Kallakkadal

Kallakkadal

News: In recent days, numerous residences in various coastal areas of Kerala have been inundated by high sea waves, commonly referred to as swell waves. The most severely impacted districts are Alappuzha, Kollam, and Thiruvananthapuram. These flooding incidents are locally known as swell surge or Kallakkadal in Malayalam..

About:
• Kallakkadal refers to coastal flooding occurring during the pre-monsoon season (April-May) due to swell waves on the southwest coast of India.
• The term originates from Malayalam, a local language, combining two words: Kallan meaning thief and Kadal meaning sea, symbolizing the oceans stealthy intrusion.
• In 2012, the term was officially endorsed by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Formation of Kallakkadal:
• Kallakkadal, or swell surge, is triggered by waves generated by ocean swells, not local winds, often originating from distant storms like hurricanes or prolonged periods of intense gale winds.
• During such storms, significant energy transfer occurs from the atmosphere to the ocean, resulting in the formation of exceptionally high waves.
• These waves can travel vast distances, sometimes thousands of kilometers, until they reach the shoreline.
• Formation of Kallakkadal:
• Kallakkadal emerges as a consequence of the robust winds in the southern Indian Ocean, where ocean swells are generated.
• These waves then propagate northward, reaching the coastline within two to three days.
• The most recent occurrence was observed following the passage of a low-pressure system over the region around March 25, originating approximately 10,000 kilometers off the Indian coast in the South Atlantic Ocean.
• The presence of this pressure system induced strong winds, resulting in the formation of swell waves reaching heights of up to 11 meters.

Challenges: 
• Kallakkadal events occur suddenly without precursors or local wind activity, making it challenging for coastal communities to receive advance warnings.
• Due to the unpredictable nature of Kallakkadal, traditional warning systems often fall short in providing timely alerts to at-risk populations.
• To address this issue, the Indian National Centre for Ocean Information Services (INCOIS) introduced the Swell Surge Forecast System in 2020.
• This system utilizes advanced forecasting techniques to provide early warnings of Kallakkadal events, offering forecasts up to seven days in advance.
• The implementation of the Swell Surge Forecast System has significantly improved the ability of coastal populations to prepare for and mitigate the impacts of Kallakkadal.
• By providing timely and accurate forecasts, this system helps coastal communities take proactive measures to protect lives and property from the sudden onset of swell surges.

How Kallakkadal different from Tsunami?
• Nature of Events:
o Kallakkadal manifests as a sudden flash flood event, occurring without any discernible alteration in local winds.
o Conversely, tsunamis are characterized by a series of massive waves generated by underwater disturbances, typically earthquakes.
• Cause:
o Kallakkadal is primarily triggered by strong winds, particularly in the southern Indian Ocean.
o Tsunamis, on the other hand, result from seismic activity such as earthquakes, underwater landslides, or volcanic eruptions.
• Wave Characteristics:
o Tsunamis exhibit relatively small wave heights offshore, often going unnoticed until they approach the coastline with tremendous force.
o In contrast, ocean waves, including Kallakkadal, have shorter wavelengths of only 30 to 40 meters, while tsunamis boast remarkably long wavelengths, spanning hundreds of kilometers.