Rip Currents

Rip currents are responsible for about 150 deaths every year in the United States. In Florida, they kill more people annually than thunderstorms, hurricanes and tornadoes combined. They are the number-one concern for beach lifeguards: About 80 percent of all beach rescues are related to rip currents. Despite these startling statistics, many swimmers don't know anything about rip currents, and they have no idea how to survive when caught in one. In this research paper I will discuss what causes rip currents, how you can recognize them and what you should do if one takes you out to sea (http://science.howstuffworks.com/rip-current.htm). Rip currents can occur at anytime of the year, but the majority of deaths occur from may to august when the combination of large number of bathers and favorable wind conditions coincide (www.ripcurrents.noaa/gov/overviews .shtml). What is a rip current? a rip current is a strong surface current of water flowing out past the surf zone, the surf zone is the area between the high tide level on the beach to the seaward side of breaking waves, where at the height of a rip current it is able to pull the strongest swimmer into the deep water. Rip currents can be found on many surf beaches every day. Rip currents most typically form at low spots or breaks in sandbars, and also near structures such as groins, jetties and piers. Rip currents can occur at any beach with breaking waves, Rip currents can be as narrow as 10 or 20 feet in width but some can be as much as ten times wider. The length of the rip current also varies. Rip currents begin to slow down as they move offshore, beyond the breaking waves, but sometimes extend for hundreds of feet beyond the surf zone ( http://www.ripcurrents.noaa.gov/faq.shtml#form). It can even reach speeds of up to 1m/s and some have been reported as high as 2 m/s. Signs that a rip current is present are very subtle and difficult for the average beachgoer to identify. Look for differences in the water color, water motion, incoming wave shape or breaking point compared to adjacent conditions. Look for any of these clues: such as

* Channel of churning, choppy water

* Area having a notable difference in water color

* Line of foam, seaweed, or debris moving steadily seaward

* Break in the incoming wave pattern

One, all or none of the clues may be visible. (http://www.ripcurrents.noaa.gov/faq.shtml#look). Rip currents have long been an interest to scientists studying waves and beaches, but only in recent years have Sea Grant and National Weather Service research searched for ways to identify the wave and sea conditions that create hazardous rip current velocities and to correlate the conditions with actual rescue data from local lifeguards. What we have learned to date is being used to identify those days when the potential for dangerous rip currents is higher, the Rip Current Outlook for your beach. Researchers around the country are actively searching for better prediction and warning methods (http://www.ripcurrents.noaa.gov/faq.shtml#look). Rip currents affect people's lives as well as the environment Rip currents can cause severe erosion. Rip currents can strip as much as 6.5 feet of elevation off the beach, leaving crescent-shaped embayments (http://www.ecy.wa.gov/programs/sea/coast/waves/ripcurrents.html). Although rip currents can be treacherous, they can be of some importance to the environment also. Rip currents influence the morphology of the shore line and may be important for transporting fine sediments off shore. The understanding of rip currents is important in developing accurate forecasts for predicting "high risk" rip current events that are a public safety. Overall rip currents are produced waves, when waves break, water is pushed up the slope of the shore, gravity then pulls the water back to sea. If it converges in a narrow like current moving away from the shore it forms what is known as a rip current (International Journal of Marine Geology, Geochemistry And Geographics).

There have been research studies done on rip currents to better understand them. One study in particular was done in Gainsville, Florida by two doctoral students. For the study, Dean and Jamie MacMahan, a UF doctoral student in civil and coastal engineering, analyzed thousands of time-elapsed photos of a rip current-prone section of the beach on North Carolina's Outer Banks. Shot hourly for 2Ð... years from a 100-foot tower at a federal research facility, the photos revealed dark swaths of the ocean the researchers tied to rip currents. The swaths expanded or shrank as weather and surf conditions changed, but remained in the same place along the beach even after storms. Rip currents typically occur as water pushed between a sandbar and the beach rushes seaward through a channel in the bar. Dean and MacMahan's research found that these channels persist even as wave action moves the sandbar toward the beach. Only a particularly large storm or hurricane moves the channels, the study found. The study shows that rip currents likely are much more common that had been thought, becoming noticeable, and dangerous, only when the flow of water is sufficient to create a strong current. That tends to occur when storms or particularly strong tides push large amounts of water toward shore, piling water into the gap between the sandbar and beach, Dean said. A strong rip current moves at about three feet per