Kallakkadal

• 04 Apr 2024

Source: IE

Why in News?

Recently, hundreds of houses have been flooded in several coastal areas of Kerala due to high sea waves named Kallakkadal.

• Lakshadweep and Tamil Nadu coast are other areas often affected by Kallakkadal.

What is Kallakkadal?

• About:
  • Kallakkadal refers to coastal flooding caused by swell waves during the pre-monsoon season (April-May) and sometimes during post monsoon along the southwest coast of India.
  • The term Kallakkadal, used by local fishermen, is a combination of two Malayalam words, including Kallan and Kadal. “Kallan means thief and Kadal means sea, meaning “ocean that arrives as a thief.
• Causes:
  • It is caused by waves formed by ocean swells, which originate from distant storms such as hurricanes or prolonged periods of intense gale winds (usually in the southern part of the Indian Ocean).
  • These storms transfer significant energy from the air into the water, resulting in the formation of extremely high waves.
    • These waves can travel vast distances from the storm center until they reach the shoreline.
  • Kallakkadal occurs without precursors or any kind of local wind activity and as a result, it has been very difficult for the coastal population to get an advance warning.
  • However, early warning systems like the Swell Surge Forecast System —launched by the Indian National Centre for Ocean Information Services (INCOIS) in 2020 gives forewarning seven days in advance.

Why is Kallakkadal Different from Tsunami?

• Kallakkadal came under the spotlight after the 2004 tsunami and is often mistaken for a tsunami. However, a tsunami is a series of enormous waves created by an underwater disturbance, usually associated with earthquakes occurring below or near the ocean.
  • Ocean waves (like Kallakkadal) have a wavelength of only 30 or 40 meters, tsunamis have a very long wavelength often hundreds of kilometers long.

Indian National Centre for Ocean Information Services (INCOIS)

• INCOIS is an autonomous organisation under the Ministry of Earth Sciences (MoES).
  • It is located in Hyderabad & was established in 1999.
  • It is a unit of the Earth System Science Organization (ESSO), New Delhi.
• It is mandated to provide the best possible ocean information and advisory services to society, industry, government agencies and the scientific community through sustained ocean observations and constant improvement through systematic and focused research.

UPSC Civil Services Examination, Previous Year Question (PYQ)

Prelims:

Q 1. Consider the following statements: (2020)

1. Jet streams occur in the Northern Hemisphere only.
2. Only some cyclones develop an eye.
3. The temperature inside the eye of a cyclone is nearly 10ºC lesser than that of the surroundings.

Which of the statements given above is/are correct?

(a) 1 only 
(b) 2 and 3 only 
(c) 2 only
(d) 1 and 3 only

Ans: C

Q. At one of the places in India, if you stand on the seashore and watch the sea, you will find that the sea water recedes from the shore line a few kilometres and comes back to the shore, twice a day, and you can actually walk on the sea floor when the water recedes. This unique phenomenon is seen at (2017):

(a) Bhavnagar
(b) Bheemunipatnam 
(c) Chandipur
(d) Nagapattinam

Ans: C