CHENNAI: The innovative solutions offered by National Institute of Ocean Technology (NIOT) in Kadalur fishing village near Kalpakkam and Pondicherry to beat sea erosion are showing positive results. These were technology demonstrators that were unconventional and site-specific.
A round table discussion on ‘Shore Protection and Remediation using Eco-friendly Alternative Designs’ was organised at NIOT-Chennai to disseminate the experience and knowledge gained through the design, implementation and performance monitoring of the shore protection measures at two sites impacted by natural and man-made causes.
Giving a detailed presentation, National Centre for Coastal Research (NCCR) director M V Ramanamurthy said when the problem of sea erosion was noticed in Kadalur, which is south of Chennai and Pondicherry, demonstration studies along two shorelines was conducted and it was decided to design and implement appropriate sustainable environmental-friendly shore protection measures suitable to each of these two locations.
The results are for everybody to see. A new beach has formed along the shorelines and the economy there is thriving. At the Kadalur villages undergoing erosion with heavy loss of beach due to severe effects of storms Nilam and Thane, a submerged dyke was adopted because of its capability to dissipate energy of larger waves and in waters near the shore rather than completely blocking the waves thus augmenting the natural coastal resilience instead of interfering with it.
Officials said the dyke is made up of geosynthetic tubes filled with sand and stacked on the seabed with two tubes on the bottom and one on the top totalling height of 3.5m in 4m of water, with half a metre free board during low tide. There are gaps in between the dyke segments enabling local fishing boats to pass through. Dyke laying poses a challenge, as the entire operations are carried out in nearshore areas and a wave breaking zone, with shallow depths where big boats cannot operate.
“On completion of construction of dyke segments, the beach area started growing gradually. The beach slope has become gentle with accumulation of sand behind the dyke area. This dyke segment has effectively withstood effects of cyclones Vardah and Gaja and protected the coastline. Now, fishermen are able to beach-land their small boats and carry out activities like net mending, fish drying, repairs. Underwater videos indicate significant growth of mollusks providing substrate for fishery development, attracting variety of fish, lobsters and crabs,” NIOT officials said.
Similarly, the coastline of Pondicherry was rebooted with a wedge-shaped steel reef at the north, an offshore reef at the south along with beach nourishment. Today, the beach has already formed to the south of the reef to a significant extent and is still giving expectations that the city’s coastline can soon travel back in time to its sandy past.
The discussion was attended by Kerala Fisheries Department, national fisherfolk forum, Pondicherry, IIT-Madras, experts in the field of coastal engineering, Tamil Nadu Public Works Department, Central Water Commission, Andaman Lakshadweep Harbour Works and other government agencies.