Rip current hazard on Florida and South Georgia beaches

摘要

Sand bar heights have been shown to vary geographically as related to sand size, beach slope and wave energy. Pen-sacola Beach in the Florida Panhandle has the largest bar height at 0.9 m and this area is anecdotally known as the drowning capital of Florida. Miami Beach in Southeast Florida has a bar height of 0.6 m and the second highest number of drownings in the state. Lido Beach in Southwest Florida has a bar height of only 0.35 m and is characterized by very few drownings with most attributed to tidal currents at Big Sarasota Pass Inlet. The beach at South Cumberland Island is located a few km north of Florida and has a subtle bar with a height of 0.25 m, and there has never been a documented rip current drowning. Time-series beach profile data from the Florida Department of Environmental Protection (2014) and Dean (2010) match these bar height measurements closely. Previous wave tank studies also show a clear relationship between bar height and rip current presence and strength (Leatherman et al. 2013). All of these data indicate that bar height is an important factor in determin- ing rip current hazards on surf beaches. Currently, the National Weather Service rip current forecast does not include local geographic information, which could make their forecasts more accurate.