Groundwater Dynamics in Georgia's Coastal Ecosystem

Several research scientists, graduate students and undergraduate students have recently participated in a large ongoing National Science Foundation Long Term Ecological Research (LTER) study at Sapelo Island, Ga.  The role of CCU’s Burroughs & Chapin Center for Marine and Wetland Studies in this project is to better understand groundwater processes in the tidally controlled Duplin River and surrounding estuary.  Principal investigators Rick Peterson and Rich Viso make field trips to Sapelo Island at least once a year to collect geochemical and geophysical data designed to quantify and image groundwater systems.  These data help physical modelers, ecologists and biologists from other institutions understand processes such as marsh tidal inundation, effects of sea level rise, biological zonation and marsh erosion.  In prior years, technical staff from the Center have also generated detailed bathymetric maps of the Duplin River system, revealing the shape of the sea bed and lending insight into the processes forming the river channel.

During field operations, CCU scientists travel to Darien, Ga. where they launch a boat and load their scientific gear and personal luggage for the trip to the remote Sapelo Island.  Some of the science team may also ride the ferry that shuttles Sapelo’s few residents between the island and the mainland.  With very little infrastructure and no stores or restaurants on the island, scientists must plan accordingly with provisions to last the duration of the trip.  There are some basic dormatory facilities and vehicles available for travel around the island at the University of Georgia Marine Institute, located on Sapelo.

Once on the island, the science team unloads their luggage at the dorms and heads straight out to the river to begin deploying equipment that measures temperature, salinity and water level of surface and groundwaters.  In addition, wells are installed for groundwater sampling and measurements of the electrical structure of shallow marine and upland sediments are made throughout tidal cycles.  Under the direction of Rick Peterson, radon measurements are conducted in order to determine variability in groundwater discharge to the Duplin.

Preliminary results suggest the salinity structure of the upper few kilometers of the Duplin is largely controlled by groundwater inputs.  The river is entirely contained within a salt marsh, and there is no source of upland recharge other than through the ground along the shorelines of Sapelo Island and the surrounding marsh.  This has many important implications for understanding the geological evolution of the marsh and the biological assemblages that live within.

This study has been an amazing opportunity for those involved.  There are over 20 principal investigators from a variety of universities including University of Georgia, University of Florida, University of South Carolina, Georgia Tech, Creighton University, Ohio State University, and Skidaway Institue of Oceanography among others.  Financial support for the CCU’s involvement comes from NSF and, in addition to supporting scientific efforts, provides support for students to participate in the field work and data reduction.  The students always seem to enjoy spending the week working at Sapelo.  Undergraduates are inspired as they engage in first hand application of theories learned in the classroom setting.  Graduate students broaden their backgrounds by helping with logistics and application of methods in field areas other than those of their own studies.  One former CCU undergraduate, Jon Ledoux, has benefited directly from involvement in this project as he was recruited for graduate studies at the University of Georgia.

Finally, students who participate in the field studies have the opportunity to travel to Athens, Ga. the following January and participate in the annual meeting for the entire study group.  This meeting is typically attended by 40-50 principal investigators, technicians, students and other interested parties.  Members of the CCU team prepare and deliver oral and poster presentations during the two day meeting.  This year, two graduate students, Sarah Chappel and Leigha Peterson, will attend the meeting and present results from data collected during the first week of April 2012.

Please direct further questions or comments to Rich Viso (; 843-349-4033).