El Niño and rough sea changes bring frequent swell surge alerts to Kerala coast

Unusual sea conditions linked to El Niño have triggered frequent swell surge alerts along India's western coast during the southwest monsoon, marking a major shift from past years when such warnings only came during the pre-monsoon period. The Indian National Centre for Ocean Information Services issued a red alert for swell surge lasting two days along the entire Kerala coast and southern Tamil Nadu. The State Disaster Management Authority extended this alert, warning residents to stay vigilant against strong waves, coastal flooding, and sea erosion. Meanwhile, INCOIS issued an orange alert for coastal Karnataka. Swell surges, locally known as kallakadal, happen when distant storms or fierce gale winds transfer huge energy into water, creating massive waves that travel thousands of kilometres. This year, the Kerala coast has faced 14 swell surge alerts, including two red alerts. Alappuzha district felt the impact when heavy waves flooded coastal roads and disrupted traffic. These surges occur even as mainland Kerala reports a 28 percent deficit in southwest monsoon rainfall.

Expert View and Causes

INCOIS director Dr T M Balakrishnan Nair explained that El Niño has altered sea conditions by keeping the sea relatively calm while missing normal monsoon winds. This calm surface encourages more fishing activity, raising risks when powerful swell waves arrive from 1,000 to 2,000 kilometres away. In past years, regular monsoon waves mixed with swell waves to create constantly rough seas, hiding individual swell surges and removing the need for separate warnings. Because the deep southern sea lets swell waves keep their energy, they hit southern Kerala and Tamil Nadu's Kanyakumari region with full force.

Context

Swell surges are a natural oceanographic phenomenon where distant weather events create powerful waves that travel across vast expanses of water to strike distant coastlines. State disaster management bodies routinely issue coastal alerts to protect fishermen and beachgoers when these unexpected wave events threaten populated shores.