Landslide damages mega Subansiri hydroelectric project partially

way2barak, Oct 29 : The 2000 MW much delayed Lower Subansiri Hydroelectric Project, which is currently under construction at the border of Assam and Arunachal Pradesh, was partially damaged by a landslide, which also impacted the Subansiri River’s downstream flow, officials said on Saturday.

A senior NHPC (National Hydroelectric Power Corporation) official said, “One of the five diversion tunnels that was in use, diversion tunnel number 1, was blocked by a landslide on Friday at around 11:30 a.m.”

“After construction was finished, the other four diversion tunnel numbers were already blocked. Consequently, there is a significant decrease in the river flow downstream. The mean sea level at the dam spillway bay is 145 meters,” the official added.

According to him, the reservoir is holding on to its current 997cum/sec river flow, and its water level is rising. The water level rose to 139 meters at 1:00 p.m.

“By the evening, it is anticipated that the water level would have reached 145 meters, at which point the river will once again flow regularly over the spillway and downstream,” the official mentioned.

Notably, this is the second landslide that occurred at the same spot. The project was hit by a similar disaster in March.

The official said, “Since we work in the hills, incidents like these can arise from building activity. During the years while the building was underway, we also made advantage of the diversion tunnels.”

Meanwhile, Lakhimpur District Deputy Commissioner issued an advisory requesting the villagers residing in and around the bank of river Subansiri and adviced them to restrain themselves from activities like fishing, swimming, bathing, plying of boats etc. in the river water and not to venture in the river bed of Subansiri river during night hours under any circumstances to avert any kind of eventualities until return of normaley of the flowing water of the Subansiri river.

“The villagers may also be advised to keep their cattle’s like Cow, Goat, Mithun, Pig, Dog etc. away from the river to avoid any accident/loss thereof.

Moreover, people living in the downstream and low lying areas of Subansiri river are advised to remain alert and not to panic relying on messages transmitted from un-reliable and un- official sources,” the advisory said.

However, the NHPC officer asserted that the operation of the hydroelectric power project will begin on time. The project is expected to start in March 2024.

Many environmentalists are firmly opposed to hydropower projects in Arunachal Pradesh.

The Subansiri Lower Hydro Electric Project, which commenced the construction work in January 2005 after obtaining forest clearance in October 2004, faced multiple bottlenecks since its inception causing huge delay in commissioning the mega power plant.

The Hydro Electric Project, of which 90 per cent of the total work of the project has already been completed so far, would generate around 7,500 million units of power annually in “90 per cent dependable year”.

In January 2020, the cost of the giant power project, which was originally scheduled to be commissioned in December 2012, had escalated to around Rs 20,000 crore from the initial Rs 6,285 crore, the NHPC estimate stated.