Quantifying the Impact of Recreational and Commercial Usage of the Atlantic Intracoastal Water Way (AIWW) on the Natural Resources of Georgia

Estuaries are ecosystems of major importance biologically and economically. Human activities make estuaries environmentally vulnerable. Although processes like shoreline erosion and accretion are natural, human activities can increase the rate at which these processes take place. The Atlantic Intracoastal Water Way (AIWW) is a man-made estuarine shipping channel that runs from New Jersey to Florida. Wakes created by recreational and commercial vessels represent the major impact to the AIWW shoreline. These wakes cause channel widening and bury living oyster reefs in sediments, causing them to die.

This study focuses on quantifying the impact of anthropogenic modification and boat wakes along the Georgia portion of the AIWW shoreline. Long-term change in the AIWW was assessed used GIS tools to examine decadal-scale shoreline behavior. The data used in this study consist of historical shorelines for the AIWW main channel and alternative routes. All shorelines were digitized in ARCGIS 9.3 using NOAA T-sheets (1860’s and 1933) and aerial imagery (1942, 1972, and 2002-04). Shorelines were analyzed using AMBUR (Analyzing Moving Boundaries Using R). To assess recreational boating impacts, creeks with significant boat traffic (e.g., near marinas or public boat ramps) were digitized and compared to nearby creeks with little boating impact. Dead oyster reefs were identified by their spectral signature for the years of 1942, 1972, and 2002-04.

Within the main AIWW channel, the major shoreline movements are channel dilation and migration with high shoreline change rates. Maximum rates range from -3.00 m/y erosion to 7.62 m/y accretion. The alternate routes present lower shoreline change rates, with rates ranging between -1.49 m/y erosion and 2.48 m/y accretion, which can be attributed to lower boat traffic in these areas. Dead oyster reefs are found along the main channel of the AIWW, while the alternative routes do not exhibit a large quantity of dead oyster bars, also indicating lower boat traffic. Recreational boating activity appears to significantly increase shoreline change rates downstream (toward the next major channel) from marinas and boat ramps.