Rip Currents
Rip currents are powerful, channeled currents of water that flow offshore from beaches. These dangerous currents are the most serious hazard that threatens bather safety on the world’s surf beaches. In the United States, more people drown in rips annually
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Rip Currents Stephen P. Leatherman
Abstract Rip currents are powerful, channeled currents of water that flow offshore from beaches. These dangerous currents are the most serious hazard that threatens bather safety on the world’s surf beaches. In the United States, more people drown in rips annually than are killed by hurricanes, tornadoes or lightning. Florida has the highest loss of life because of its long shoreline and warm waters, followed by other popular states for ocean swimming with many beaches—California and North Carolina. In response to these safety concerns, the science of rip currents has advanced significantly in the past decade. The First International Rip Current Symposium was held in Miami, Florida in 2010 where research advancements through field investigations and modeling were highlighted. These insights are being used to promote more effective public education and develop innovative outreach programs and tools.
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Introduction
Rip currents (rips) are a major coastal hazard, but they receive far less attention than most other coastal hazards; this is largely because rips do not affect houses or infrastructure and relatively few people are lost during each event. Approximately 100 U.S. beachgoers drown annually in these powerful currents (Fig. 26.1). Eighty percent of all lifeguard rescues are the result of rips, which amounts to more than 50,000 people pulled out of the water each year with some requiring medical treatment and hospitalization (www.usla.org). Rip currents are a problem worldwide with other known hot spots being Brazil, Australia and Israel (Short and Hogan 1994; Leatherman and Fletemeyer 2011).
S.P. Leatherman (*) Laboratory for Coastal Research and Department of Earth & Environment, Florida International University, Miami, FL 33199, USA e-mail: [email protected] C.W. Finkl (ed.), Coastal Hazards, Coastal Research Library 6, 811 DOI 10.1007/978-94-007-5234-4_26, # Springer Science+Business Media Dordrecht 2013
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S.P. Leatherman
Fig. 26.1 Rip currents cause more deaths on average than lightning, tornados or hurricanes (not counting Hurricane Katrina in 2005) according to the National Weather Service
Rip currents are fairly common on surf (e.g., breaking wave) beaches along oceanic coasts, including the U.S. Atlantic, Pacific and Gulf Coasts as well as the Great Lakes. Beaches are the number one recreational destination for Americans; this fact coupled with the relatively high occurrence of rips and limited knowledge and experience of many beachgoers accounts for the large number of drownings and rescues. These seaward-flowing currents are deceptively dangerous; they sometimes appear as calm water between the whitewater of the breaking waves, and hence appear to be safer places to swim (Leatherman 2003). These “rivers in the sea” originate in shallow water (Fig. 26.2). The principal driving force is longshore variation in wave height, which is affected by many factors, such as bathymetry and spatially-varying wave fields (Haller et al. 2002; Wright and Short 1984;
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