Hydro Disaster

April 2023: Another Landslide at Lower Subansiri HEP

(Screengrab of India Today North East video report on landslide at Lower Subansiri HEP site on April 03, 2023)

The site of Lower Subansiri Hydroelectric Power (HEP) has witnessed another massive landslide on April 3, 2022. The 2000 MW project is being developed by NHPC Ltd at Gerukamukh bordering Assam and Arunachal Pradesh.

As per North East India 24 report, the landslide triggered by rainfall has caused damage in the main part of the dam and the workers had to be evacuated to a safe place. No human casualty has been reported from the incident.

“A large part of the hill, made of soft, sedimentary rock, located at the left bank of the river Subansiri, slid down heavily and violently in the river basin by producing a robust sound and affecting the Diversion Tunnels of the project adversely. The proportion of the landslide was so heavy that it produced big waves in the river basin by raising the water up to several meter height” reads North East Now report.

A huge landslide had occurred at same place in October 2022 and the latest visuals suggest its turning into chronic landslip zone.

However, Vipin Gupta, project’s executive director has denied the landslide causing any damage to the project. He claimed some portion of overhanging hills that they were planning to remove by blasts have fallen off by itself during rains as mentioned in The Indian Express report.

The location is above the diversion tunnels, four of which we have already blocked and the remaining one will be done so within two months, the NHPC official said, reports the East Mojo.

Another report by The Indian Express mentions that the “Central Electricity Authority (CEA) in April 2022 had advised the NHPC to engage a specialized agency to examine the strength of the project’s powerhouse retention wall and also assess the impact of diversion tunnels on the site’s slope stability before the onset of monsoon”. However, the studies were not carried out. The report also lists the landslide incidents at project site since beginning of the project work in 2005.   

In this November 2022 blog, SANDRP has compiled at least 5 flash floods, 6 landslides and 3 accidents at the project sites killing 5 workers since May 2022. This time lapse animation by Planet Lab images also tracks slope failures and landslides at the project site from 2009-2022.

While the controversial project site has been facing repeated disasters, the indifferent NHPC continues to underplay the safety concerns and ignore the frequent warnings.

Bhim Singh Rawat (bhim.sandrp@gmail.com)

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