Pallikaranai Wetland

• Category: Inland Aquatic Biomes.
• Geographic Location: Asia.
• Summary: Government action is needed to stop the degradation of this wetland into a wasteland.

The Pallikaranai wetland is a freshwater swamp near the Bay of Bengal, about 12 miles (20 kilometers) south of Chennai, the capital city of the state of Tamil Nadu in southeastern India. It is the last remaining wetland ecosystem of the city of Chennai, and one of the few remaining in southern India. In the twenty-first century, the city is left with only around twenty-seven bodies of water. As one of the few remaining freshwater sources, the Pallikaranai wetland is crucial for supporting life and mitigating flooding in the connected water bodies in and around Chennai. The smaller wetlands that surround Pallikaranai serve as the only source of irrigation for the area. Together, these wetlands are an important resource for bird migration and nesting, but human activities, such as dumping of chemical and other toxic wastes, has severely impacted the area.

Wetland Essentials

Wetlands cover approximately 6 percent of Earth’s surface but serve as homes for around 40 percent of the world's plant and animal species. Wetlands are defined as lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface, or the land is covered by standing water that does not exceed 20 feet (6 meters). Human civilization originated in wetlands habitats such as the floodplains of the Indus, the Nile Delta, and the Fertile Crescent of the Tigris and Euphrates Rivers. This is in large part because wetlands are home to diverse plant and animal life. Biologically, the wetlands are among the most fertile ecosystems.

India has 27,403 documented wetlands, of which 23,444 are inland and 3,959 are coastal wetlands. The coastal type occupies 2,606 square miles (6,750 square kilometers). The share of wetlands in India overall amounts to 17 million acres (7 million hectares). One-third of these, however, have been wiped out, altered, or degraded.

Among ecological services, wetlands help check floods and mitigate the effects of natural disasters, including cyclones and tidal waves. Wetlands can store water for a longer period than other habitat types. They assist in erosion control, as they are located between water bodies and high ground; the roots of the vegetation in the wetlands protect soil from high-impact events such as wave action, wind, and heavy rainfall. Given that one-third of all wetlands in India are gone or heavily damaged, preserving areas such as the Pallikaranai becomes even more important than ever.

Pallikaranai Biota

The flora of the Pallikaranai wetlands consists primarily of aquatic plants, reeds, liana, and sedges. Acanthus, water lettuce, water hyacinth, joyweed, swamp morning glory, snowbush, and paspalum are featured across marsh areas, as well as transition areas. Among the sedges are umbrella papyrus, purple nutsedge, and slender cyperus. Large tracts of marsh grasses and pastures adjoin the wetlands areas.

The Pallikaranai wetland is home to several endangered species and acts as a breeding, feeding, and sheltering ground for many species of migratory birds. At least 125 avian species, both transient and permanent, have been recorded here. Among them are greater flamingo, glossy and white ibis, purple and Indian pond heron, little grebe, grey-headed lapwings, bushlark, various bitterns, ducks, pipers, pheasant-tailed jacana, yellow-wattled lapwing, and spot-billed pelican. The birds here are joined by twenty-one reptile species, ten mammalians, ten amphibian types, five crustaceans, nine mollusks, forty-six fish, and seven butterfly species.

The more frequently seen fish species include striped snakehead, long-fin eel, and stinging catfish; other common species here are mullet, glass fish, razor belly, peninsular olive barb, and long-whiskered catfish.

Threats

Water for irrigation in Tamil Nadu and drinking water availability in Chennai and its environs have been shrinking at an alarming rate. During the monsoon season, the connected water bodies bring along sewage, thereby making Pallikaranai a dump site. The topography of the swamp retains the excess water from the connected water bodies during their floods but also releases the accumulated toxins from it back into the ecosystem—sometimes in greater concentration—during heavy weather events. The deterioration of the wetland proper may also result in damage to neighboring water bodies. Outrage at the amount of garbage and chemicals dumped in and around the area has led to many calls for clean-up, regulation, and enforcement to preserve the wetlands.

The external manipulation of this wetland ecosystem began in 1806, with the construction of the 262-mile (422-kilometer) Buckingham Canal. The anthropogenic changes in and around this wetland cut much of the natural drainage channel network, thereby aggravating the frequency and intensity of floods. Flooding has also increased due to rapid urbanization; the growing number of inhabitants in the city of Chennai in the first decades of the twenty-first century largely outpaced the capacity of the 31-square-mile (80-square-kilometer) Pallikaranai wetland to process water and suspended and dissolved materials. Further, global warming is increasing the damage already sustained—and to come—from the threats of rising sea levels, saltwater intrusion, soil erosion, and invasive species penetration.

The government of Tamil Nadu, to protect the flora and fauna of the wetlands, at last in 2007 declared a major portion to be a reserve forest, thus setting its monitoring and preservation under the domain of the Forest Department. In 2018, the state government began restoring the wetlands, using money from the National Adaption Fund for Climate Change. In July 2022, the Pallikaranai wetlands received the Ramsar tag, an award that is part of UNESCO's Ramsar Convention, an intergovernmental treaty to preserve wetlands. This will ensure additional protection of the area.

In 2024, the National Green Tribunal (NGT) required the government to relocate their buildings, as well as apartments and IT parks, that were invading the space of the marshland. Additionally, plans to eliminate a portion of the road between Thoraipakkam and the Kamatchi Hospital Junction constructed in 2001, encroaching the wetland's borders, were announced. The 2.1 kilometer (1.3 mile) stretch was to be replaced by a high-level bridge.

Bibliography

Ali, Salim. The Book of Indian Birds. Bombay Natural History Society, 1996.

Jayaraman, Padmaja. "Ramsar Tag Secured, What Is the Way Ahead for the Pallikaranai Marshland?" Citizen Matters, 29 Aug. 2022, citizenmatters.in/pallikaranai-marshland-ramsar-status-conservation-ecosystem. Accessed 2 Nov. 2024.

Murali, Jayanthi. Wetlands: Environmental Degradation, Water Quality and Economic Valuation of Wetlands (A Case Study of Pallikaranai Marshland). Notion Press, 2021.

Oppili, P. “Pallikaranai Vulnerable to Devastating Floods: Study.” The Hindu, August 25, 2007.

"Pallikaranai Marsh Reserve Forest." Ramsar Sites Information Service, 2022, rsis.ramsar.org/ris/2481. Accessed 2 Nov. 2024.

Raj, P.P.N., et al. “Consolidated Checklist of Birds in the Pallikaranai Wetlands, Chennai, India.” Journal of Threatened Taxa, vol. 2, no. 8, 2010, pp. 1114–18, doi.org/10.11609/JoTT.o2220.1114-8. Accessed 2 Nov. 2024.

Ramesh, R., et al. Database on Coastal Information of Tamil Nadu. Institute for Ocean Management, Anna University, 2008.