Rip currents: researching a natural hazard - Hodder Education Magazines

Researching a natural hazard

Rip currents (often incorrectly referred to as rip tides) are a serious hazard for sea bathers. This article describes new research carried out by the authors, in partnership with the RNLI, to better understand the nature of rip currents. It explains why the currents occur, why they are so hazardous, and how the results of the research can be used to help protect the public from risk. If you are studying coasts or natural hazards — or if you swim in the sea — you should read this article

Gerd Masselink, Martin Austin, Tim Scott and Paul Russell

Have you ever wondered how beach lifeguards decide where to place their red and yellow flags to indicate safe-swimming areas? On sandy beaches with large waves there are often sand bars (shallower areas) under the water (Photograph 1). Deeper channels between these bars either run along the beach or cut across the sand bars. The complicated shape of the bars and channels, referred to as the bar/channel morphology, causes complicated wave refraction patterns.

Strong currents can be present in the channels and when the flow is away from the beach, towards the sea, these currents are called rip currents. Flow velocities in rip currents often exceed the speed at which people can swim and can easily drag unsuspecting swimmers out to sea. So beach lifeguards place their flags away from rip currents and near the shallow sand bars where bathing is safest.