Chennai braces for flood as Adyar level rises, canals flow in full capacity

Five years after overflowing Chembarambakkam reservoir triggered an unprecedented deluge in Chennai city and surrounding areas, causing large-scale destruction to lives and properties, the sluice gates of the reservoir were opened again on Wednesday, releasing 1,000 cusecs (cubic feet per second) initially, which was increased to 5,000 cusecs at 7.00 pm as the inflow increased.
As the city braces for cyclone Nivar, the state administration is doing everything possible to keep the reservoir levels under check – at 22 ft against a reservoir capacity of 24 feet – to prevent a repeat of 2015 floods, when Chennai residents were taken by surprise as about one lakh cusecs flowed into Adyar river from various sources, against its carrying capacity of 60,000 cusecs. If the outflow is maintained at 5,000 cusecs, the reservoir would be releasing more than 12,000 million litres per day – equivalent to 15 days of drinking water supply in the city - into Adyar.
Chief minister Edappadi K Palaniswami inspected the reservoir during the course of the day along with experts from PWD and Metrowater departments. The CM said the entire additional inflow into the reservoir would be released into the river to avoid the reservoir crossing the 22 feet mark.
“Water was released from the reservoir when the dam level touched 22 feet and the inflow was 4,398 cusecs. Usually during a cyclone, rainfall reduces and wind speed increases. The maximum release from the reservoir may not cross 10,000 cusecs,” said S Asokan, chief engineer, public works department. Another 2,000 cusecs is being released from Adhanur tank, which also flows into Adyar. The PWD had also widened the river and removed silt to ensure free flow of water in the river.
Greater Chennai Corporation, meanwhile, is engaged in evacuating people from the river banks, slums and other low-lying areas to rescue camps. More than 2,700 people have been shifted from Adyar basin to relief camps. Public address systems are being used to inform people about the impending danger if they stay put in their houses.
The Union Jal Shakti ministry said Poondi in river Kosasthalaiyar basin was also likely to get an average inflow of 3,885 cusecs by Thursday morning.
Activists have alleged mis-governance and red tape in clearing water body restoration projects. “The government had passed work orders to desilt all four city reservoirs in 2018. Work on Chembarambakkam reservoir to remove 1.51cr cubic feet of silt should have begun in December 2018. However, work began only in June 2019 and soon due to south west monsoon it was stalled. If that work had been completed, the reservoir’s capacity would have increased by 0.5 TMCft,” said S Thirunavukkarasu, retired PWD official.
Alarm bells were raised when water level in Adyar began rising by evening. “The problem is that Adyar, Cooum, Buckhingam Canal, Mambalam canal, Virughambakkam canal, MGR canal and most feeder canals are flowing in full capacity. And due to this, even the water carried by the storm water drains was hitting a reverse flow, inundating city roads and localities. We have to wait for the tide to reduce in the sea,” said a corporation official.