The Tamil Nadu government said on Sunday that it can't be blamed for the massive flooding of Chennai following the heaviest rains in a century.
Chief Secretary K. Gnanadesikan denied that official indecision or mismanagement vis-a-vis the release of water from the Chembarambakkam lake into the Adyar river caused the all-round destruction.
He said in a statement that the floods were caused primarily due to the very high rainfall in November, which was followed by more rains in Chennai, Kanchipuram and Tiruvallur districts on December 1.
Media reports have said flooding of the Adyar that killed many and destroyed livelihood and assets of millions of people was due to improper management of water releases from the Chembarambakkam lake.
Gnanadesikan said the India Meteorological Department (IMD) on November 30 and December 1 had issued advisories of isolated heavy rainfall and not 50 cm rainfall as reported by some media groups.
He said that in meteorological terminology, 'isolated' means only in one or two places, heavy rainfall is between 6.4 cm to 12.4 cm while very heavy rain stands for 12.4 cm to 24.4 cm of rainfall.
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He dismissed as "malicious" and "canards" allegations that engineers at the lake waited for instructions from the principal secretary of the Public Works Department and the chief secretary and the imputation that the officers were waiting to be ordered by Chief Minister J. Jayalalithaa.
According to Gnanadesikan, the level of water reservoirs required to be maintained at two feet below full tank level while monsoon is still active.
He said the rules balance the interests of water storage for the scarcity period, the need to control flooding in downstream areas and the safety of the reservoir.
Gnanadesikan said adequate flood warnings were issued to people living in low lying areas on December 1, and over 47,300 people were evacuated.
He said many tanks were breached due to heavy rains and the water flowed into the Adyar river which flows through Chennai.
"The flow in Adyar reached its full capacity due to the surplus from Chembarambakkam tank, the inflow from the catchment areas of Adyar within Chennai and the surplus received from the other tanks," he said.
"In view of the heavy flow in the Adyar, the high intensity runoff of local rainfall in Chennai and adjoining urban areas could not fully drain into the Adyar and hence contributed to the inundation of the city."
The Tamil Nadu floods have killed nearly 350 people in four districts including Chennai and caused widespread destruction.