WIND VELOCITY INFLUENCE ON ENHANCED TIDAL FLOODING ON LITTLE CUMBERLAND ISLAND, GEORGIA

Little Cumberland Island (LCI) is one of the many barrier islands along the Georgia coast. LCI is privately owned and managed by a homeowner association whose covenants require that the island remain as natural as reasonably possible. With no bridge connection to the mainland, a single small dock serves as the only access to the island. Additionally, all roads are constructed from local sediment, which makes many of the low-elevation roads very susceptible to tidal flooding and erosion. When there is extreme tidal flooding, residents cannot navigate the roads nor leave the island. Residents have reported a connection between stronger wind speeds and more extreme tidal flooding; this study sets out to quantify the relationship between wind velocity and enhanced tidal flooding due to wind set up. Tidal-elevation data were recorded using seven HOBO pressure sensors deployed throughout the island along the most flood-prone roads, including at the dock. Enhanced tidal flooding was calculated by differentiating the recorded tidal elevations from those predicted by NOAA, which do not consider wind set up. A multiple linear regression was performed and three-dimensional scatter plots were created to quantify and visualize the impact of wind velocity on tidal flooding. Surprisingly, results indicate that wind measured by NOAA buoy 41008, which is 70 km offshore, is a better indicator of enhanced tidal flooding than wind measured onshore within 15 km of LCI. Results validate residents’ reports that strong wind velocity, above 15 mph, in the direction of greatest fetch can enhance tidal flooding by tens of centimeters. These conclusions will allow island residents to predict event-scale flooding and more effectively manage their roads.