CREATING A GIS OF CAROLINA BAY DISTRIBUTION IN SOUTHEASTERN GEORGIA, USA

Carolina bay wetlands are elliptically shaped depressions with a variety of land cover types from thickly-vegetated wetland forests to open water ponds. These depressions typically have a NW/SE long-axis orientation, and can range in diameter from <100 m to more than 1 km. Although Carolina bays are an important habitat supporting unique ecological systems, regional management of these resources is limited by the lack of detailed maps or GIS databases of bay distribution and attributes.

Mapping the bays is not an easy task. Mapped contours do not always correlate well with bay depressions, missing some of the more shallow depressions entirely. Wetland and soils databases do not always distinguish between Carolina bays and other wetland types. Bay identification from remotely-sensed imagery is also complicated by the great variability in landcover of different bays and by human alterations to bays. Due to these mapping complications, precise criteria were defined for what wetlands to map as bays.

The goal of our current research is to create a geographic information system of Carolina bay distribution in three Georgia counties: Chatham, Effingham, and Screven. We used a ESRI ArcMap to compile various data layers including Landsat imagery, orthophotography, color infrared aerial photos, National Wetlands Inventory data, and geologic data to aid in the mapping process. The resulting GIS will provide a useful management tool for monitoring and managing these wetlands in Georgia. The GIS will also be a starting point for addressing questions that surround the bays such as: Are there spatial patterns to location of the Carolina Bays? Are there correlations between underlying geology and bay placement, size, orientation, or number of sand rims? The results for this three-county area will provide a guideline for mapping bay distribution on other parts of the coastal plain.