The flood in Chennai on December 1 was the rarest of rare natural calamity and was not caused by any failure in the management of water release from reservoirs, said K. Gnanadesikan, Tamil Nadu Chief Secretary, here on Sunday.
In a statement, he said the flooding was caused primarily due to the very heavy rainfall in November, the second highest recorded in more than 100 years, followed by high intensity of rainfall in Chennai, Kancheepuram and Tiruvallur districts.
“Reports in sections of the media of overflow from Chembarambakkam tank after it reached its full capacity of 24 feet are factually incorrect. The entire discharge was through the regulators and there was no uncontrolled discharge through surplus weirs.”
The reservoir received about 2.13 tmcft of water in a span of 24 hours from December 1 noon which was about 60 per cent of its capacity. Hence, no significant difference would have been made from the flood control perspective by lowering the level below 22 feet, he said, pointing to reports that the water level should have been kept at 75 per cent instead of 86 per cent as was done.
The tank accounted for only 44 per cent of the Adyar’s catchment. Due to heavy rain of 47 cm at Mudichur, Tambaram and Tiruneermalai areas and the surplus from several tanks, the Adyar river carried a huge flow downstream of the confluence point of the Chembarambakkam tank surplus, he pointed out.
Prior intimation of the water release, including step up of release, was given by an Assistant Engineer, who is the controlling officer of the Chembarambakkam lake, to the Chennai and Kancheepuram Collectors, Chennai Police and Corporation Commissioners asking them to take all necessary precautionary measures.
Flood warnings were given. It was telecast in major television channels.
After the second warning, nearly 30,000 people had been evacuated from low-lying areas. The allegation that the government had not given sufficient alert to the people was not true, he said. As heavy rain was forecast, supervisory officers, including the Chief Engineer, Chennai Region of Water Resources Organisation, Public Works Department, were also present at the Chembarambakkam tank, personally monitoring the situation.
Closely watching the inflows and the rainfall upstream, the engineers regulated the discharge from the tank .
“No specific instructions or orders are required nor were they sought from the Principal Secretary, PWD or the Chief Secretary for release of surplus water from the Chembarambakkam tank in the period leading up to December 1,” he clarified..
