Shrinking waterbodies, floods become 2 sides of same coin

The role of waterbodies in the urban ecosystem becomes even more critical as the city faces the challenge flood every monsoon, as a result of rapid unplanned urbanisation. But their numbers are declining rapidly. More than 10 tanks have gone missing from North Chennai alone. Experts said it would take at least 10 years to revive them.

“North Chennai was badly impacted in the recent monsoon because of these missing tanks. Besides these, 20 lakes have also disappeared. For instance, The Dr Ambedkar Arts College and housing quarters were built on the Vyasarpadi lake. The Ayanavaram lake disappeared 50 years ago,” said S Thirunavukarasu, retired PWD assistant executive engineer.

Experts said surplus water from tanks used to flow into Cooum river, Otteri Nullah and Buckingham canal. Over time, buildings came up on Otteri Nullah and it shrunk in size. If there were no encroachments in Otteri Nullah, it could have carried 3,500 cusecs of water this past monsoon. “Removing encroachments and restoring waterbodies are the only solution to prevent flooding, which would take at least 10 years. Currently, PWD officials are taking steps to safeguard the existing lakes. They are not bothered about the missing ones yet,” said Thirunavukarasu.

“Kodugaiyur lake was one of the largest waterbodies in and around the city. In the early 1980s, the Tamil Nadu Housing Board (TNHB) took over the lake and constructed quarters on it. Even, Ennore Thermal Station was built on a lake in 1970s. Kosasthalaiyar river has also fallen prey to encroachers.

However, the recent inundation in North Chennai was a combination of both poor urban planning and climate change,” said Pooja Kumar, an environmentalist.

When contacted, a senior official of the Water Resources Department said they don’t have a list of missing waterbodies and they are now restoring the existing lakes. If they get orders to restore the missing lakes or tanks, steps will be taken immediately.