A rip current, commonly referred to simply as a rip, or by the misnomer rip tide, is a strong channel of water flowing seaward from near the shore, typically through the surf line. Typical flow is at 0.5 metres per second (1–2 feet per second), and can be as fast as 2.5 metres per second (8 feet per second). They can move to different locations on a beach break, up to tens of metres (a few hundred feet) a day. They can occur at any beach with breaking waves, including oceans, seas, and large lakes.
Causes and occurrence
When wind and waves push water toward the shore, that water is often forced sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea or open lake water. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. A common misconception is that ordinary undertow or even rip currents are strong enough to pull someone under the surface of the water; in reality the current is strongest at the surface. This strong surface flow tends to dampen incoming waves, leading to the illusion of a particularly calm part of the sea, which may possibly lure some swimmers into the area. The off-shore path taken by a rip current can be demonstrated by placing colored dye at the start of a current at the shoreline.
Rip currents are a source of danger for people in ocean and lake surf. They can be extremely dangerous, dragging swimmers away from the beach. Death by drowning comes following exhaustion while fighting the river or ocean current. Varying topography makes some beaches more likely to have rip currents; a few are notorious.
Based on these observations, Rip Current properties can be determined by :
1. Seeing the wave height difference between left and right and else. Wave height on the and right greather than them.
2. Placing objects that can float. If the objects is dragged into the off shore at this site are Rip Current.
3. Seeing water turbidity occurs, where the water in the surf zone is mixed with water from the ground. If the water looks cloudy heading off shore, then where are the Rip Current. This incident can be seen clearly from higher place.
Efforts should be made when dragged rip currents, are as follows:
1. If caught in a rip dragged out to sea, do not try to swim against the current (to the beach),
2. Settle down for a while with the flow. As quickly as the flow drag outside the barrier, or the flow velocity slows down and we feel a little freedom from the rapid movement of water,
3. Swim to the area on the left / right of us and then swam back towards the beach (or follow the waves to the beach). Of course we must keep to stay out of the flow drag.
Oleh : Pebri Nurhayati Mahasiswa Pendidikan Geografi UNY
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