Flood Vulnerability for Transportation Infrastructure in Chatham County, GA

Sea level rise and more intense precipitation due to climate change are among some of the biggest concerns along the Georgia coast. These concerns, and their associated flood risks, can have negative impacts on transportation networks and the lifespans of road infrastructure. With the coastal Mid-Atlantic region of the United States having some of the highest rates of relative sea level rise (RSLR) globally due to land subsidence and other contributing factors, it is important to outline vulnerable points of concern for flood events. The Georgia Department of Natural Resources’ Coastal Resources Division (CRD) derived multiple potential projected sea level rise scenarios for the coastline: a conservative low projection and a high SLR projection for the years 2050, 2075, and 2100. Using ADCIRC, a dynamic tidal model was employed for each of these SLR scenarios, and the peak water elevations for each tidal pattern within Chatham County were recorded. To determine the risk of flooding from precipitation events, water elevations were pulled from the US Army Corps of Engineers’ South Atlantic Coastal Study (SACS) for storms of the 1% Annual Exceedance Principle (AEP) and the 0.2% AEP. The data from both methods were used to create water surface rasters within Chatham County, Georgia. Using a LiDAR-created DEM and a Chatham County road segment shapefile, elevations were assigned to each segment at their risk from each flood and storm event was determined.