Rapid Fire
Subansiri Lower Hydroelectric Project
- 27 Dec 2025
- 3 min read
The Union Minister of Power, Housing & Urban Affairs inaugurated the commercial operation of Unit–2 (250 MW) of the Subansiri Lower Hydroelectric Project.
- Subansiri Lower Hydroelectric Project: Approved in 2003, it is a run-of-the-river hydropower project with an installed capacity of 2000 MW, making it India’s largest hydropower project once fully commissioned.
- It is located at Gerukamukh on the Assam–Arunachal Pradesh border and is implemented by National Hydroelectric Power Corporation (NHPC) Limited.
- Geographic Significance: The project built on the Subansiri River, the largest tributary of the Brahmaputra, is strategically important for water management, flood control, and energy security in the North-East.
- It will supply power to 16 beneficiary states, provide free power to Arunachal Pradesh and Assam, and allocate 1,000 MW to the North-East, strengthening regional power availability.
- Dam and Flood Management: The project has a 116-metre-high concrete gravity dam, the largest dam in North-East India. As the first cascaded dam on the Subansiri River, it helps reduce downstream flooding by providing a flood cushion of 442 million cubic metres.
- The dam has a gross reservoir storage of 1,365 million cubic metres, and one-third of this storage is kept empty during the flood season to safely absorb excess water and protect downstream areas.
- Engineering and Technological Significance: The project features India’s heaviest hydro generator rotors, largest stators and inlet valves, and the first use of the Rotec Tower Belt system in dam concreting, marking a major advance in high-capacity hydropower engineering.
Subansiri River
- The Subansiri River (Chayul Chu in Tibet) is a trans-Himalayan river and the largest tributary of the Brahmaputra River.
- Originating in the Tibetan Himalayas, it enters India near Taksing in Arunachal Pradesh, flows through the Miri Hills, and joins the Brahmaputra in Assam at Jamurighat.
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