Andhra Pradesh

‘Amaravati needs design elements to avert a Chennai-like deluge’

After the recent Chennai deluge due to high-intensity precipitation and freak floods, experts want the Andhra Pradesh government to be cautious and incorporate appropriate design elements while constructing Amaravati, to protect it from havoc caused by floods.

The suggestion comes in the light of the latest report of the United Nations that south India, in particular, is prone to natural vagaries like frequent floods.

“What used to be a once-in-100-year event can now happen once in 20 years. Certain areas will have 50 per cent more rain than noticed before. Krishna and Godavari basins are included in the forecast for 2000 to 2040,” said former Engineer-in-Chief of Andhra Pradesh and United Nations consultant T. Hanumantha Rao.

“We had already observed a sequence of this in the 2009 floods in Srisailam, which experienced the maximum flood discharge of 10.6 lakh cusecs for Krishna in Vijayawada. The Srisailam reservoir received 24 lakh cusecs, proving a high-intensity precipitation due to climate change,” he added. “Mumbai in 2005 witnessed a rainfall of 940 mm in a single day and not to forget the Uttarakhand deluge of 2013. They are all instances of global warming forecast coming through,” Mr. Rao said.

Interestingly, in 2009, water did not come from high rainfall regions like Western Ghats but from drought-prone areas down below Alamatti and Tungabhadra dams. The area between Nagarjunasagar, Amaravati and parts of Prakasam district is similar to area of catchment in 2009 which received high precipitation.

“If such freak incidents of 24 lakh cusecs discharge came to Amaravati, what will be the scenario?” Mr. Rao wondered and wanted the government to remain prepared.

“One has to work out to what height water level goes up. The National Institute of Hydrology, Rourkee, could be asked to work out the mathematical models. My guess is it will be 10 to 15 ft higher than previously received,” he said. For 10.6 lakh cusecs discharge, Amaravati road preciously received a level of five-feet and a depth of five feet in land.

If the discharge is over and above 24 lakh cusecs due to floods in Krishna, then the level will be another 10 to 15 feet.

“We have to be prepared for it along the Krishna river. To find out as to what extent the submersion will be, it will take around six months to conduct 3D hydraulic model studies for assessing the depths of submersion for varied discharge at various places. It is prudent to get these studies done and take precautions to reduce the impact of such freak floods and intense rain. What if both events happen together?” he asked.

The area between Nagarjunasagar, Amaravati and parts of Prakasam district is similar to area of catchment in 2009 which received high precipitation

T. Hanumantha Rao

Former Engineer-in-Chief

of Andhra Pradesh

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Printable version | Oct 29, 2020 10:09:18 AM |

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