The criticality of protecting and conserving the Pallikaranai Marsh, which is located in south Chennai needs no elaboration or further reiteration, especially in view of the sustained interest it has evoked across the country, and globally over the last decade. The following document therefore focuses on the strategy, processes and tools essentially for enabling the conservation of this Marsh.
Wetlands are the most important of life-supporting ecosystems that have sustained human lives and communities over the millennia. They 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 6 meters’. Evidently, this seemingly generic definition facilitates the inclusion of a large gamut of habitats ranging from mangroves to peats and bogs. This diversity while contributing to the enormous diversity of wetland organisms is also a significant impediment in evolving overall management strategies and plans. Further, wetlands in view of their transitional nature need to be managed with caution since the probability of losing their ecological structure and integrity through a process called ecological flip is rather high. Wetlands are therefore ideally managed using a decentralized framework of management; with locale specific management processes and tools.
A large part of south Chennai was historically a flood plain as evidenced by the soil type of the region, which is described as recent alluvium and granite gneiss. Spread over 50 sq. km, it comprised of a large Marsh (Pallikaranai Marsh), smaller satellite wetlands, large tracts of pasture land and patches of dry forests. The composite nature of the landscape wherein the entire landscape is defined as a coastal plain with intermittent and overlapping habitat types of cultivation, wetlands and scrub forests.
Locally known as Kazhiveli (a generic Tamil name for Marshes and swamps), the Pallikaranai Marsh drained about 250 sq. km, through two outlets viz. the Okkiyam Madavu (channel) in Okkiyam thuraipakkam and the Kovalam Creek. It is imperative that the phrase ‘draining’ is to be understood in the context of flood mitigation, ground water recharge and irrigation. It is not to be deciphered as a one shot flushing of water. Remnant forests can be observed within the Theosophical Society campus, Guindy National Park-IIT complex and the Nandamangalam Reserve Forest.
It is also of significance that the smaller wetlands that surrounded the Marsh served as the only source of irrigation for the area, which thrived on paddy and green leafy vegetable cultivation. This gave the Marsh a legendary status since the villages did not have wells or dug-out ponds, which are the norm in the northern districts of Tamil Nadu (TN).
The first known external manipulation of this system, which is part of the Coromandel Coast, was the laying of the Buckingham Canal. Devised as a navigation canal in 1806, of 421.55 km length, that connected Pedda Ganjam in Andhra Pradesh (AP) and Marakanam in TN, the canal served the primary purpose of ferrying salt. It is not well known that the canal was under private ownership and was then called the Cochrane Canal. In 1837, the Canal was taken over by the East India Company and renamed as the Government East Coast Canal. In 1876, it was rechristened the Buckingham Canal. The Buckingham Canal was devised as a salt water canal, tidal to a great extent in those parts where the river bars are open and utilized the numerous estuaries and backwaters along the East Coast.
The city of Chennai due to its immediate proximity to the neighbouring state of AP and the presence of the extensive Pulicat Estuarine Complex to the north, and the Bay of Bengal to the East, can expand only towards the west and south. The presence of the freshwater aquifer running parallel to the coast has contributed rather significantly to the expansion of the city’s boundaries in the south – which is one of the many pointers to the presence and importance of the South Chennai Floodplain.
While unplanned and ad-hoc human interventions have contributed to the large scale decimation of the landscape, the fundamental factor facilitating the degradation has been the continuation of the rather archaic system of land classification in the state by which the Pallikaranai Marsh was categorized as a wasteland.