We are advancing coastal dune and marsh modeling of the barrier islands, estuary and interior marshes in the Mississippi Sound to evaluate trade-offs between coastal management strategies and proposed restoration efforts in the region.

Why We Care
Rising seas are damaging coastal habitats in Mississippi and Alabama and increasing flood risk to coastal communities. The beaches and dunes on our coastal barrier islands are being eroded away, and coastal marshes are drowning and in need of coastal restoration activities. There are more activities needed than can be accomplished, requiring approaches to evaluate proposed projects. We are particularly responding to the management community’s interest in assistance for prioritizing restoration on the barrier islands compared to the interior marshes in the Mississippi Sound.

What We Are Doing
The goals of the proposal are to (1) enhance modeling of sediment transport and barrier island evolution to include dynamic models of tides, storm surge, and marsh productivity; (2) model the physical processes and feedbacks between the offshore barrier islands, estuary and marsh; and (3) evaluate the effects of local restoration scenarios on mitigating inundation and share a probabilistic analysis of trade-offs to inform decision-making. All of this work will be done in coordination with a management advisory group, which includes many individuals that served on an existing advisory group for a prior ESLR award.

The modeling advancements will be based upon an existing coupled framework linking the Delft3D, XBeach and Empirical Dune Growth (EDGR) models for decadal-scale simulations of barrier island evolution and sediment transport during quiescent conditions, storm events and post-storm recovery. However, modeling framework will be extended to incorporate existing dynamic models of tides, waves and storm surge (SWAN+ADCIRC), and marsh productivity (Hydro-MEM). This advancement will permit simulations of the interactions and feedbacks between the offshore barrier islands, estuary and marsh under varying scenarios of storminess, sea level rise, and restoration alternatives, in a more advanced way than has been possible.

Benefits of Our Work
Expected outcomes of this project include: (1) enhanced integrated modeling framework for regional decadal-scale simulations of morphology, hydrodynamics and marsh productivity that can be used for ecosystem service assessments under scenarios of SLR, storminess and restoration alternatives; (2) improved scientific knowledge of the function of offshore barrier islands and interactions and feedbacks with the estuary and marsh and (3) user driven tools or information that will provide guidance on the value of regional versus local restoration alternatives that can be used for managing the barrier islands and adjacent mainland coast.

The project is led by the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center and includes co-investigators from the U.S. Geological Survey Wetland and Aquatic Research Center, Louisiana State University Center for Coastal Resiliency and the University of Georgia School of Environmental, Civil, Agricultural and Mechanical Engineering. The project is funded through the NCCOS Effects of Sea Level Rise Program.