Context:
Recently, High Sea waves which are also known as swell waves (is called swell surge or Kallakkadal), have flooded numerous houses in the Kerala’s coastal areas.
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Hundreds of residences in various coastal zones of Kerala have experienced flooding.
- This flooding caused by the swell waves is called swell surge or Kallakkadal in Malayalam.
- Alappuzha, Kollam, and Thiruvananthapuram districts are among the hardest-hit areas.
Indian National Centre for Ocean Information Services (INCOIS) in 2020 launched an early warning system called the Swell Surge Forecast System.
- INCOIS usually gives a 7-day advanced warning.
- It has alerted people in coastal areas vulnerable to sea erosion to take precautionary steps and ensure the safety of fishing vessels.
What is Kallakkadal?
- It is a geographical phenomenon which causes flooding through high waves, during the pre-monsoon season (April-May) along India’s south-west coast.
- The expression ‘Kallakkadal,’ coined by local fishermen is a fusion of two Malayalam words which is ‘Kallan’ denoting thief, and ‘Kadal,‘representing sea. When Comined together, the words ‘Kallakkadal’ signify ocean that arrives as a thief.
- The term was formally approved by UNESCO in 2012.
Factors behind Kallakkadal
- Kallakkadal is caused by waves generated by ocean swells hence known as swell surge.
- Unlike local winds ocean swells originate from distant storms such as hurricanes or prolonged periods of intense gale winds.
- These storms transfer significant energy from the air to the water leading to the formation of exceptionally high waves.
- These waves can traverse vast distances from the storm’s center until they reach the coastline.
- Typically, Kallakkadal results from strong winds in the southern Indian Ocean where ocean swells are created and these waves then propagate northward reaching the coast within two to three days.
- It occurs spontaneously without any precursor or local wind activity.
How Kallakkadal different from tsunami?
- Kallakkadal is caused by waves generated by ocean swells or hurricanes.
- On the other hand, tsunami which is a series of enormous waves due to seismic activity like earthquakes, underwater landslides or volcanic eruptions.