Vaan Island Restoration Yields ₹61.67 Crore Benefits

A decade-long artificial reef restoration of Vaan Island in the Gulf of Mannar has delivered socio-ecological benefits valued at ₹61.67 crore, more than double its inflation-adjusted project cost. A technical assessment by the Tamil Nadu Coastal Restoration Mission, Suganthi Devadason Marine Research Foundation and IIT Madras reported a benefit-cost ratio (BCR) of 2.34, underscoring the economic viability of nature-based coastal restoration.

Vaan Island, one of 21 uninhabited coral islands in the Gulf of Mannar, had shrunk by 92% between 1969 and 2015 due to coral mining, reef degradation and sea-level rise.

Reversing Severe Coastal Erosion

To arrest rapid erosion, scientists deployed 10,600 specially designed artificial reef modules around the island from 2015 onwards. The intervention has been described as conclusive proof that severe coastal loss is reversible.

Geomorphic monitoring shows that the island’s area has expanded from 1.53 hectares in 2015 to over 2.3 hectares. The reef structures have stabilised sediment and reduced wave energy, enabling natural accretion processes to resume.

Ecological Recovery and Biodiversity Gains

The artificial reefs facilitated rapid biological colonisation. Researchers recorded an average of 81 coral colonies per module. Reef-associated fish density increased eight-fold, rising from 106 to 875 individuals per hectare.

The project also preserved 26 native plant species and improved overall marine habitat quality. Enhanced coral cover and fish biomass indicate strong ecosystem recovery in a previously degraded reef system.

Economic Valuation and Coastal Protection

Economic analysis found mainland coastal protection to be the largest benefit, valued at ₹28.57 crore, accounting for 46% of total gains. Regulating and supporting ecosystem services such as sediment trapping and nutrient cycling contributed ₹13 crore.

Direct fisheries and epibenthic gains added approximately ₹13.43 crore. Against an inflation-adjusted project cost of ₹26.37 crore, the initiative generated a net present value of ₹35.3 crore.

Important Facts for Exams

• The Gulf of Mannar hosts 21 coral islands along the Tamil Nadu coast.
• Artificial reefs are man-made structures designed to mimic natural reef functions.
• Benefit-Cost Ratio (BCR) above 1 indicates economic viability of a project.
• Coral reefs act as natural barriers against coastal erosion and storm surges.

Blueprint for Future Restoration

Officials said the Vaan model offers a replicable framework for protecting 20 eroding islands in the Gulf of Mannar, two of which have already submerged. The State has initiated a ₹50 crore restoration of Kariyachalli Island, with artificial reef deployment nearing completion, signalling a broader commitment to climate-resilient coastal management.