Sri Lanka, India’s southern neighbour, plays a vital but often unseen role in coastal protection. It acts as a natural wall, shielding the southeast coast of India from powerful ocean swells that originate thousands of kilometres away in the Southern Ocean.
Swells are long, powerful waves generated far out at sea, particularly in the Southern Ocean around Antarctica. These waves can travel across oceans with minimal energy loss and often cause coastal flooding and erosion when they reach shorelines. Indian states such as Kerala frequently experience their impact on the west coast.
Despite travelling across the Indian Ocean and entering the Bay of Bengal, these swells rarely affect Tamil Nadu and Andhra Pradesh. The reason lies in Sri Lanka’s geographic position: the island sits directly in the path of these waves and blocks them from reaching India’s southeast coast.
This protective effect is similar to a man-made breakwater used in harbours to reduce wave energy. In this case, Sri Lanka functions as nature’s own breakwater.
Scientists from the Indian National Centre for Ocean Information Services (INCOIS) conducted the study using:
Their findings revealed that over 96% of long-period swells detected at Kollam never reached Pondicherry. When the Sri Lankan landmass was removed in computer simulations, the waves travelled freely to Tamil Nadu and Andhra Pradesh, confirming Sri Lanka’s role as a natural shield.
With climate change and rising sea levels altering coastlines, even minor geographic changes could redirect wave paths, exposing currently protected regions to marine hazards. Scientists stress the importance of including natural features such as islands and landmasses in coastal hazard assessments and early warning systems.
The research involved experts from:
The study was published in the Journal of Earth System Science.
Sri Lanka’s landmass acts as a natural shield, blocking powerful Southern Ocean swells from reaching India’s southeast coast. Using buoy data and advanced wave modelling, scientists confirmed that without Sri Lanka, these waves could strike Tamil Nadu and Andhra Pradesh. The study highlights the critical role of natural geographic barriers in reducing coastal risks, particularly in an era of rising sea levels and changing ocean patterns.
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