In the past two decades, Tamil Nadu has reportedly lost 41% of its shoreline to erosion. As an effort to protect the coastline, National Centre for Coastal Research is preparing a report to identify vulnerable areas and propose solutions to suit site conditions.
Mamallapuram, near the city, and Bommayarpalayam, near Puducherry, are some of the sites chosen to erect structures to prevent further erosion.
Based on a national assessment of shoreline changes and a status report for 1990-2016 prepared by the NCCR, the Centre and the National Institute of Ocean Technology are in the process of identifying erosion hotspots and executing short-term strategies for immediate protection.
At present, sea walls and groynes, a collection of boulders laid perpendicular to the coastline, are the major artificial structures put in place for protecting the shoreline.
Man-made problems
According to the report released recently, ports development, construction of dams in the rivers that block supply of sediments to coastline are some of the reasons for erosion apart from the natural causes such as sea-level rise and storms.
Citing the status report, M.V.Ramanamurthy, Director, NCCR, said of the Tamil Nadu coastline running to a distance of 991.47 km studied, along nearly 407.05 km, erosion has emerged as an issue. Only 23% of the coastline is having sand accretion.
“We are in the process of developing a combination of hybrid solutions to aid sand accretion according to the site conditions,” he said.
The Centre has completed projects in Puducherry and Kadalur Periyakuppam near Puducherry wherein beach nourishment by adding sediments and submerged reefs were implemented to reclaim the shoreline.
Submerged dykes using geosynthetic tubes to a height of 2.5 metres was another solution to arrest sea erosion. These would be laid nearly 150 metres into the sea.
The intensity of the waves is expected to be reduced with this technology.
40-km stretch under study
The entire coastline along the East Coast Road running to a distance of 40 km between Puducherry and Chennai would be studied for coastal erosion, he said.
“Nearly 20-metre width of the beach has been restored in Puducherry over the past one year. We will also jointly work with IIT-Madras that has initiated study on specific requirements for sand accretion in coastal areas,” Mr. Ramanamurthy added.
The project report, which is funded by Ministry of Earth Sciences, is expected to be submitted in about six months and the NCCR would work with Water Resources Department to implement the projects for coastal protection.
