Coastal regions across the United States are beset with increasing flood hazards arising from stronger and more frequent storms, sea-level rise, tidal fluctuations, and the compounding effects when these natural and climate-driven hazards coincide. A team of UGA experts led by Dr. Matthew Bilskie and Lina Cardenas Caro, working through the UGA Defense Community Resilience Program, are developing a new rapid risk assessment methodology that can be used to better understand the flood risks to transportation infrastructure, taking into account social vulnerabilities of the local population. The methodology is designed to produce maps that clearly depict geographic areas and specific roadways that deserve transportation planners’ attention.

Rapid risk assessment results, showing “high,” “intermediate,” and “low” flood risk: on the left, across the entire study area;  and on the right, for only the main roads.

The goal of this project is to support transportation planners in their efforts to enhance local climate resilience. For decades, engineers have designed roads, bridges, culverts, and other transportation infrastructure to withstand and recover from stressors, and now they are being asked to also factor in climate-related hazards and social vulnerability metrics. The Infrastructure Investment and Jobs Act of 2021, for instance, made three major changes to federal law that were designed to promote climate resilience in transportation planning – it established the PROTECT program, amended key provisions of the National Highway Performance Program, and expanded the possible uses of the Surface Transportation Block Grant program to include natural infrastructure designed to enhance resiliency.

In this report, we focus on the area surrounding Fort Stewart and Hunter Army Airfield, located near Savannah, Georgia. The study area is primarily in Georgia’s coastal plain, where the topography and hydrology present notable challenges for ensuring roads remain passable in spite of coastal storms and other flood events. The presence of Fort Stewart and Hunter Army Airfield raises an interesting set of issues, as well. The complex is a major “power projection platform,” meaning that it operates under a requirement that significant numbers of personnel and equipment must be able to move out to anywhere in the world on a moment’s notice. Meanwhile, Savannah is a major (and growing) international deep-water port, tourist destination, and logistics hub for the southeast region. Climate-resilient transportation planning is vital to the area both now and into the future.

Read our report, here, for a more detailed discussion of these issues. The report begins with an overview of the issues, describing flood hazards in coastal Georgia and the communities at risk. It then provides an overview of the legal and policy framework governing transportation system planning, highlighting how that regime is being modernized to better incorporate climate and social vulnerability analyses. Finally, the report describes the rapid risk assessment methodology that Bilskie and Caro are developing, with sample maps that they have developed.

Going forward, we have plans to use additional sources of information to improve our risk assessment. For example, we are exploring how we might use information available through the US Army Corps of Engineers’ South Atlantic Coastal Study (SACS) to increase the accuracy of our flood hazard variable. FEMA’s maps have been criticized for being developed based on historical data, without adequate consideration of how global climate change might affect future flooding. The SACS data, by contrast, provide flood extent and depth information based on a variety of future climate scenarios for coastal flooding. With the use of new data from SACS and other sources, we aim to refine our hazard maps for compound flooding (i.e., riverine plus coastal flood hazards) in the areas surrounding Fort Stewart/HAA in ways that will help improve the urban planning for further road and housing design. We also plan to expand our methodology to incorporate hydrodynamic compound modeling for the transition zone (riverine-coastal flood) and assess how the implementation of nature-based solutions might enhance mobility and quality life. For instance, green stormwater infrastructure might improve infiltration, reduce pluvial flooding, and also provide aesthetic benefits or mitigate urban heat island effects. Marsh restoration could reduce the extent of coastal flooding while also providing recreational benefits. New modeling will allow us to test these hypotheses.

Project Team

Matthew V. Bilskie, Assistant Professor, UGA College of Engineering

Lina Cardenas Caro, Graduate Research Assistant, UGA College of Engineering

J. Scott Pippin, Associate Director of Policy and Planning, UGA Institute for Resilient Infrastructure Systems

Matthew Shudtz, Law and Policy Fellow, UGA Institute for Resilient Infrastructure Systems

Project Support

This project is supported by the Network for Engineering With Nature (www.n-ewn.org) and the University of Georgia’s Defense Community Resilience Program in the Carl Vinson Institute of Government. It was supported by the Army Corps of Engineers Awards W912HZ-21-2-0041 and W912HZ-23-2-0018.