Warning signs not enough to keep beachgoers out of deadly currents

Keeping people away from rip currents is more about looking at human behaviour than warning signs . Every year rip currents cause hundreds of drownings worldwide and tens of thousands of rescue needs. With 85% of Australia’s population living within an hour’s drive of the coast, rip currents kill more people than floods, cyclones and shark attacks combined. In 1938, Sydney’s most popular beach, Bondi Beach, had the infamous rip current tragedy: within minutes, about 200 swimmers were swept away by the rip current, leaving 35 unconscious and five dead. More commonly, however, rip currents take one life at a time with little media attention. For many beachgoers, casualties from rip currents go unnoticed. While three-quarters of beachgoers say they know what rip current is, only 54 percent define it correctly. Only half of those surveyed remembered seeing a warning sign posted at or near the main entrance to each beach or a bunting sign indicating surfing conditions. Fewer recalled the colors of the bunting – green for calm seas, yellow for moderate conditions and red for dangerous situations.

Part of the challenge of preventing rip current-related drownings is the lack of an easy way to avoid them. Rip currents form when waves pile up seawater near the shoreline. Seawater flows back to the sea following the path of least resistance. It may flow along channels between sandbars or next to solid structures such as piers or rocky headlands. These types of rip currents can persist year after year. Other rip currents are more unstable, briefly bursting into the ocean on flat, open beaches. Rip currents are often mistaken for waves receding from shore or “rip tides”. Rip currents, however, are not caused by tides, the waves that recede from the shore are a different, weaker current that is created as water that is pushed onto the beach leaves the shore along the seabed. Ripple churning, sandy water, or black flat gaps between breaking waves are all clear signs of rip current.

For decades, beach safety experts have had an oversimplified view of rip current mechanisms, so it’s no surprise that the public misunderstands them. In some of the earliest studies of rip currents in the mid-20th century, American scientists observed sticks, kelp fragments and volleyballs floating into the sea, and described flowing waterways extending more than 300 meters from the coast. The work lays the groundwork for the popular view that rip currents are rapids that blast waves outward perpendicular to the coast. To avoid rip currents, experts advise swimmers to swim parallel to the coast – a practice that has been advertised in the US and Australia through educational campaigns and warning signs. As it turns out, this approach may not always work.

This article is reprinted from: https://www.solidot.org/story?sid=71849
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