In meteorological parlance, “very heavy rain” means 12.4cm to 24.4cm, but Chennai and nearby districts were pounded by almost twice that, he said in a statement on Sunday. The reservoir received about 2.13 thousand million cubic feet of water in 24 hours (ending at noon on December 2) – 60% of reservoir’s capacity. Hence, advanced lowering of reservoir level would have made little difference, he said.
On December 9, TOI was the first to say that officials could have anticipated the heavy rain and released water proactively. Gnanadesikan disputed reports that NASA had put out a 50cm forecast, saying “NASA has said they do not predict rainfall.”
But the chief secretary did not explain why the government ignored BBC’s weather warning of 50cm rainfall. Also, the state went into December with a forecast of very heavy rainfall after passing through the wettest-ever November in 100 years. Yet officials chose to go by the book and increased water release only on December 1, after incessant rains the previous night.