Every year, rip currents kill more people than hurricanes, fires and sharks. Yet a serious disconnect exists between rip current research, identification, human behavior and warnings.
Rip currents are the result of complex interactions between waves, currents, beach slope, wind speed and direction, tides and nearshore bottom topography. A rip current forms as the narrow, fast-moving section of water travels in an offshore direction, usually in a channel between two sand bars.
Sometimes rip currents are caused by human-engineered structures such as groynes, jetties and piers. These structures often are responsible for disrupting the natural flow of water by directing water seaward at an accelerated rate. At these are locations, permanent and extremely strong rip currents occur.
The strength and speed of rip currents varies greatly. This makes them especially dangerous to inexperienced swimmers such as tourists. Typically, rip currents range in velocity between 1 and 3 feet per second. However, recently one of us encountered a rip current in Thailand during monsoon season with a velocity of 8 feet per second.
To demonstrate the danger of a rip current, an Olympic gold medal swimmer was placed in the center of a particularly strong rip current. He was not able to swim against the current despite his world-record swimming ability. This experiment demonstrated the importance of teaching people about the need to swim parallel to the beach until the current weakens before attempting to swim back to shore. If this recommendation is not followed, it may lead to exhaustion, panic and, in some cases, death.
One interesting observation that is beginning to emerge from our research has to do with the relationship between drowning and the strength of the rip current. Intuitively, we expected to find that more drownings occur during times when rip currents are the strongest. Not so. On days when there are strong rip currents, high winds and large waves usually occur. These conditions discourage most beach-goers from swimming.
When the waves and surf begin to abate, swimmers often are lulled into a false sense of safety, not realizing that rips are still present, but not necessarily as strong.
These relatively weak rip currents produce enough strength to pull an unsuspecting individual out to sea. In these more moderate conditions, most drownings seem to occur.
Some of our research involves using tracer dyes to better define the physical characteristics of rip currents. To gain a perfect vantage point, we sometimes hover over the beach in a helicopter. This research is revealing some unexpected results that may suggest the need to rethink some of the education and warning programs currently being devoted to rips.
Most rip currents we observe do not conform to the characteristics portrayed in warnings and that are presented in public education programs. Typically, the classic rip current is depicted — perfectly formed, having an identifiable feeder and neck nearshore that develops into a head or mushroom-like feature further offshore.
In reality, this depiction is seldom valid. In the majority of cases, rip currents cannot be observed from the beach and, in cases when they can be observed, they assume many different configurations.
This observation has important bearing on lifeguard practices. It’s usually not enough for lifeguards to visually look for rip currents from the vantage point of their beach chairs or from standing at the water’s edge.
Instead, they must physically go into the water on a regular basis and “feel” for rips. This should become common practice and be included in all lifeguard manuals.
An interesting outcome of our study is the realization that beachgoers’ knowledge about rip currents significantly varies geographically. For example, beachgoers know more about rip currents on Australian and California beaches than those on Florida and Puerto Rican beaches. The reason for this finding is fairly obvious: There are more tourists on Florida and Puerto Rican beaches, meaning more people unfamiliar with the region or its rip currents.
Our survey is revealing another important finding. About half of the beachgoing public confuses rip currents with rip tides and undertows. Rip tides represent an entirely different phenomenon and, as most savvy experts know, there is no such creature as an undertow!
Though our study won’t be completed for at least another two years, we’ve become aware of a serious disconnect between rip current research and human behavior as it relates to awareness and having accurate knowledge about rip currents.
Our research also is indicating a need to develop better and more consistent warning signs. Despite what many experts believe, warning flags sometimes are not effective in how they warn swimmers about rip currents for the following two reasons: First, flags sometimes are not changed in a timely manner to accurately reflect water conditions. Secondly, because flags represent symbolic language, people don’t always know what a flag means. The public is especially confused about the meaning of a “red” flag and a “double red” flag.
This information underscores the importance of disseminating information that allows for the correct interpretation of the flag colors. It also underscores the importance of consistent flag use on different beaches. This must be done on beaches throughout the world, not just in America.
Better and more effective rip current warnings should be developed. But until this can happen, the ones currently in use (that is, the flags) should be continued because something is much better than nothing, especially on unguarded beaches. Vacationers staying at hotels, for example, still should be warned using flags and condition boards.