Chennai has 2,950 km of drains, most of which have an inadequate handling capacity
Reportedly ten days after Cyclone Michuang brought more than 50 cm of rain inundating many parts of chennai, a senior official of Greater chennai Corporation said the city needs to add at least 2,000 km more of modern storm water drains with a higher capacity to handle showers of this magnitude. The city currently has around 2,950 km of drains, most of which have an inadequate handling capacity of 2-5 cm per hour, S Rajendiran, GCC chief engineer for storm water drains (SWD), told PTI.He said “Chennai has a road length of 5,500 km. At least 5,000 km of drains with higher capacity are required for the city to handle such heavy rains. New drains coming up in the northern, western and southern parts of the city are being built to handle rain precipitation of 7-8 cm/hour”. The official was referring to the 767 km of drains being constructed at a cost of Rs 3,520 crore in Kosasthalaiyar river basin (North and West Chennai) and 360 km of drains built in Kovalam river basin (South Chennai) at Rs 1,715 crore.Since 2021, the GCC has demolished around 100 km of older drains to improve their carrying capacity from 2-5 cm/hour to 8 cm/hour based on inputs by the Thirupugazh committee and the IIT-Madras, Rajendiran said. The committee was appointed by the DMK government in 2021 to advise on mitigation and flood management in Chennai. “In these localities (Chennai city), we noticed that water was able to drain much faster,” he said, adding that the civic body has built around 900 km of drains since 2021.When responding to a question about inundation in areas with storm water drains, Rajendiran blamed a combination of factors across different parts of the city, including overflowing canals and rivers and a high tide at the sea. The GCC’s action plan for these localities will be focussed on desilting water bodies to increase its water retention capacity, erecting solid bunds and building canals to have a defined path for overflowing water. “This will draw on the success of restoration of 210 waterbodies in the city which absorbed the impact of heavy rainfall this year,” Rajendiran said.