Rising sea levels are slowly turning sinking islands into a reality, and to combat that, Tamil Nadu has come up with a novel idea to protect those islands sinking near the Gulf of Mannar – deploying artificial reefs.

Indiscriminate coral mining and destructive fishing practices over the past few decades have resulted in two of the islands getting fully submerged while Vaan – one of the 21 islands in the Gulf of Mannar, and a marine biodiversity park – was on the verge of submergence in 2015. Its area went down from 16 hectares in 1986 to two hectares in 2014.

Between December 2015 and August 2016, the area of Vaan went up by 2.24 hectares in low tide and 1.8 hectares during mean tide. The restoration of Vaan is funded by the National Adaptation Fund for Climate Change under the Ministry of Environment, Forests and Climate Change at a cost of Rs 25 crore.

A first in India to rescue and restore sinking islands, deployment of artificial reefs parallel to the sinking island in the seaward side lessens the effect of currents and waves, thereby increasing fish habitats and protecting their diversity. Natural corals attach themselves to artificial reefs over time and the process of regeneration takes over.

Owing to the success in Vaan, Tamil Nadu has approached the Green Climate Fund for additional funding of Rs 100 crore to undertake the restoration of two more islands.

Based on wave dynamic and bathymetry studies conducted by the Indian Institute of Technology Madras (IIT M), the design of artificial reefs and locations for deployment were finalised. The concrete reefs have been deployed 250 metres from the island in a semi-circular constellation. In the first two phases, 4,600 modules have been deployed in eight months. With additional funding, the plan is to take the total number of artificial reefs to 10,000 in two layers.