Facing the real threat of vanishing beneath the sea by 2036, Kariyachalli Island home to one of India’s four major coral reefs is now the focus of an ambitious marine restoration project by the Tamil Nadu government.
Under the Tamil Nadu Sustainably Harnessing Ocean Resources (TNSHORE) initiative, the state will deploy 8,500 artificial reef modules, plant seagrass beds, and restore coral ecosystems around the shrinking island in the Gulf of Mannar, a region known for its rich marine biodiversity.
Island Shrinking Fast Over 70% Lost Since 1969
The uninhabited island has lost more than 70% of its landmass since 1969, shrinking from 20.85 hectares to just 3.14 hectares at high tide today. This rapid erosion is being driven by sea-level rise, reef degradation, and climate change-induced weather events. According to a 2025 report by IIT Madras, the island could disappear entirely by 2036 if urgent action is not taken.
“This is one of India’s most ecologically sensitive marine zones. We must act now,” said Supriya Sahu, Additional Chief Secretary of the Department of Environment, Climate Change and Forests.
How the Project Works
The artificial reefs designed in trapezoidal shapes made from ferrocement and steel will be placed underwater to reduce wave energy, trap sediment, and shield the island from erosion. Each module weighs up to 3 tonnes and stands 2–3 meters tall. Their perforated design will allow water and nutrients to circulate, fostering new marine life.
The modules were scientifically developed by IIT Madras in collaboration with the Suganthi Devadason Marine Research Institute (SDMRI) in Thoothukudi.
Alongside the reef structures, officials will plant native coral species and seagrass beds to enhance biodiversity and support marine species such as dugongs (sea cows), which feed on seagrass.
A Race Against Time and Climate
“The coral reefs act as the island’s first line of defense. As they disappear, the island becomes more vulnerable to cyclones, tsunamis, and further erosion,” said Sahu. Over one-third of Kariyachalli’s coral is already bleached, and while 2025 has so far seen limited bleaching, experts remain cautious.
To fund this critical intervention, the Tamil Nadu government has allocated ₹50 crore, targeting three acres of coral planting and four acres of seagrass restoration.
Timeline and Future Outlook
Deployment of the reef modules will begin in August 2025, with a 45-day installation schedule. The first signs of ecological recovery are expected within a year, depending on favorable environmental conditions.
This initiative is seen not just as a last-ditch effort to save one island, but also as a model for climate adaptation and coastal resilience across India’s vulnerable marine zones.
With time running out, Kariyachalli now stands at the center of India’s fight to preserve marine ecosystems, protect biodiversity, and build defenses against the rising tide of climate change.