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Ecological Heritage Sites of Chennai

Ecological Heritage Sites (EHS) are areas of remnant indigenous vegetation representing different range of landform, soil, plant associations, habitat or ecosystem that occur in a particular region. They are the remnants of unique vegetation types that exist in such regions and have high ecological value (Sanjeeva Raj, 2002). There are hundreds of EHS in India: Sundarbans, Chilka Lake and Pulicat Lake are but a few worth mention. In Chennai alone over 20 sites are identified as EHS and have been assessed and evaluated on various criteria such as the number of native species, degree of disturbance and the area covered by the site.

Classification of EHS in Chennai

According to their vegetation and natural resources, the EHS in Chennai are classified into five broad categories. They are:

 Estuaries  Adyar, Cooum
 Scrub-jungle  IIT campus, MCC campus, Guindy Park, Theosophical Society campus and Kattupalli Island
Water bodies  Temple tanks, Adambakkam Lake, Mogappair Lake, Red hills, Madhavaram Lake, Korattur Lake, Ambattur Lake and Pulicat Lake
 Wetlands  Pallikaranai, Velachery and Chembarambakkam
 Parks  Natesan Park, Nageshvara Rao Park, Panagal Park, etc.,

The EHS are noted for their richness of biological diversity but sadly a number of threats are associated with them.

Adyar Estuary

Chennai is one of the few cities having an estuarine ecosystem. The Adyar creek is of a tidal type and a part of the natural estuarine ecosystem located right in the heart of the city. The original creek area is about 100 acres. Of this, roughly about half the extent remains as a creek, where tidal effect is felt twice a day.

Adyar Estuary
Source: The Hindu, January 12, 2003

There are hundreds of EHS in India: Sundarbans, Chilka Lake and Pulicat Lake are but a few worth mention. In Chennai alone over 20 sites are identified as EHS and have been assessed and evaluated on various criteria such as the number of native species, degree of disturbance and the area covered by the site.

The Adyar River originates at Chembarambakkam tank in Tiruvallur district. It flows a distance of about 40 kms. to join the Bay of Bengal in the southern part of Chennai. At its mouth (the estuary), it takes a bend forming the creek. The estuary extends from the sandbar at the edge of the sea to the Adyar Bridge, with small islands inbetween. The creek begins near the Chettinad Palace.

Adyar Estuary

Source: The Hindu, January 12, 2003

The picture of an ecosystem would be incomplete without a description of its flora and fauna. The Adyar creek, inspite of the absence of mangroves, which is an essential part of an estuarine ecosystem, still exhibits a wide range of biodiversity. The flora found in the Adyar creek are Prosopis juliflora (Velikathan) along with Crotons sparciflorous and Ipomea biloba, Thespesia populnea, Cassia occidentalis, Cephalandra coccinia and Pongamia glabra, Abrus precatorius, Lantana camera, Zizyphus jujuba, Azadirachta indica, Morinda species, Antigonon species, Hyptis species and Acacia species. The fauna found here are gastropods and springtails, polychaetes, crabs, hermit crabs and oligochaetes. Many species of fish earlier found in abundance are no longer seen. Originally there were about 170 species of birds at the estuary now dominated by the omnipresent crows (Exnora Naturalists’ Club, 1997). The Adyar estuary is a textbook case of a fragile natural heritage losing out to frantic urbanization (Theodore Baskaran, 2003).

Threats

The Adyar Creek has several threats such as heavy accumulation of silt over a period of time. Slums have encroached upon more than half the footbridge. The remaining portion and its debris impede the flow of water. It is used as a garbage dump now. A number of cattle sheds, which are set up along the creek, not only reduce the width of the creek but also pollute it. The other sources of pollution are the raw sewage let in at various points from the encroachments, storm water drains and other upstream sources such as industries, hospitals and sewage pumping stations. Heavy encroachment along the creek has also resulted in gross pollution of the wetland, turning it into a health hazard (Exnora Naturalists’ Club, 1997).

The creek bed is heavily silted and the water is forced to take a meandering course. Both the banks of the creek are devoid of any native vegetation. The creek, once a paradise, has now been practically ruined.

Cooum Estuary

The name of Cooum appears to be derived from Tamil Literature. The word “coovalan” denotes a person who is well versed in the science of hydrology. It is likely, that the River Cooum might have derived its name from such a usage (Rajamanickam, 1970; Mudaliar, 1981). The River Cooum, once a fresh water source is today a drainage course collecting surpluses of 75 small tanks of a minor basin. The length of the river is about 65 km, of which 18 km, fall within the Chennai city limits (Sundaresan, 1986).

The Cooum then ....
Cooum Estuary

Source: The Hindu, Septembet 19, 2002

The River Cooum is a typical example for biodegradation of a natural watercourse. It enters Madras city limits near Arumbakkam and winds its way through the city for about 18 km flowing through Choolaimedu, Chetpet, Egmore and Chindadripet. Because of its twisting course through the heart of the city, the river carries the major portion of the storm water drainage from Madras city during the rainy season.

.... and now

Cooum Estuary

Source: The Hindu, June 4, 2002

The Kesavaram dam diverts the river into the Chembarambakkam Lake from which water is utilized for the supply of drinking water to the city of Madras. Thereafter, the flow of water in the river is totally reduced (Kothandaraman, et.al., 1986).

Threats

The River Cooum carries large quantities of sullage, sewage and cattle wash. The river is stagnant and contains a lot of silt. The silt is supposed to be two to three feet deep at certain places. It is reported that the net amount of silt deposited in the river is 3200 tonnes/year. As a result, the oxygen content is reduced to a level below which fish cannot live (Azariah, J. and Azariah, H. 1987a).

Sand mining, increasing hutments, dumping of wastes and encroachments. They cause significant damage to plants, animals and birds. Developmental activities also cause irreversible changes because they badly displace the native vegetation.

Reduction of fish species
Year No. of fish species
1949 49
1957 - 1959 30
1975 - 1979 21
2000 No fish

The water body has been subjected to heavy stress due to organic pollution, thus preventing it from regenerating itself. Several places along the banks are used to rear and perpetuate buffaloes. There are unauthorised hutments situated on the banks and these directly dump garbage, excreta and sullage into the Cooum. Several hotels in the city are discharging sewage into the river at various points. Effluents from a variety of industries heavily pollute it (Rao, 1987). Therefore, far from being an asset to the city, the river has turned into a black spot mainly due to the human activities. The river is an “eye sore” to permanent residents and visitors alike and is not fit for any use.

Conclusion

The river mouths or estuaries have also been identified as EHS, which includes Adyar and Cooum. The major threats to these EHS are the increasing pressure of human activities such as sand mining, increasing hutments, dumping of wastes and encroachments. They cause significant damage to plants, animals and birds. Developmental activities also cause irreversible changes because they badly displace the native vegetation.

The people and the Government should take necessary action to stop sand mining activity and vehicular traffic must be banned in order to preserve the unique ecosystems.

References

  1. Azariah, J. and Azariah,H., “Let the fishes live in Cooum”, Black buck, Madras Natural History Society, Vol. III, No.384:12-19, 1987c.
  2. “Environmental Status of Adyar Creek - A Preliminary Report” Exnora Naturalists’ Club (ENC), Environmental Youth Service Programme (EYSP) from 15 to 31 May, 1997.
  3. Kothandaraman, H., S. Viswanathan and A. Kulasekaran, “A perspective study in River Cooum”, Seminar on River Cooum - “Let it be a resource”, pp. 4.3-4.10, University of Madras, 1986.
  4. Mudaliar, S. A., Abithana Chinthamani - The Encyclopaedia of Tamil Literature, pp. 101-103, Asian educational services, New Delhi, 1981.
  5. Rajamanickam, M., A critical study of Pathupattu, pp. 781, University of Madras, Madras, 1970.
  6. Rao, V.K., “ Health hazards of the Cooum river”, Seminar on River Cooum - Let it be a resource, pp. 8.1-8.14, University of Madras, 1986.
  7. Sanjeevaraj, P.J., “Eco-sensitive areas in need of protection”, Madras Musings, Vol. XII, No. 11, pp. 1 & 8., 2002.
  8. Sundaresan, B.B., “Cooum river - A resource”, “Seminar on River Cooum - Let it be a resource”, pp.1 – 7, University of Madras, June 14, 1986.
  9. Theodore Baskaran, S, “Death of an estuary”, The Hindu, January 12, 2003.

M. Amirthalingam
CPREEC

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