The Pallikaranai marshland, the only urban wetland of Chennai city, had miserably shrunk from its expanse of 5,500 hectares recorded in 1965 to just about 600 hectares in 2013 owing to large scale development of residential areas, Information Technology parks, institutions of higher education and related infrastructure, according to Senior Counsel P.S. Raman of Madras High Court.
In a report submitted before a Division Bench of Justices S. Manikumar and Subramonium Prasad on Monday in his capacity as an amicus curiae, he said, the marshland was situated about 30 km inland of the Bay of Bengal. Originally formed as a salt marsh created by the backwaters of Bay of Bengal, it now receives freshwater through rains and surplus water from 31 sub-urban water tanks.
It was surrounded by Velachery in the north, Medavakkam in the south, Kovilambakkam in the west and Okkiyam Thoraipakkam in the east. The northern and southern portion of the marshland drain towards Buckingham Canal through the Okkiyam Maduvu. The marshland provides crucial eco system services such as flood mitigation, groundwater recharge, fishing and recreation.
The amicus also said, one of the main reasons for the 2015 Chennai floods was the sand bar formation (accumulation of silt and waste) near the canal mouth of estuaries, creeks and unchecked urban development that prevented exit of natural water run-off. Further, due to destruction of natural recharge zones in the marsh, groundwater level in the localities nearby had gone down.
Mr. Raman suggested that two garbage dumping yards, one operated by Chennai Corporation on 70 hectares and another by Alandur Municipal Corporation on the marshland should be shut down and shifted elsewhere. Due to dumbing of garbage, the marsh, in its current ecological conditions, emits more carbon dioxide and methane than it absorbs, he pointed out.
The amicus also said the Perungudi sewage treatment plant occupying 250 acres of prime marshland was another great threat to fragile ecosystem. Insisting upon removing encroachments at the earliest, he said: “There are also Central government buildings such as Mass Rapid Transport System (MRTS) occupying approximately 100 acres.
“The National Institute of Ocean Technology (NIOT) with 20.25 hectares and the Central Wind Energy Technology along with IT parks and residential buildings within Pallikaranai marshland. These structures in close proximity to the marshland pose risk to birds through collision. There have been no systematic studies of risk of such collision.”
He pointed out that the marshland forms part of the Central Asian flyway or migration route of water birds that link their northern most breeding grounds in Russia to the southernmost non breeding or wintering grounds in West and South Asia, the Maldives and the Indian Ocean Territory. It was an important stopover for the migratory species for resting and refuelling.
It was further suggested that the Chennai Corporation should be directed to give away 100 hectares of the marshland in its occupation to the forest department since the proposal was pending for quite a few years. The amicus also filed a separate report with regard to the Kaluveli marshland near Tindivanam in Villupuram district.
He said, the floodplain of Kaluveli had been reduced from 600 square kilometres to 75 square kilometres. After taking the reports on file, the judges granted time till August 28 for Additional Government Pleader E. Manoharan to file a response on behalf of the State government.