Rip currents

Forecast alerts for rip currents will soon be given by Indian National Centre for Ocean Information Services (INCOIS) and the Indian Space Research Organisation (ISRO) under a new initiative.

• The focus is on enhancing beach safety through a coastal video surveillance system, providing crucial information on complex coastal and nearshore processes.

What are Rip currents?

• Rip currents are powerful, narrow channels of fast-moving water that flow from near the shore to the deeper ocean or sea.
• They are a natural and common coastal phenomenon, typically occurring at beaches with breaking waves.
• Rip currents can pose dangers to swimmers and are a leading cause of beach-related incidents.
• These are prevalent along the East, Gulf, and West coasts of the U.S., as well as along the shores of the Great Lakes.

Causes and Occurrence:

Wave Action:

• Rip currents often form when waves approach the shore at an angle.
• As waves break and water rushes towards the shore, it accumulates in the form of “run-up” or “wave setup.”
• This excess water then seeks a path of least resistance to flow back seaward, creating a concentrated and narrow current.

Sandbars and Underwater Features:

• The presence of sandbars, channels, and other underwater topographic features greatly influences the formation of rip currents.
• The water flowing onto the shore during wave action tends to follow the deeper channels, creating concentrated flow paths seaward.
• The breaks in sandbars can act as channels for the water to flow back out to sea, forming rip currents.

Tidal and Wind Effects:

• Tidal patterns and wind direction can also impact the development of rip currents.
• For example, during low tide, the presence of sandbars and deeper channels becomes more pronounced, increasing the likelihood of rip current formation.
• Wind can influence the strength and direction of the currents as well.

Characteristics:

• Formation: Rip currents form when waves break near the shore, causing water to accumulate near the coastline.
  • This excess water then returns seaward in concentrated channels, creating a narrow, fast-flowing current.
• Appearance: While rip currents are not always easily visible, some signs include differences in water color, choppier and foamier water, or debris moving seaward.
• Strength and Speed: Rip currents can be very powerful, with speeds that can exceed 5 miles per hour (8 km/h).
  • This is faster than most people can swim.
• Narrow and Focused: Rip currents are typically narrow, ranging from about 10 to 100 feet (3 to 30 meters) in width.
  • They can extend from the shoreline beyond the breaking waves.
• Pulling Effect: The primary danger of rip currents is their ability to pull swimmers away from the shore and into deeper water.

Ref: Source