Chief minister J Jayalalithaa declared the Pallikaranai marsh a protected area in 2005, but now her party’s government has decided to dredge one of the last refuges of migratory birds in the city. The Greater Chennai Corporation believes the move will prevent flooding in the nearby residential areas, but naturalists and water experts are shocked and warn the ecosystem could be damaged.
A Chennai Corporation source said about Rs1,000 crore is the budget for this work, which is expected to be launched on Monday by chief minister Edappadi K Palaniswami with a visit to the marsh.
An expert on the Pallikaranai marsh, who spoke on condition of anonymity, said it is like a giant sponge. It will absorb, retain and slowly discharge the water. It acts as a natural drain that carries flood water to the Oggiyam Maduvu and to Buckingham Canal and on to the Bay of Bengal.
Former PWD assistant executive engineer S Thirunavukkarasu said the marsh is in the shape of a bowl. It absorbs flood waters from more than 55 lakes in and around South Chennai and its suburbs. Dredging this marshland eco-system will have a negative impact on its eco-system, he warned.
Conservationist T Murugavel asked whether the dredging proposal was based on any study. Now is the time migratory birds, waders and raptors visit the marsh. Dredging will destroy the nests of the migratory birds, he said.
In 2005, Jayalalithaa declared the marsh a protected area after an aerial survey of flood-hit Velacherry and its surroundings. The declaration was announced on November 12 to coincide with the birthday of the father of Indian ornithology Salim Ali.
Biodiversity researchers have recorded 155 species of birds, 100 species of fish and 141 plant species in the marsh. Originally pread over 7,000 hectares, the marsh has shrunk to 695.85 hectares as a result of encroachments over the years. Conservationists fear dredging could spell the beginning of the end for the marsh that remains.