Kallakkadal
Also called: Swell surge · Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Beyond NCERT
Meaning
Kallakkadal means "sea thief" in Malayalam. It is sudden flooding of the Kerala coast by the sea, often on a calm day. It is caused by long swells, waves that have travelled very far from storms in the distant Southern Ocean. There is no strong local wind or storm to give a warning, so the sea seems to "steal" in without notice. It can flood homes, damage boats and wear away the coast.
Example
Kallakkadal floods have hit coastal villages in Kerala, along the Arabian Sea. To give early warning, INCOIS (Indian National Centre for Ocean Information Services) started its Swell Surge Forecast System in 2020.
Don't confuse with
- Tsunami: raised by an undersea earthquake or landslide, not by distant storm winds.
- Storm surge: caused by local strong winds and low air pressure, as in a cyclone. Kallakkadal comes with no local storm at all.
Related concepts
- Wave
- Orbital motion of water particles
- Fetch
- Wave height
- Wavelength
- Swell
- Breaking of waves
- Longshore drift