Physical controls of circulation and residence time in the Altamaha River estuary

The Altamaha estuary is a dynamic and complex ecosystem that connects three adjacent sounds (Altamaha, Doboy and Sapelo Sounds) with the South Atlantic Bight. These environments are constantly changing with mixing of freshwater from uplands and saltwater brought into the estuary primarily by tides and wind forcing. To investigate circulation in the estuary, we use the Delft3D-Flow multidimensional coastal hydrodynamic and transport model with inputs of tides, winds and river discharge as forcing on a structured, boundary fitted grid. Using the Delft3D-Flow model over a 15-month period from December 2016 - February 2018, we implemented a tracer tracking technique to investigate transport processes and provide a quantitative estimate of residence times within the Altamaha estuarine domain. Model simulations of temperature and salinity compared favorably with the continuous temperature and salinity dataset from the Georgia Coastal Ecosystems Long Term Ecological Research hydrographic moorings. We present estimates of transport pathways of freshwater and residence time in the estuary and quantify how those vary seasonally in response to variations in forcing. Our results inform on spatiotemporal variations and distribution of nutrients, contaminants, and other tracers in the estuarine domain and is relevant to several ecological processes.

Presentation Preference: Either

Primary Presenter: Mitchelle Agonsi, University of Georgia (mitchelle.agonsi@uga.edu)

Authors:

Mitchelle Agonsi, University of Georgia  (mitchelle.agonsi@uga.edu)

Renato Castelao, University of Georgia  (castelao@uga.edu)

Joan Sheldon, University of Georgia  (jsheldon@uga.edu)