The 2000 MW 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.”
However, the 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.