Hammock groundwater modeling Dr. Christof Meile University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

cmeile@uga.edu http://www.marsci.uga.edu/directory/christof-meile https://orcid.org/0000-0002-0825-4596 Dr. Samantha B. Joye University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

mjoye@uga.edu http://www.marsci.uga.edu/directory/samantha-b-joye Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Christof Meile University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

cmeile@uga.edu http://www.marsci.uga.edu/directory/christof-meile https://orcid.org/0000-0002-0825-4596 Principal investigator Dr. Samantha B. Joye University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

mjoye@uga.edu http://www.marsci.uga.edu/directory/samantha-b-joye Principal investigator Dr. Alicia M. Wilson University of South Carolina

Department of Geological Sciences University of South Carolina Columbia South Carolina 29208 USA

awilson@geol.sc.edu https://sc.edu/study/colleges_schools/artsandsciences/earth_ocean_and_environment/our_people/directory/wilson_alicia.php https://orcid.org/0000-0002-1113-6267 Co-investigator Dr. Willard S. Moore University of South Carolina

Department of Geological Sciences University of South Carolina Columbia South Carolina 29208 USA

moore@geol.sc.edu http://www.geol.sc.edu/billy.htm Co-investigator 2026

The observations collected on groundwater nutrients, flow, and radium isotopes as part of the intensive hammock characterization will form the core data set for calibration and validation of water balance models for each hammock. Large scale shallow subsurface flow patterns between hammock and creeks will be established by building upon available finite element codes. Measured hydraulic head and permeability measurements will be spatially interpolated. Together with infiltration/evapotranspiration rate estimates they will be employed to assess water movement using a Darcy approximation and water continuity. Given the uncertainty in driving forces and observed heterogeneity in marsh soil hydraulic conductivities, model simulations will be validated by the radium based water balance. Water fluxes to and from marsh soils will be assessed following Gardner and Reeves (2002). Vertically resolved fluid transport estimates will be validated using temperature profiles.

Area 3: Responses to Salinity and Inundation (more information) Question 4: What are the underlying mechanisms by which proximity of marshes to upland habitat drives ecosystem change along lateral gradients in the intertidal zone? (more information)

LTER NSF Georgia GCE flow groundwater isotopes nutrients Overall geographic extent of the research project -81.295506 -81.195661 31.546868 31.395295 2010-01-01

National Science Foundation grant numbers OCE-9982133 and OCE-0620959

estuary marsh complex Hunt Camp - Barrier island/marsh site on western Sapelo Island. This site is located at the upper reaches of the Duplin River, and is within the Sapelo Island National Estuarine Research Reserve. Existing well fields border small marsh area to northwest, some wells have been installed to south end of hammock where marsh is more extensive and permanent plots are located. Two existing hydrographic sondes and weather stations within this site are operated by SINERR (Hunt Camp dock) and UGAMI (flume dock). -81.295506 -81.258908 31.497026 31.462320 North Sapelo - High salinity marsh/Sapelo Sound site. Few or no small creeks, but one large creek is easily accessed. Further upstream upland drainage is affected by culvert at Reynolds' duck pond. Upland is heavily forested. Hydrographic sonde is deployed adjacent to this site attached to a channel marker (under U.S. Coast Guard permit). A huge mud flat is present at the northern tip of Sapelo Island. -81.233249 -81.195661 31.546868 31.515188 UGA Marine Institute - The University of Georgia Marine Institute is located on the southern end of Sapelo Island, a barrier island off the central Georgia coast. -81.282950 -81.278834 31.398877 31.395295 Miklesh, D.M., McKnight, C.J., Di Iorio, D. and Meile, C. 2015. Poster: Controls on porewater salinity distributions in a southeastern salt marsh. LTER All Scientists Meeting, Aug 30-Sept 2, Estes Park, CO. Ledoux, J.G., Alexander, C.R. Jr. and Meile, C. 2015. Poster: Groundwater flow at the Georgia coast: Magnitude and drivers across a back barrier island – marsh transect. LTER All Scientists Meeting, Aug 30-Sept 2, Estes Park, CO. Ledoux, J.G. 2015. Drivers of groundwater flow at a back barrier island - marsh transect in coastal Georgia. M.S. Thesis. The University of Georgia, Athens. 104 pages. Ledoux, J.G., Alexander, C.R. Jr. and Meile, C. 2014. Poster: Delineating groundwater flow along a marsh transect at a back barrier island on the coast of Georgia. Southeastern Estuarine Research Society Fall meeting, November 6-8, Carolina Beach, NC. Porubsky, W.P., Joye, S.B., Moore, W.S., Tuncay, K. and Meile, C. 2011. Field measurements and modeling of groundwater flow and biogeochemistry at Moses Hammock, a backbarrier island on the Georgia coast. Biogeochemistry. 104:69-90. (DOI: 10.1007/s10533-010-9484-8) http://www.springerlink.com/content/t18x02358tt6x123/ Meile, C., Porubsky, W.P., Walker, R.L. and Payne, K. 2009. Natural Attenuation Of Nitrogen Loading From Septic Effluents: Spatial And Environmental Controls. Water Research. 44(5):1399-1408. (DOI: 10.1016/j.watres.2009.11.019) Porubsky, W.P. and Meile, C. 2009. Controls on groundwater nutrient mitigation: Natural attenuation of nitrogen loading from septic effluents. In: Hatcher, K.J. (editor). Proceedings of the Georgia Water Resources Conference. Athens, Georgia. HYD-GCES-1401b - Groundwater well pressure, temperature, conductance, salinity and oxygen measurements for GCE-LTER study hammock PC_i_29 from 15-Aug-2008 to 13-Dec-2013 https://gce-lter.marsci.uga.edu/public/app/dataset_details.asp?id=567 HYD-GCES-1401a - Groundwater well pressure, temperature, conductance, salinity and oxygen measurements for GCE-LTER study hammock HN_i_1 from 30-Oct-2008 to 03-Dec-2013 https://gce-lter.marsci.uga.edu/public/app/dataset_details.asp?id=566 POR-GCES-1401 - High frequency sediment surface temperature measurements at GCE-LTER study hammock PC_i_29 from 15-Aug-2008 to 24-Sep-2012 https://gce-lter.marsci.uga.edu/public/app/dataset_details.asp?id=568 Conceptual model of flow across the upland/marsh interface, showing arrangement of wells and piezometers. Bottom left: View of large scale subsurface flow model domain showing salt/freshwater interface (color transition) and flow paths. Bottom right: Site-specific schematic showing interactions between soil and plant models, including water flow and nutrient cycling. https://gce-lter.marsci.uga.edu/public/resources/projects/groundwaterQ4.png