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Dredging Chennai’s Pallikaranai Marsh Is an Ecologically Bad Idea – Here Is Why

Dredging Chennai’s Pallikaranai Marsh Is an Ecologically Bad Idea – Here Is Why

Birds in Chennai’s Pallikaranai marsh. Photo: Ramesh SA/Flickr, CC BY-ND 2.0.

On November 30, after visiting the Pallikaranai area in Chennai’s south, Tamil Nadu chief minister Edappadi K. Palaniswami told journalists that the state was planning to dredge the marshland.

The decision, apparently taken after much deliberation, is aimed at mitigating the flooding around the area. Sources in Chennai Corporation say the project would cost about Rs 1,000 crore.

The decision of the government to dredge the marshlands betrays not just its short-sightedness but is likely to expose Chennai to more dangers in future.

Pallikaranai is a naturally formed marshland, and was declared as a protected area by the AIADMK government, headed by J. Jayalalithaa, in 2005. That the present government, which claims to follow in the footsteps of Jayalalithaa, would go against her own decision is a sad twist of irony.

Pallikaranai is the only urban wetland in Chennai, and has faced many ecological disasters. In fact, studies have suggested that the marshland has significantly shrunk in size since 1965. According to reports, the size of the marshland was about 5,500 ha in 1965 but only 600 ha in 2013.

While the large-scale development of Pallikaranai as a residential area is the chief reason for its sad state, the reduction of its size has also led to groundwater depletion in the neighbourhood.

Apart from this, Pallikaranai continues to be a dumping yard for Chennai’s waste. On a daily basis, Chennai generates about 5,000 metric tonnes of solid waste, a part of which is emptied into two dump yards – one of which overlaps with the Pallikaranai marsh (the other yard is in Kodungaiyur). As we continue to discuss the importance of the marshland, a part of it is covered now with sand to facilitate the extension of roads in Perumbakkam, which is part of the marshland.

On the one hand, we have mushrooming residential projects, and on the other, the accumulation of waste, pollution and water from sewers. Amid these many challenges, Pallikaranai continues to preserve its importance.

Despite its shrinking space and the ecological damage, Pallikaranai is home to 65 species of migratory birds, 105 of native birds, 50 of fish, 15 of snakes, 10 of lizards, 11 of amphibians, 10 of mammals, 34 of butterflies, 20 of dragonflies, eight of cockroaches, 78 of plankton and 167 of plans. (All these numbers are according to a Tamil Nadu forest department field guide published in August 2020.) They have been able to survive because Pallikaranai continues to be a fertile swamp.

And by dredging this swamp, its biodiversity will be completely destroyed. The native painted stork and the migratory flamingo will almost certainly stop inhabiting Pallikaranai if the government presses ahead, bringing on a cascade of ecological collapse.

Also Read: The Ecological History of Chennai Might Surprise You

Pallikaranai is also a major stormwater drain and groundwater recharge system for Chennai. In fact, to understand Pallikaranai is to understand its hydrology. Pallikaranai soaks up water during heavy rainfalls like a sponge and releases them during dry spells. Dredging it will leave Chennai more vulnerable than it already is to flooding, and could also allow seawater to intrude.

In this regard, the government’s decision to dredge the marshland, and build a channel through it, is an extension of the Anthropocene mentality that views everything from the human point of view. But Pallikaranai is not a Chennai Corporation-owned water tank, and the corporation must preserve it as a marshland, as inconvenient as that is for the city, if Chennai is to survive as an inhabitable human settlement.

Most of India's solid waste ends up in landfills. Credit: designforhealth/Flickr, CC BY 2.0
Solid waste at the Pallikaranai landfill in Chennai. Photo: designforhealth/Flickr, CC BY 2.0

Declare Pallikaranai a protected zone

Indeed, Pallikaranai should be declared as a protected zone under the 2017 marshlands protection rules of the Environment Protection Act, 1986. The government should also declare Pallikaranai as a Ramsar site under the Ramsar convention for wetland protection. Tamil Nadu has over a hundred wetlands but except for Kodiyakarai, none of them are protected under the Ramsar convention.

Second, closer to the ground, the government should take steps to prevent sewage water from being let out into Pallikaranai. Currently, sewerage from neighbouring Velachery is directly let into Pallikaranai marsh. Third, the Chennai Corporation should stop dumping solid waste in Pallikaranai and adopt ecologically safe solid-waste management practices.

Fourth, the government should remove encroachments on the Pallikaranai marshland and prevent all future encroachments as well. And to better enforce these four conditions, the state should consider increasing the deployment of forest guards, who can also deter hunting. (There is also a street-dog menace: the dogs hunt in packs and kill birds and snakes.)

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Finally, it’s important that the government appoint a committee consisting of experts who have good knowledge of Pallikaranai’s biodiversity, and act on their suggestions.

The recent ‘Save Pallikaranai’ campaign achieved some measure of success within the city, but ultimately both the people and the government should realise that saving the marshland is also in their own best interests.

Chennai already bears the brunt of widespread ecological distress, and this will only get worse in the era of climate change. If the government also dredges the Pallikaranai marshland in this time, Chennai will only present a more vulnerable target.

G. Sundarrajan is a volunteer with Poovulagin Nanbargal, an environmental awareness and activism organisation.

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