Project travels up estuaries to find tipping points

Department of geography researchers are collaborating with faculty from the Warnell School of Forestry & Natural Resources and the College of Agriculture and Environmental Sciences on a four-year project supported by a grant from NOAA to connect marsh health with local economics and environmental impact. Our colleagues in the Warnell School report:

The forces at work in a marsh require a delicate balancing act.

Rising and falling tidewaters keep clumps of Spartina grasses from growing too dense. But too much water makes it difficult for them to survive. Tip this balance too far in either direction and the marsh ecosystem collapses, resulting in a population of different plants—or no plants at all.

We know a lot about this process in salt marshes. But as you travel farther away from the shore, venturing into brackish and even freshwater marshes, there’s less we know about how these systems stay healthy. Now, a new grant will help University of Georgia scientists delve into the dynamics of these wetlands, including how collapsing marshes can affect property values and storm resiliency in coastal communities.

“We’re taking an existing mathematical model that’s out there for salt marshes and moving it up into brackish and freshwater marshes, which have different vegetation and different soils,” said Lori Sutter, research scientist at the University of Georgia Warnell School of Forestry and Natural Resources and principal investigator on a new four-year, $1.5 million grant from the National Oceanic and Atmospheric Administration. “And, we want to use what we know about how long a marsh will be able to stay at a high enough vertical space to keep up with sea-level rise.”

The project is one of five new projects across the country aimed at addressing the complex challenges of sea level rise. The full list of projects is available online.

Using a biophysical feedback model, the Marsh Equilibrium Model, Sutter and colleagues from University of South Carolina and Villanova University will be able to more realistically predict interactions between soil, plants and water level in tidal marshes. Those results will be incorporated into a flooding model called the Sea Level Affecting Marshes Model, or SLAMM, which the team will apply to marsh areas in Georgia, South Carolina and the Delaware Bay. Once they determine wetland areas that will likely flood, the team will incorporate various scenarios of rising sea levels.

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Image: Saltwater estuary, courtesy of USGS.