State adopts 'Tetrapod technology' to curb erosion near Kapil Muni Ashram

Kolkata: The state Irrigation department is adopting a nature-based solution known as 'Tetrapod' for curbing the erosion adjacent to Kapil Muni Ashram in Sagar Islands where lakhs of devotees from different parts of the country assemble every year during Makar Sankranti – when Ganga Sagar Mela is held.

"We will soon start a pilot project through which Tetrapod will be built along the coast covering an area of 850 metre. The basic plan is to utilise the silt carried by the sea waves to ultimately enforce coastal structures such as seawalls and breakwaters to prevent erosion," a senior official of state Irrigation department said.

Tetrapods are made of concrete, and use a tetrahedral shape to dissipate the force of incoming waves by allowing water to flow around rather than against them, and to reduce displacement by interlocking.

When sea waves will lash through the tetrapods, the water will get trapped inside the latter. The silt carried by the waves will settle down and siltation will start within the area. This will lead to the formation of coastal structures such as seawalls and breakwaters or sand dunes which will prevent erosion.

The state government has been trying for long to come out with a concrete solution to this problem and have consulted many experts including IIT Madras. Some technology was tried earlier but there has not been any fruitful outcome, as yet.

Tender for Tetrapod is in the matured stage and the total cost for the project will be to the tune of Rs 7-8 crore.

The sea is advancing at the rate of 15 metres a year. Experts fear that if the trend continues, there will be a need to relocate the Kapil Muni temple.

It is believed that the existing temple is the seventh at the site, after six structures built earlier were devoured by the sea.

Tetrapods have become popular across the world, particularly in Japan; it is estimated that nearly 50 per cent of Japan's 35,000 kilometers coastline has been covered or somehow altered by tetrapods and other forms of concrete.