Rip Currents

Excerpt

Many of the world’s beaches are characterized by the presence of strong, concentrated seaward flows called rip currents. Rips are an integral component of nearshore cell circulation and ideally consist of two converging longshore feeder currents which meet and turn seawards into a narrow, fast-flowing rip-neck that extends through the surf zone, decelerating and expanding into a rip-head past the line of breakers. The circulation cell is completed by net onshore flow due to mass transport between adjacent rip systems. Rip flows are often, but not always, contained within distinct topographic channels (Figure R18) and can be visually identified by darker streaks through the surf zone due to greater water depths, offshore moving foam/sediment patches, and surface turbulence created by the wave-current interactions. Rips are of great significance to coastal nearshore studies since they provide a major mechanism for the seaward transport of water and sediments, have a pronounced effect on nearshore morphology, aid in the dispersal of pollutants, and represent a major hazard to recreational beach users. It is therefore of some concern that many aspects of rip behavior, generation, and occurrence remain poorly understood. In fact, the term was first used by Shepard (1936) in order to distinguish rip currents from the misnomers rip tide and undertow, which are unfortunately still commonly used to describe rips today.

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