Context: The long-delayed Subansiri Lower Hydroelectric Project on the border of Arunachal Pradesh and Assam suffered its latest setback after a large part of the hill collapsed into its reservoir. The deposits blocked the only functional diversion tunnel and stopped the flow of water downstream of the dam into the Subansiri River, a major tributary of the Brahmaputra.
- The Subansiri River has its origin in Tibet, and it is an antecedent river.
- It enters India near the town of Taksing (Arunachal Pradesh) and flows east and southeast through Miri Hills, then south to the Assam Valley at Dulangmukh in Dhemaji district, where it joins the Brahmaputra River at Jamurighat in Lakhimpur district.
- Small tributaries of the Subansiri include Rangandi, Dikrong and Kamala.
- The Subansiri lends its name to two districts in Arunachal Pradesh: Upper Subansiri and Lower Subansiri.
- The high topographic variation makes this river a potential zone for harnessing it for hydropower. The districts situated on the bank of the Subansiri River are flood prone during monsoon season.
- The Subansiri River is the largest tributary of the Brahmaputra River.
Subansiri Lower Hydroelectric Project
- Location: Located on the Subansiri River, which is on the border of India’s two north-eastern states, Arunachal Pradesh and Assam.
- Capacity: 2,000MW.
- Developing Agency: The project is being developed by the state-run National Hydro Power Corporation (NHPC).
- Delays: The construction of Lower Subansiri started in 2005 and was due to be completed in 2010. However, the project was delayed due to stiff opposition over its potential environmental impact.
- Present Status (2023) – As per the Ministry of Power, 90% of the total work of the project has been completed.