What is a rip current?
A rip current is a powerful, narrow channel of fast-moving water that flows away from the shore, like a river flowing out of the sea. Rip currents are usually 10 to 30 feet wide but can extend much farther. Their speed can range from 1 to 3 feet per second. In some cases, they can even reach speeds up to 8 feet per second, faster than Olympic swimmers.
A common myth of rip current:
Rip currents will pull swimmers down, but this is not true. The strongest and fastest flow occurs beneath the water's surface, and friction reduces force near the bottom.
How do rip currents form?
Rip currents can form at the shores of the ocean, sea, or lakes whenever wind and breaking waves bring surface water toward coastal areas. The water level near the shores rises, and water escapes back to the open sea, choosing the path with the least resistance, creating a rapid current.
Common types of rip currents:
Channelised rip currents:
The most common rips are channelised rips. Channelized rips form when irregular morphology, such as sand bars or channels, is near the shore. A break in the relatively shallow sand bars allows water to flow offshore with the least resistance, creating the rip current.
Channelized rips can last days, weeks, or even months. Rips with the signature "dark gap" flowing offshore are the easiest to spot, indicating the rapid current.
Boundary rip currents:
Natural and artificial structures such as headlands, reefs, piers, or jetties that project out to the sea can form permanent boundary rips. Boundary rips happen when the waves approach the shore at an angle, creating a flow along the coast, meeting obstacles, and deflecting away into the sea. Most of the boundary rips also appear as a "dark gap."
Flash rip currents:
Flash rips form without relating to the morphology and structures near the shores. When random large waves or multiple large waves break in, causing a rapid rise in water level, resulting in turbulent or strong offshore flow (flash rips).
Flash rips are considered dangerous as they form suddenly and rapidly without prediction. They can appear in one beach area but quickly disappear and form again in other location. They occur without a "dark gap" and resemble turbulence or sandy water heading away from the coast.
Does it happen only in bad weather?
Rip currents do not necessarily happen during bad weather. They can emerge on a nice sunny day after a storm. However, strong winds can trigger powerful rip currents. A significant storm hundreds of miles away from the coastline can produce large swells and rip currents. The threat is more significant when the storm is 1-2 days away from landfall.
Hazards to swimmers:
It is one of the most dangerous hazards in coastal swimming, causing 80% of beach rescues or more than 100 fatalities annually in the USA. A study has shown rips lead to more accidents than cyclones, floods, bushfires, and shark attacks combined in Australia.
How to spot a rip current:
It can be challenging to spot a rip current, but there are some tips for you:
It is easier to observe from a higher ground.
Notice any break in the wave patterns; the water may look flat compared to breaking waves on both sides.
A foam/ debris river: when the current brings foam and debris away from shore.
Different color/dark gap: A dark gap may appear in channelized / boundary rips. Depending on the sun's angle, spot any darker or lighter band of water compared to the surroundings.
Look for the turbulent channels, churning or choppy water.
Before you engage in outdoor water activities:
Check the weather forecast: notice if a storm is approaching or leaving.
Choose a beach with lifeguard services and check for warning flags.
Ask people with local knowledge about the beach area.
Be a better swimmer, swim with floatation, and have a water activities buddy.
What to do if You encounter a rip current:
Stay calm to conserve your energy.
Don't swim against it: rips are strong currents, and trying to swim against them can exhaust you.
Swim parallel to shore: swim sideways/ perpendicular to the currents until you are free, then swim back to shore at an angle.
If you can't progress, float or tread water to conserve energy and signal for help by waving your arms or shouting.
Identifying and responding to rip currents can significantly increase your safety while enjoying the beach. When possible, always swim in designated areas with lifeguards.
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