Incessant rains for the last 48 hours in Lakhimpur and in the hills of neighbouring Arunachal Pradesh have resulted in the rise of the water levels of river Subansiri inundating many villages in Ghunasuti.
The swelling river waters have submerged several houses and agricultural lands in villages like Balibheta, Naharani, Uriamtola, Rowmari, Ujantoli, Gotoni and many others since Thursday.
People are panicked as the river is flowing past the under-construction 2000 MW Lower Subansiri Hydroelec Project site of the NHPC at Gerukamukh in great force.
It has been alleged that the overflowing river has breached the coffer dam at the project site of the NHPC with huge discharge causing floods in the downstream areas.
However, this has been denied by the NHPC authorities at Gerukamukh.
In a press release, the NHPC said no such coffer dam was constructed in the current working season upstream of Subansiri dam site.
It said the coffer dam was no more required to be constructed as the dam’s height has already attained levels much above the elevation of 125m last year.
NHPC also clarified that the dam is normally passing the river discharge through five diversion tunnels with a design capacity of 4550 cumec.
The discharge capacity of diversion tunnels was optimized considering the overall cost of the project and any flow in excess of the maximum capacity of diversion tunnels were designed to pass through the spillway bays, said the release.
“On August 26, 2021, the overflow started over dam spillways with the increase in the discharge of the order of about 9500 cumec, the overflow of about 3000 cumec from all the nine spillway blocks started in addition to the maximum discharge being passed through all the diversion tunnels.”
“All the dam structures and power house structures, coffer wall and diversion tunnels are absolutely safe and working properly,” said the NHPC press release.