Dangerous Currents: Don’t Get Swept Away

Dave Benjamin Dec 26 2010 160It was the day after Christmas 2010. Dave Benjamin, a Great Lakes surfer, was winter surfing on Lake Michigan with some friends when he got into trouble. The leash to his surfboard failed, and he was out in the water, getting hit by wave after wave and was caught in a current. Water had breached his wetsuit. He was losing energy.

“I have been swimming in Lake Michigan all of my life,” said Benjamin. “All of that experience went out the window when panic set in. I came to a point where I was writing myself off. I came to the resolution that I’m not going home today.”

This lesson explores dangerous currents, including rip currents that commonly occur throughout the Great Lakes.

Grade Level: 9-12th grades

Performance Expectations:

  • HS-PS4.1 Waves and Their Applications in Technologies for Information Transfer: Use mathematical representations to support a claim regarding relationships among the frequency, wavelength and speed of waves traveling in various media.
  • HS-ESS3.1 Earth and Human Activity: Construct an explanation based on evidence for how availability of natural resources, occurrence of natural hazards and changes in climate have influenced human activity.
  • MS-ESS2-2 Earth’s Systems: Construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at varying time and spatial scales.
  • MS-ESS3-2 Earth and Human Activity: Analyze and interpret data on natural hazards to forecast future catastrophic events and inform the development of technologies to mitigate their effects.

For alignment, see: NGSS Summary

Lesson Objectives

  • Learn about the different types of dangerous currents and where they occur.
  • Understand who is most at risk.
  • Analyze data about rescues and deaths related to dangerous currents.
  • Explain actions that will help prevent drowning.

 

Background

Dave Benjamin with surf boardWhile Dave Benjamin’s story may not resonate at first — he was surfing in December, after all — it has all of the elements of a warmer-weather drowning, including exhaustion and panic after getting caught up in a current. Something he learned before he got in the water saved his life.

And getting caught in a dangerous current in the Great Lakes happens more than you might think — to strong swimmers and water novices alike. Since 2002, there have been more than 130 deaths and about 300 rescues directly attributed to currents in the Great Lakes.

These are conservative numbers — it is likely that currents contribute to many more deaths and rescues in the Great Lakes than are reported. Many of the deaths happened near structures, like piers and breakwalls, making these areas the most hazardous places.

Dave Benjamin was near a breakwall when he got into trouble in Lake Michigan. He was losing energy.

“I was very close to the break wall, but I knew immediately that I couldn’t use it as an escape because it was jagged rocks covered in ice,” he said. “The waves were smashing my board into the wall and I feared that I would be next to get smashed into the wall.”

Dangerous Currents breakwall Dec 26 2010 150He was reviewing his life, he said, when an article about drowning came back to him. It was then he did what saved his life: essentially nothing. He stopped struggling against the current, flipped over and began to float on his back, which gave him time to catch his breath and think. He was eventually able to make it back to shore, taking turns resting and swimming. He flipped, floated and followed his way to safety.

Want to read more about real people encountering dangerous currents?
Check out:
http://www.nws.noaa.gov/ripcurrents/real_life.shtml

To learn more about the science behind dangerous currents, see: Dangerous Currents 101 Lesson

Characteristics

When examining past current-related incidents, there are several factors that may play a part, including the following:

  • Wind is most likely toward the shore, at 25 mph or less.
  • The most commonly observed wave height range was 3 to 4 feet. This is likely because this is the range of wave heights that most people feel comfortable swimming in, and it is the start of when rip current speeds become dangerous. However, 5 to 6 foot wave heights were also common.
  • The most common weather pattern observed during rip current incidents was the passage of a cold front. This is to be expected, as cold fronts are frequently accompanied by high winds and waves, which are more supportive of rip current development.

Wave Heights

Wave Periods

Number of Incidents

 (Source: National Weather Service – Marquette Office)

Can You Tell if There’s Danger Lurking?

Strong winds can change quickly and produce severe conditions on any of the Great Lakes — severe enough to sink even large ships. For example, some wave heights can reach more than 23 feet (7 meters). Such extreme events cause waves so high, most people know to stay out of the water. But what if the waves are 3 to 5 feet tall? While the lower waves may seem more inviting, they can often relate to areas where dangerous currents may be present.

 

Rip currents and other dangerous currents often form in or near the "surf zone" which typically is where people are swimming.

Rip currents and other dangerous currents often form in or near the “surf zone,” which  is where people typically swim.

As seen in the image to the right (provided by Guy Meadows, a rip current researcher based at Michigan Technological University), currents happen in what is called the “surf zone.” They can also show up when the waves are not too high, 3-4 feet, but approaching the shore quickly. Currents in the Great Lakes can be particularly treacherous because Great Lakes storms and waves can build with alarming speed, giving a swimmer in trouble less time to recover between waves.

Signs of Rip Currents:

  • Low spots along the shore, can often be found near river mouths
  • A break in the incoming wave pattern
  • A channel of churning, choppy water
  • A line of foam or debris moving seaward
  • A difference in water color

Some beaches have a sign system to signal when the conditions may be ripe for dangerous currents. Yet, every year, people die because they ignored warnings, like yellow or red warning flags and water safety signs. Please pay attention to the signs!

 

Who’s at Risk?

The short answer: You are.
The longer answer: Any swimmer can get caught in a current. However, according to National Weather Service statistics, a high percentage of the rescues and fatalities involved young males (aged 24 and under). Of the 21 rescues and recoveries that took place in 2013, 11 were for males, while 7 were females and 3 the sex was not reported.

Since 2002, more than 430 incidents directly related to dangerous currents have been collected. An estimated 47 percent of those incidents included males, while only 22 percent included females and in 31 percent of the incidents, the sex of the victim was not reported.

Research has shown that younger males may be more at risk because of their involvement in higher-risk situations and the influence of peer pressure, like jumping off of piers and breakwalls. Structures present multiple hazards, like rocks and persistent currents that often prevent swimmers from reaching safety.

While younger males may be at the top of the risk pyramid, other statistics stand out as well. For example, many of the rescues and fatalities can be older adults, who have gone in the water to help save a child. Children are also at risk. This can be further explored in the activity below: Who is Drowning in the Great Lakes?

What Happens?

People drown when they are unable to keep themselves afloat and get to safety or wait for help. Often a combination of fear, panic, exhaustion and lack of swimming skills contribute to death or near drownings. However, as noted at the beginning of this lesson, even experienced swimmers can get into trouble, depending on the conditions at the time.

 

ACTIVITIES

Summary: Using Great Lakes incident statistics from the National Weather Service, students use real data to research rescues and deaths in the Great Lakes.

Time: One 50-minute class period

 

Summary: Students explore and discuss how to recognize the signs of drowning and how to help someone else.

Time: One 50-minute class period

 

Lesson Sources

  • Michigan Technological University, Guy Meadows
  • National Weather Service, Marquette Office, Megan Dodson and Keith Cooley
  • Great Lake Surf Rescue, Bob Pratt and Dave Benjamin
  • Michigan Department of Environmental Quality, Matt Warner and Rhonda Wycheck
  • Michigan Department of Natural Resources, Mike Evanoff

 

Resources