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Current Affairs

Pallikaranai Marshland under threat

Date: 28 August 2019 Tags: Biodiversity

Issue

 

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.

 

Background

 

The marshland is situated about 30 km inland of the Bay of Bengal. It was originally formed as a salt marsh created by the backwaters of Bay of Bengal but now receives freshwater through rains and surplus water from 31 sub-urban water tanks.

 

Details

  • The marshland provides crucial eco system services such as flood mitigation, groundwater recharge, fishing and recreation.
  • It is also said that one of the main reasons for the 2015 Chennai floods was the sand bar formation 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 has gone down significantly.

Importance of Marshland

  • 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 is also an important stopover for the migratory species for resting and refuelling.

Threats faced by Marshland

  • IT parks and residential buildings have been constructed 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.
  • Central government buildings such as Mass Rapid Transport System (MRTS) and sewage treatment plants occupying certain area has posed another great threat to fragile ecosystem.
  • Due to dumbing of garbage, the marsh, in its current ecological conditions, emits more carbon dioxide and methane than it absorbs.