Context: Hyderabad-based INCOIS has issued an alert to coastal States on the possibility of swell surges and rough sea conditions.
About Swell Waves:
High-Energy Swell Waves
All swells are created by wind blowing over the surface of the ocean. When strong winds persist over vast distances (such as during storms), they generate waves. The strength, duration, and area of the ocean that the wind affects determine the size of the waves, how far they’ll travel, and the energy they carry when they reach the shore.
Working:
- Wind Energy: As winds blow across the ocean, they transfer energy to the water surface. This energy causes ripples to form, which eventually evolve into waves.
- Distance and Duration: The longer the wind blows and the greater the distance it covers, the more energy is transferred to the waves. Consequently, the waves become larger and cover more distance.
- Swells: Swells can be categorized based on their origin:
- Groundswell: These swells originate from winds far out at sea, covering longer distances. They have longer swell periods and more energy. Groundswells often result in cleaner, organized surf conditions.
- Windswell: Wind swell forms closer to the shore. The swell period is shorter, waves are less organized, and they arrive faster.
Issuing Authority: Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS).
Recipient States: Coastal States of Goa, Maharashtra, West Bengal, Odisha, Tamil Nadu, Kerala, Lakshadweep, and Andaman & Nicobar Islands.
Alert Content:
- INCOIS alerted coastal states about the possibility of high-energy swell waves over the weekend.
- Urged the total suspension of operational and recreational activities at beaches and nearshore regions on Saturday and Sunday.
- Advised fishermen and coastal populations to be cautious about potential surge waves, especially in low-lying areas.
Scientific Explanation:
- Senior scientist T. Balakrishnan Nair explained that high-period swells originating approximately 10,000 km away from the Indian coast in the southern Atlantic Ocean on April 26 were causing high-energy swell propagation towards Indian coastal regions.
- Expected impact: hitting the southern tip of India early Saturday, potentially causing coastal flooding in low-lying areas when combined with high tide conditions.
Safety Recommendations:
- Small vessels cautioned against plying nearshore.
- Recommended anchoring boats at a fair distance from each other to prevent damage.
Special Advisory for Kerala:
- Kerala coastal communities advised to remain vigilant.
- State put on red alert for high-energy swell waves, locally known as 'Kallakadal' (rogue sea), likely lasting until 11:30 p.m. on Sunday.
- Potential swell waves: ranging from 0.5 meters to 1.7 meters high in low-lying areas.
Actions by Kerala State Disaster Management Authority (KSDMA):
- Issued directions to suspend recreational activities along beaches.
- Advised coastal residents to temporarily evacuate if necessary.
- First instance of a red alert being issued for the State regarding the Kallakadal phenomenon, according to KSDMA member secretary Sekhar Kuriakose.