page_title: Pallikaranai wetland
section_title: Location and ecology
hierarchical_section_title: Pallikaranai wetland / Location and ecology
caption_attribution_description: English: Hundreds of Spot-billed pelicans congregating during dawn on high tension cables in Pallikaranai Wetland, Chennai.
context_page_description: Pallikaranai wetland is a freshwater marsh in the city of Chennai, India. It is situated adjacent to the Bay of Bengal, about 20 kilometres south of the city centre, and has a geographical area of 80 square kilometres. Pallikaranai marshland is the only surviving wetland ecosystem of the city and is among the few and last remaining natural wetlands of South India. It is one of the 94 identified wetlands under National Wetland Conservation and Management Programme operationalised by the Government of India in 1985–86 and one of the three in the state of Tamil Nadu, the other two being Point Calimere and Kazhuveli. It is also one of the prioritised wetlands of Tamil Nadu. The topography of the swamp is such that it always retains some storage, thus forming an aquatic ecosystem. A project on 'Inland Wetlands of India' commissioned by the Ministry of Environment and Forests, Government of India had prioritised Pallikaranai marsh as one of the most significant wetlands of the country. The marsh contains several rare or endangered and threatened species and acts as a forage and breeding ground for thousands of migratory birds from various places within and outside the country.
context_section_description: The marshland is located along the Coromandel Coast south of the Adyar Estuary. It is surrounded by the expressway of Old Mahabalipuram Road and the residential areas of Perungudi, Siruseri, Pallikaranai, Madipakkam, Velachery and Taramani. An extensive low-lying area covered by a mosaic of aquatic grass species, scrub, marsh, and water-logged depressions, it is connected to 31 different water bodies, all of which release surplus water into the marsh during the monsoons. It has a catchment of 235 square kilometres (91 sq mi) that includes the urban sprawls of Velachery, Pallikaranai and Navalur. The terrain of the area is generally plain with an average altitude of about 5 metres (16 ft) above mean sea level. It receives an annual rainfall of 1,300 millimetres (51 in), mostly during the northeast monsoon (September–November), but also during the southwest monsoon (June–August). Temperature ranges from 35 to 42 °C (95 to 108 °F) during the summer, and from 25 to 34 °C (77 to 93 °F) in the winter. A large part of the southern region of Chennai was historically a flood plain as evidenced by the soil type of the region, which is described as recent alluvium and granite gneiss. The entire landscape comprises a coastal plain with intermittent and overlapping habitat types of cultivated land, wetlands and scrub forests. The wetlands comprises a large marsh (the Pallikaranai marsh), smaller satellite wetlands, large tracts of pastureland and patches of dry forests. The marsh has been cut into two for a road with no free flow underneath. Spread over 50 square kilometres (19 sq mi) at the time of Independence in the 1940s, about 90% of the wetland was lost as the city expanded and it continued shrinking at an alarming rate. The marshland has shrunk over the last four decades following the creation of residential areas around it, including Perungudi, Siruseri, Pallikaranai, Madipakkam, Taramani and Velachery. Nearly a decade ago, about 120 species of birds were sighted at the marsh. However, their population has sharply decreased now due to various ecological disturbances in the region. The original expanse of the marsh in 1965 was about 5,500 hectares (14,000 acres). The expanse estimated on the basis of the Survey of India toposheet of 1972 and aerial photographs (Corona) of 1965 was about 900 hectares (2,200 acres), which has shrunk to about 600 hectares (1,500 acres). Today, the marsh extends up to Sholinganallur Road.
  Excess rainwater is drained into the sea through a channel called the Oggiyam Madavu, a contiguous portion of the marsh at Oggiyam Thorapakkam draining into the Buckingham Canal, which in turn discharges into the Kovalam estuary. Locally known as Kazhiveli (a generic Tamil name for marshes and swamps), the marsh drained about 250 square kilometres (97 sq mi), through two outlets, namely, the Okkiyam Madavu and the Kovalam creek. Remnant forests can be observed within the Theosophical Society campus, Guindy National Park–IIT complex and the Nanmangalam Reserve Forest.
  The heterogeneous ecosystem of the marshland supports about 337 species of floras and faunas. Of the faunal groups, birds, fishes and reptiles are the most prominent. Pallikaranai marsh is home to 115 species of birds, 10 species of mammals, 21 species of reptiles, 10 species of amphibians, 46 species of fishes, 9 species of molluscans, 5 species of crustaceans, and 7 species of butterflies. About 114 species of plants are found in the wetland including 29 species of grass. These plant species include some exotic floating vegetation such as water hyacinth and water lettuce, which are less extensive now and highly localised. The region has a bird bio-diversity about 4 times that of Vedanthangal. It is also home to some of the most endangered reptiles such as the Russell's viper and birds such as the glossy ibis, grey-headed lapwings and pheasant-tailed jacana. Cormorants, darters, herons, egrets, open-billed storks, spoonbills, white ibis, little grebe, Indian moorhen, black-winged stilts, purple moorhens, warblers, coots and dabchicks have been spott
caption: Hundreds of Spot-billed pelicans congregating during dawn on high tension cables in Pallikaranai Wetland, Chennai.
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