Pallikaranai Marshland
Why in News?
The Pallikaranai Marshland is in the news due to an intense legal and environmental battle over a strict National Green Tribunal (NGT) development freeze on real estate projects within a 1-kilometre radius of its boundaries.
Geographical Profile & Core Details
- Location: It is a unique freshwater and partly brackish water urban wetland situated about 20 kilometres south of Chennai, Tamil Nadu.
- Ramsar Site Designation: It was designated as a Ramsar Site of International Importance on April 8, 2022, legally protecting its critical status under international environmental treaties.
- Local Terminology: It is locally known by the generic Tamil name Kazhuveli, which translates directly to a floodplain or waterlogged area.
- Natural Urban Sponge: It drains a massive 250 sq. km catchment area across South Chennai, acting as the city's vital flood buffer by absorbing excess monsoon stormwater.
- Outlets: The marshland encompasses over 65 smaller interconnected satellite wetlands, discharging water into the Bay of Bengal through the Okkiyam Madavu channel and Kovalam Creek.
Rich Biodiversity & Fauna
- Avian Haven: Historically renowned as a major migratory bird hub, supporting over 115 distinct bird species, including Glossy Ibis, Grey-headed Lapwings, and Pheasant-tailed Jacana.
- Flamingo Habitat: It is one of the rare urban coastal aquatic habitats in India capable of hosting both Greater and Lesser Flamingos simultaneously.
- Diverse Ecosystem: Beyond birds, the marsh supports 10 mammal species, 21 reptile species (such as Russell’s viper), 10 amphibians, 46 fish varieties, and various crustaceans.
Critical Threats & Anthropogenic Pressures
- Massive Shrinkage: Spanning nearly 50 square kilometres in the 1940s, rapid urban expansion has shrunk the marshland by an alarming 90%, leaving behind a core protected forest of only about 698 hectares.
- Encroachment Proximity: The marsh is trapped amidst dense IT Corridors (Old Mahabalipuram Road), residential high-rises (Velachery, Perungudi), and Mass Rapid Transit tracks.
- Pollution and Leachate: Stagnant, untreated municipal sewage and toxic chemical leachate routinely seep into the wetland from the adjacent, unlined Perungudi dumpyard.
- Invasive Species Takeover: Nutrient-heavy water pollution has triggered severe outbreaks of invasive water hyacinths, turning parts of the marsh into hypoxic "dead zones" dominated by predatory African catfish.
