South Atlantic Ocean Triggers 'Kallakkadal' In Kerala, Coastal Areas Flooded | Phenomenon Explained

High sea waves, also referred to as surge waves, have flooded hundreds of houses in several coastal areas of Kerala since Sunday. Due to the rough seas experienced in many coastal areas of Kerala, beach tourism activities have been halted in Thiruvananthapuram, Kollam, Alappuzha and Thrissur districts.

The waves, locally referred to as 'swell surge' or 'kallakkadal,' are expected to continue along the eastern coast of India, including Andhra Pradesh, Odisha, West Bengal, and the Andaman and Nicobar Islands.

What Is Kallakkadal?

Kallakkadal, a term used by local fishermen, combines the Malayalam words 'Kallan' (thief) and 'Kadal' (sea). It refers to coastal flooding during the pre-monsoon season in April and May caused by swell waves on the southwest coast of India.

These waves are formed by ocean swells generated by distant storms such as hurricanes or prolonged periods of strong gale winds. The energy transfer from the air to the water during such storms results in the formation of towering waves that can travel thousands of kilometres until they reach the shoreline.

Also Read | Sikkim Flash Floods Are A Reminder That Disasters Are Not So ‘Natural’

Typically, Kallakkadal occurs due to powerful winds in the southern Indian Ocean, leading to the formation of ocean swells that travel northward and reach the coast within a few days.

The recent occurrence happened following a low-pressure system's movement over the region around March 25 from the South Atlantic Ocean, approximately 10,000 kilometres away from the Indian coastline.

The Indian National Centre for Ocean Information Services (INCOIS), a central government agency that issues weather warnings for fishermen in the country, found that due to a low-pressure system entering the Indian Ocean, very high waves up to 11 metres in some areas were formed and reached the Kerala coast.

Tsunami vs Kallakkadal

Tsunami and Kallakkadal are two distinct phenomena often confused due to their powerful sea waves.

• Tsunamis result from underwater landslides or earthquakes, causing massive waves that travel across oceans and devastate coastal areas.

• Kallakkadal, on the other hand, is caused by meteorological conditions in the Southern Ocean around 30° South, leading to swell waves surging towards the coast and flooding land areas.