ANALYSIS OF SHIP-INDUCED WAVES ON TYBEE ISLAND WITH RECOMMENDATIONS FOR MITIGATION STRATEGIES

Abstract

Tybee Island’s North Beach experiences hazardous wakes caused by passing container ships travelling to and from the Port of Savannah. 300-foot cargo ships travel at speeds of up to 14 knots on their way from the port, located 23 miles up the Savannah River. News reports of these wake events from Tybee, GA residents detail occurrences of receding of the water, followed by a sudden surge, strong enough to endanger beachgoers. To better understand the effect of port traffic on wave activity, several site evaluations were conducted. Pressure data were collected to evaluate variables that effect water level displacement. The results of these site visits suggest that wake events contain 10 times more energy than wind waves. Ships leaving the port were connected to wake events with an average wave height of 0.55 ± 0.32 meters and an average period of 102.5 ± 21.1 seconds. Several scenarios were analyzed to establish a wave mitigation strategy. After testing multiple algorithms, the solutions were finalized to these four: (1) expanding the current warning system, (2) rehabilitating the existing jetty, (3) the construction of a living shoreline, and (4) the installation of a wave attenuation device