The Tamil Nadu government said on Sunday the recent floods in Chennai were not because of any delay in taking a decision about releasing water from the Chembarambakkam lake into the Adyar river.

Responding to media reports on this, Tamil Nadu Chief Secretary K Gnanadesikan said the flooding was caused by heavy rains in Chennai, Kanchipuram and Tiruvallur districts.

He said the India Meteorological Department on November 30 and December 1, 2015 issued advisories of isolated, heavy rainfall and not 50 cm rainfall as reported in a section of media.

Gnanadesikan said ‘isolated’ in meteorological terminology means only in one or two places, while ‘heavy’ rainfall is between 6.4 cm and 12.4 cm, and ‘very heavy’ means rains between 12.4 cm and 24.4 cm.

He dismissed reports that engineers at Chembarambakkam were waiting for instructions from higher authorities as ‘malicious’.

According to rules, water should be maintained at 2 ft below the ‘full tank level’ while the monsoon is still active.

Gnanadesikan also said adequate flood warnings were issued to the people living in low areas on December 1, and 47,300 people were evacuated from there.

“The flow in Adyar river reached its full capacity due to the surplus water from Chembarambakkam tank, the inflow from the catchment areas of Adyar within Chennai city and the surplus received from the other tanks,” he said.

“In view of the heavy flow in the Adyar river, the high intensity runoff of local rainfall in Chennai city and adjoining urban areas could not fully drain into the Adyar and hence contributed to the inundation of the city,” Gnanadesikan said.

Image: Army personnel rescuing people from a flooded locality in Chennai on Thursday after heavy rainfall. Photograph: PTI