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Source-This post on Kallakkadal: A phenomenon leading to floods in Kerala is based on the article “What is Kallakkadal, which has flooded houses in Kerala’s coastal areas?” published in “The Indian Express” on 3rd April 2024.
Why in the News?
Recently, numerous homes in Kerala’s coastal regions have been flooded due to high sea waves, which are referred to as swell waves. These flooding incidents are termed swell surge or Kallakkadal in Malayalam.
What is Kallakkadal?
1. 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.
2. Meaning:
a. The term “Kallakkadal,” coined by local fishermen, combines two Malayalam words: “Kallan,” meaning thief, and “Kadal,” meaning sea. When spoken, these words were combined as “Kallakkadal,” signifying the sea arriving like a thief.
b. In 2012, UNESCO formally approved this term.
What causes Kallakkadal?
1. Ocean swell and distant storms:
a. It is caused by waves formed by ocean swells, which originate from distant storms such as hurricanes or prolonged periods of intense gale winds.
b. These storms transfer significant energy from the air into the water, resulting in the formation of extremely high waves.
c. These waves can travel vast distances from the storm centre until they reach the shoreline.
2. Formation– Typically, Kallakkadal occurs due to strong winds in the southern Indian Ocean, where ocean swells are generated. These waves then travel northward, taking around two to three days to reach the coastline.
Challenges in its Preparedness
1. Kallakkadal happens suddenly without local wind activity, making it hard for coastal residents to receive advance notice.
2. Yet, systems like the Swell Surge Forecast System, initiated by the Indian National Centre for Ocean Information Services (INCOIS) in 2020, provide a seven-day warning.
How it is different from Tsunami?
| Kallakkadal | Tsunami |
| Kallakkadal is a sudden flash flood event that happens without any apparent change in local winds. | A tsunami is a massive wave series caused by underwater disturbances. |
| It is caused by strong winds. | It is caused by earthquakes. |
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