North Lakhimpur: Several downstream areas of the Subansiri River in Assam’s Lakhimpur district were flooded on Monday after the National Hydroelectric Power Corporation (NHPC)-operated 2,000 MW Subansiri Lower Hydroelectric Project (SLHEP) at Gerukamukh released a large volume of water from the dam.
According to the District Disaster Management Authority (DDMA), Lakhimpur, the project released 12,057.24 cumecs of water at 10 am, which was categorised as a “High Discharge”. The discharge was 800.21 cumecs higher than the 11,275.03 cumecs released at 9 am.
DDMA data also showed high inflows into the Subansiri from Arunachal Pradesh, with 3,276.78 cumecs recorded at Daporijo (EWS-1) and 8,968.26 cumecs at Tamen (EWS-2) at 10 am.
NHPC had earlier stated that the Subansiri River could safely carry up to 7,000 cumecs of water, beyond which flooding in downstream areas was likely. Monday’s discharge exceeded that level by more than 5,000 cumecs.
Floodwaters entered villages including Ghunasuti, Naharani, Ghagar Kalakhowa and Sagalikota, affecting hundreds of residents. Water entered houses, forcing many families to move to raised stilt houses (chang ghars) and shift their belongings.
“The water level rose suddenly from around 7 am. The flash flood swept away our livestock and poultry,” a resident of Naharani village said.
The Lakhimpur district administration issued public announcements advising riverside residents to remain alert following the increase in the river’s water level.
According to officials, flooding affected 20 revenue villages in the Mohaijan area near North Lakhimpur. Authorities also warned of an increased risk of erosion in Na-Ali, Ghancharai, Tini Suti, Khoga and Jugalpur.
N. Mohammad, consultant to the Subansiri Lower Hydroelectric Project, said the higher discharge was due to increased inflows from the upstream catchment.
“The reservoir of the hydroelectric project is currently being maintained at 188 metres elevation because the project has not yet received permission from the National Dam Safety Authority (NDSA) to raise it to its designed storage level of 205 metres. The increased discharge is due to the higher volume of water entering the reservoir from the upstream Subansiri,” Mohammad said.
Authorities said they are monitoring the situation as continued rainfall in the upper catchment areas of Arunachal Pradesh may keep inflows high. Residents in downstream areas have been advised to remain alert and follow official advisories.