Why in news?
Construction on the Dibang Multipurpose Project in Arunachal Pradesh reached an important milestone on 17 February 2026: engineers achieved “daylighting” of Diversion Tunnel‑3. This means that the tunnel has been excavated from one end to the other, allowing light to travel through. The success marks steady progress on India’s largest planned hydropower project.
Background
The Dibang Multipurpose Project, being developed by NHPC Limited, is located on the Dibang River, a tributary of the Brahmaputra. When completed, it will have an installed capacity of 2,880 megawatts. Apart from generating electricity, the project includes flood control and water supply components. Work began in 2019 and the project involves constructing a 278 metre‑high concrete gravity dam – one of the tallest of its kind.
Key details
- Diversion tunnels: To build a dam across a river, engineers dig tunnels to divert water away from the construction site. The Dibang project has four such tunnels. Daylighting Tunnel‑3 indicates that excavation has reached the downstream end.
- Project size: With a capacity of 2,880 MW and a planned 278 m dam, it will be India’s largest hydropower facility and the highest concrete gravity dam in the world when finished.
- Economic and strategic importance: The project will supply electricity to the national grid, assist in flood control in the Brahmaputra basin and support regional development in Arunachal Pradesh.
Challenges and future steps
Large hydropower projects require careful management of environmental and social impacts. Construction activities must ensure the safety of local communities and the protection of biodiversity. As work continues, NHPC and government agencies will need to monitor environmental flows, rehabilitate affected villagers and address concerns of downstream states. Successful completion of diversion tunnels brings the project closer to the next phases of dam construction and eventual power generation.
Source: NET
