Lower Subansiri Hydroelectric Power Project

1 min read
Lower Subansiri Hydroelectric Power Project Blog Image


Assam's Lower Subansiri Hydro Electric Power project recently faced a critical setback as a major landslide completely blocked its only functional diversion tunnel, thereby significantly obstructing water flow through the river.

About Lower Subansiri Hydroelectric Power Project

  • It is the biggest hydroelectric project undertaken in India so far.
  • It is a run-of-river scheme on the river Subansiri.
  • Location: The Project is located near North Lakhimpur on the border of Arunachal Pradesh and Assam.
  • Capacity: 2000MW
  • It will generate up to 7.4 billion kWh of electricity annually.
  • The project includes the construction of a surface powerhouse and a concrete gravity dam that is 116m-high from the river bed level.
  • The length of the dam will be 284m.
  • The dam is located in the Dhemaji district of Assam, while the powerhouse is located in the Subansiri district of Arunachal Pradesh.
  • It is being developed by the state-run National Hydro Power Corporation (NHPC).
  • Funding:
    • The project cost was met through 70% equity and 30% debt financing through the provision of a term loan.
    • The central government is providing budgetary support as part of the equity component.

Key facts about the Subansiri River

  • Subansiri River, better known as the "Gold River" is the largest tributary of the Brahmaputra River.
  • It flows through Assam, Arunachal Pradesh, and the Tibet Autonomous Region of China. 
  • Course:
    • Originating from the Himalaya Mountains, it flows towards the east and south-east portion of Arunachal Pradesh and then flows to Assam Valley.
    • Finally, it joins the Brahmaputra River in Lakhimpur district, Assam.
  • It joins the Brahmaputra at the mystic confluence of Majuli Island, which is noted as the largest inhabited river island in the world.
  • Total Length: 442 kilometres

Q1) What is a Gravity Dam?

A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by primarily utilizing the weight of the material alone to resist the horizontal pressure of water pushing against it.

Source: Landslide blocks diversion tunnel at NHPC's Subansiri hydro project