A GIS BASED APPROACH TO COASTAL RISK MAPPING IN GEORGIA

Coastal Georgia contains a combination of barrier islands, broad mezotidal estuaries, wetlands, maritime forests, hummocks, forested uplands, and large rivers. Georgia’s six coastal counties are often subjected to tropical and extratropical storm systems, as well as storm-induced flooding and surges. With rapidly increasing populations, coastal managers increasingly need sound scientific data on which to base decisions on zoning, planning, and property damage mitigation. Coastal risk maps provide such a tool.

Risk maps for McIntosh and Camden counties were created using ArcInfo and ArcView geographic information software. The final risk map represents the union of three established hazard layers: (1) vegetation from satellite imagery, (2) FEMA digital Q3 flood zone maps, and (3) SLOSH model maps of potential storm surge from the U.S. Army Corp of Engineers. Each layer consists of a numerical value assigned to attributes of each polygon according to potential risk. The three layers are then merged together to produce one final risk map with the creation of new polygons that contain the sum values of each hazard layer. A ranking of low, moderate, high, or extreme risk is given to each polygon based on an established range. Fieldwork was conducted at selected sites on each map to check the validity of the risk category assigned to that area. The risk maps along with a site description, risk assessment checklist, and photographs were submitted to coastal managers of each county as part of a FEMA-sponsored Project Impact partnership between the Coastal Georgia Regional Development Center and the State University of West Georgia.