MODELING HURRICANE STORM SURGE INUNDATION RISK TO DEVELOPMENT ALONG THE GEORGIA COAST, USA

Recent hurricanes have generated interest in improved storm surge risk maps along the Georgia coast. Storm surge is defined as flooding due to increased sea level resulting from low atmospheric pressure in the storm center. Risk from storm surge is a function a hurricane’s extent, intensity, tidal stage at landfall, and magnitude of anthropogenic development at low elevations. Tidal stage during hurricane landfall is one of the most critical factors in determining the extent of storm surge risk. Our objective was to map risk to anthropogenic development along the Georgia coast from a 2 m storm surge at a range of tidal stages. A two-meter storm surge was selected based on observed storm surges during Hurricane Matthew (2.1 - 2.3 m, 2016) and Hurricane Irma (1.1 - 1.4 m, 2017). Median high tide and median low tide were calculated based on local NOAA tidal gauges. Anthropogenic development was mapped using 30 m land use / land cover available through the 2011 National Landcover Dataset. Risk maps were generated by modeling potentially inundated elevations and then overlaying developed LULC data.

Initial analysis of Glynn County, GA included a study area of 217,529 ha of which 17,380 ha is developed. Inundation at the low tide interval was 191 ha and inundation at high tide was 7,150 ha. There was a thirty-six-fold increase in developed land at risk during high tide versus low tide. During low-tide only 1.1% of the developed area in Glynn county is at risk of inundation from a hurricane with minimal or moderate storm surge. However, if the same storm surge occurs during high tide, 41% of the developed areas are at risk of inundation. Future research explore additional tidal stages (extreme low and extreme high). Additionally, localized sea level rise predictions will be incorporated into future inundation models.