CHENNAI: A total of 165 water bodies including 31 lakes and 134 tanks have disappeared so far from the Pallikaranai catchment area, according to a report by Uvakai Research Foundation, an NGO, on Saturday.
Using historical revenue records from 1905 to the 1980s, satellite data, and Google Earth images, the study found that only 452 water bodies remain while 165 water bodies, including Velachery tank and Taramani lake, listed in the revenue records have been lost, resulting in a loss of 7.35 sq.km of water storage area. The Pallikaranai marsh has shrunk from 6,000 hectares in the 1920s to 694 hectares today, of which 225 acres is occupied by the Perungudi dump yard.
Unveiling the report on Pallikaranai catchment in the Kovalam basin, Dr E Vidhubala and N Udhayarajan, directors of Uvakai Research Foundation, urged the government to prioritise preserving existing water bodies for rainwater storage instead of draining it into the sea in the name of flood mitigation.
The Pallikaranai catchment, covering 306 sq.km, includes 28% of low-lying areas. Vidhubala demanded that these areas be designated as no-development zones due to their ecological importance and vulnerability to flooding. The findings are part of Volume 1 of “Chennai Waterscape Series - Hydrological Insights from the Pallikaranai Catchment in the Kovalam Basin.” The second volume, which will include field-level assessments and relevant recommendations, will be released in July.
Key Insights
If all water bodies & marshlands in Pallikaranai catchment areas are restored to 1.5m depth, up to 65% of rainwater runoff can be retained
Remaining 35% can be managed via natural channels like Okkiyam Madavu & B-Canal - if desilted & maintained
Pallikaranai Marsh reduced from 6,000 ha (1920s) to 694 ha today, with 225 acres occupied by Perungudi Dump Yard
Recommendations
Stop further encroachments and focus on reviving existing water bodies
Prioritise natural drains over new infrastructure like cut & cover drains or sponge parks
Collaborate with IIT & Anna University for scientific maintenance
Relocate the proposed Global Sports City at Semmencherry to protect vulnerable water bodies
Interdepartmental coordination along with ISRO to identify water bodies and maintain them