We are assessing the impacts of sea level rise and coastal storms on marshes and oyster habitats in the northern Gulf of Mexico through the development of predictive models that coastal zone managers may use for long-term planning. This large-scale research study includes the panhandle of Florida, coastal Alabama, and coastal Mississippi, and the tools developed will provide enhanced certainty in scale and local detail.

Why We Care
The northern Gulf of Mexico coast benefits economically from a wealth of natural resources that depend on healthy coastal ecosystems. However, these ecosystems face a number of threats, including sea level rise and hurricanes. The impacts of sea level rise could be dramatic. Low-lying coastal areas are expected to experience:

• increased levels of flooding,
• accelerated erosion,
• loss of wetlands and low-lying terrestrial ecosystems, and
• seawater intrusion into freshwater sources.

Rising sea level and erosion will also imperil critical habitats for many commercially important fisheries that depend on inshore waters for either permanent residence or nursery area.

Coastal management agencies struggle to balance the pressures of coastal development with the conservation and protection of the coastal environment. Increased hurricane activity and rising sea levels already threaten shoreline habitats, as well as productive wetlands that are prevalent in the Gulf of Mexico. Tools that provide predictive capabilities will enable smart management of coastal systems, improve targeting of restoration efforts, and facilitate planning.

What We Are Doing
This project will provide predictive tools to determine the impact of sea level rise on coasts and coastal habitats and will transition the resulting information to management applications. The study area includes three National Estuarine Environmental Research Reserves: Apalachicola, FL, Weeks Bay, AL, and Grand Bay, MS. Field and laboratory experiments as well as resulting ecological models will focus on these reserves, but will also apply to coastal habitats throughout the region.

The five-year project is improving and applying existing models of circulation, sediment transport, and biogeochemistry from the watershed to the sea, including waves and erosion. The ultimate prediction will be sediment loadings to the estuary as a result of overland flow, shoreline and barrier island erosion, and salinity transport in numerous bay systems, all of which will be used to model the evolution of intertidal marshes and oyster habitats. These models will make use of existing bathymetric and topographic data and related data sets. Field and laboratory experiments will provide the information needed to determine parameters for the marsh and oyster habitat models. The project is also assessing impacts in the presence of simulated and retrospective tropical storms.

To facilitate applications to the coastal management community, the project also funds a diverse management committee. This committee, consisting of federal, state, and local managers as well as conservation organizations, provides guidance to the science team on required information needs and project tool development. Prior to funding, this project was planned and approved both within NOAA and across the Gulf of Mexico (including the Gulf of Mexico Alliance) to ensure relevant science needs would be addressed.

The project team included partners from NOAA/NCCOS, Louisiana State University, the University of Central Florida, the University of Florida, Florida State University, the University of South Carolina, Grand Bay National Estuarine Research Reserve, and Dewberry, Inc. Collaboration and significant assistance has also been provided by NOAA's National Geodetic Survey and NOAA's Coastal Services Center.

Benefits of Our Work
Improving the predictive understanding of ecosystem responses to sea level rise and increasing storm surge allows coastal zone managers to more effectively assess alternative management strategies for mitigating future ecological and socioeconomic impacts of climate change. The management community will be able to:

• prioritize risk management strategies,
• identify restoration locations that can be sustained over the long term,
• reformulate set-back requirements,
• improve guidelines for construction of breakwaters and other coastal infrastructure, and
• assess water resource impacts and protection needs.

This project will yield several useful products, including: maps that delineate new tidal boundaries as a result of sea level rise; estimates of sediment loadings from overland runoff to estuarine systems, and erosion rates; projections of changes in critical habitats (e.g., salinity distributions, marsh, beach, shellfish, submerged aquatic vegetation, land cover), and water resource impacts. These products will facilitate a comprehensive, forward-looking assessment of coastal ecosystem change in response to sea level rise that is not possible with current tools. This project is also serving as the foundation for the Gulf of Mexico Sentinel Site Cooperative.

What We’ve Accomplished
The Apalachee Regional Planning Council integrated future surge more accurately into strategic planning documents. The National Estuarine Research Reserve in Apalachicola, FL used the Marsh Story Map to understand the potential to utilize thin layer sediment placement of dredged sediments to bolster failing marshes and to understand the natural storm surge protection provided by St. George Island and how it could change under increased sea level. Apalachicola (FL) used floodplain results for historical building adaptation. Magnolia Springs (MS) is using storm surge results for a feasibility assessment. Jackson County (MS) used storm surge data to protect wastewater treatment facilities against flooding. Santa Rosa County (FL) is using floodplain results for a Vulnerability Assessment. The U.S. Air Force used floodplain results to identify bases across the study area at risk to future flooding and to inform development planning. Two Story Maps, developed in part by NCCOS internal scientists, enabled these applications. NCCOS internal scientists conducted value-added analyses in response to stakeholder needs and met with partners listed above to answer questions about the data and provide customized data files. The project led to 57 peer-reviewed publications.

This approach was recognized in the 2014 Department of Transportation hydraulic engineering manual case study as paradigm shifting science for its “systems of systems” approach to coupling process-based models that contain sub-models.