A landslide has damaged part of the under-construction 2000 MW Lower Subansiri Hydroelectric project in Arunachal Pradesh and Assam which has affected the flow in the Subansiri river downstream. The project is scheduled to begin operations from March 2024.

“Out of five diversion tunnels, only diversion tunnel number 1 in use, has been blocked due to landslide at about 11:30 am on Friday,” a senior official of NHPC (erstwhile National Hydroelectric Power Corporation) said.

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“The other four numbers of diversion tunnels had already been blocked earlier after construction works were complete. As a result, the river flow to the downstream is highly reduced. The dam spillway bay level is 145m mean sea level. The present river flow of 997cum/sec is being stored in the reservoir and water level of the reservoir is increasing. At 1 pm, the water level reached 139m. It is expected the water level to reach 145m by the evening and the river will again flow through the spillway to the downstream normally,” he added.

Interestingly this is the second landslide at the same location. A similar landslide impacted the project in March.

“We are working in the hills and construction activity can trigger such situations. We have also used the diversion tunnels for several years during construction activity. We believe that we can start operations in March as scheduled. This landslide will not cause any delay,” he added.

There is stiff resistance by environmental groups against hydropower projects in Arunachal Pradesh. HT reported in December last year that indigenous communities living downstream of the Dibang Multipurpose Project and proposed Etalin Hydropower Project in Arunachal Pradesh have raised concerns with a 2016 study of the Dibang sub basin in the Brahmaputra Valley, saying it has omitted assessment of impacts on areas immediately downstream of these projects.

The Cumulative Impact and Carrying Capacity Study, which was published in July 2016 and accepted by the Union environment ministry, is guiding the Centre to take a call on the 3,097 MW Etalin Hydropower Project and 16 smaller hydro projects planned in the region.

by hindustantimes