The drought-prone and arid districts of Ramanathapuram, Pudukottai, Sivaganga and Villupuram in the State have a very good distribution of wetlands.

The National Wetland Atlas, prepared by the Ahmedabad-based Space Applications Centre (SAC) of the Indian Space Research Organisation (ISRO), has classified Puducherry and Tamil Nadu as wetland-rich States as they have 12.88 per cent and 6.92 per cent of geographic area under wetlands respectively.

Lakshadweep leads with 96.12 per cent of its geographic area under wetlands, followed by Andaman & Nicobar Islands (18.52%), Daman & Diu (18.46%) and Gujarat (17.56%).

In Tamil Nadu, wetlands occupy as high as 18.05 per cent of the geographic area in Ramanathapuram and as low as 1.08 per cent in Coimbatore.

In terms of total wetland area, Kancheepuram is the leading district with 80,445 hectares (8.91%) and Chennai has the smallest area, 917 ha (0.10%).

While Ramanathapuram and Pudukottai have over 70,000 ha as total wetland area, Sivaganga and Villupuram have over 60,000 ha and Tiruvannamalai and Nagapatinam districts have a wetland area of over 50,000 ha.

Lake/pond and tank/pond are the dominant wetland types found in all the districts, accounting for 61 per cent. About 4,369 natural lakes and ponds have a total wetland area of 3.16 lakh ha. And there are 19,343 man-made tanks and ponds with a total wetland area of 2.37 lakh ha. Pudukottai district has the highest area under lake/pond (38,966 ha) as well as tank/pond (26,419 ha). Most of the major lakes and tanks were created during the rule of monarchs.

Only small tanks and percolation ponds have been created in the post-Independence era.

In coastal areas, lagoons, inter-tidal mudflats and salt pans are the dominating wetland types.

Lagoons are observed in eight districts, with Tiruvallur leading in terms of area. Salem district leads in area under reservoir/barrage. While mangrove type has been observed in 11 districts, coral reef is restricted to Ramanathapuram and Tuticorin. Point Calimere Wildlife and Bird Sanctuary has been cited as an important wetland of the country in the atlas.

“The objective of the atlas is to protect the wetlands. Due to development and population pressure, wetlands are being slowly encroached upon, especially in urban areas, to facilitate infrastructure and housing needs. The atlas will help the government to identify and protect wetlands,” says Prof. M. Ramalingam, Director, Institute of Remote Sensing, Anna University.

The institute was part of the team of the centres that assisted the SAC team led by Sushma Panigrahy in preparing the wetland atlas which was sponsored by the Ministry of Environment and Forests.