Ship Forces on the Shoreline of the Savannah Harbor Project

摘要

Ship forces having the potential to cause shoreline erosion were evaluated at Savannah Harbor to compare the without-project (existing) and the with-project (deepened) channels. Comparable ship speeds were determined in the without-project and with-project channels based on field data and an analytical model. Four traffic alternatives were evaluated that primarily differ in the number of post-Panamax ships compared to Panamax ships. At Fort Pulaski, dominant ship effects include short period bow and stern waves and long period drawdown and return velocity. The composite return velocity and drawdown per ship are 3.2 to 6.2 percent less in the with-project channel. Due to the slightly higher speed in the with-project channel, short period bow and stern waves are the shoreline attack force that increases in the with-project channel at Fort Pulaski. The composite short period bow and stern wave height per ship for years 2030 and 2050 is predicted to be 1.5 to 4.4 percent greater in the deepened channel. At Tybee Island, the only significant ship effect reaching the shoreline is the long period drawdown or pressure wave. The composite drawdown in the channel between the jetties per ship is 2.3 to 5.9 percent less in the with-project channel.