The unusual floods in the Krishna and Tungabhadra basins bring out the frailty of man vs nature and man in society. First, let’s get some frail ideas out of the way. Consider: the flow in an ordinary Yamuna flood can be around 44,000 cusecs. So when the water accumulation leads to 20 lakh-plus cusecs you are talking of a one-in-a-10,000-year flood. Nobody has measured such a flood, because even five hundred years ago there were no such measurements — so hydrologists extrapolated recorded experience to measure extreme behaviour. Some have claimed the network of dams led to the floods. They’re all wet. Even in the mid-’90s Andhra wanted the Almatti dam to be kept at a lower height, so that they would get more water downstream, and flood control was the argument for the present height. A smaller dam would have made matters worse, for it would have stored less flood water which would have caused more damage in Andhra. That the Andhra engineers should have kept empty capacity to accommodate the flow is a worse argument and bringing in the Surat collapse is a non-sequitur. In the Deccan plateau we always try to operate dams in a way that by mid-September we get a full tank. That way we get maximum water in the Rabi and summer. Of course, they didn’t anticipate a one-in-a-10,000-year flood in design. (The Sardar Sarovar Dam was planned for a one-in-a-1000-year flood and then they said it wasn’t enough so we redesigned it for a one-in-a-10,000-year flood. Then some nitwit said do it for a one-in-1,00,000-year flood. It turns out Gujarat wouldn’t exist then so the dam at least wouldn’t be the problem.)

... contd.