the influence of groundwater flow on plant zonation and carbon cycling. Current research in salt marsh ecohydrology reaches in multiple directions, including the importance of crab burrows for solute and gas exchange in the root zone, the impact of stressors like drought and sea level rise on salt marsh migration, and the role of salt marshes as buffers for development. Carbon budgets for salt marshes are another area of continuing research. Future research will bring improved knowledge of biogeochemical cycling in salt marshes and has the potential to bring advanced ecohydrologic models that address salt marsh migration and restoration as well as atmospheric exchange.
Salt marshes are highly productive ecosystems that form, under the right circumstances, at the land-sea interface. In this zone, they provide buffering against waves, support recreation and fisheries, and influence nutrient and carbon cycling. Groundwater flow through these environments is complex and plays a vital role in the cycling of carbon and nutrients and in influencing the composition and organization of the plants that colonize salt marshes.
This talk will focus on the hydrogeology of salt marshes, through early idealized models and through the much more complex conceptual models.
Groundwater flow through coastal wetlands influences coastal ecosystems in multiple ways. More than a decade of hydrologic field experience at multiple coastal wetland sites in the Southeastern United States has yielded practical methods for field monitoring, as well as new scientific insights into (1) groundwater controls on wetland productivity and zonation; (2) significant variability in submarine groundwater discharge (SGD); and (3) the potential for intertidal wetlands to function as buffers for coastal development. Examples come from salt marshes, the temperate neighbors of tropical mangrove forests. Results have implications for coastal wetland management in the presence of coastal development and sea level rise.