Subansiri hydro project

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Context

• A massive landslide at NHPC's much-delayed 2,000 MW Subansiri hydro project along the Assam-Arunachal Pradesh border on Friday completely blocked the only functional diversion tunnel, thereby significantly obstructing water flow through the river.

About

• It is the largest hydroelectric project ever constructed in India.
• It is a run-of-river system on the Subansiri River.
• The project is located near North Lakhimpur on the Arunachal Pradesh-Assam border.
• Capacity: 2000 MW
• It will produce up to 7.4 billion kWh of electricity per year.

• The project includes the construction of a surface powerhouse and a 116m-high concrete gravity dam from the river bed level.
• The dam will be 284 meters long.
• The dam is in Assam's Dhemaji district, but the powerhouse is in Arunachal Pradesh's Subansiri district.
• The National Hydro Power Corporation (NHPC) is in charge of its development.

About the Subansiri Lower Hydroelectric Project (SLHEP):

• SLHEP is a gravity dam under construction (almost 90% of the work has been finished) with a capacity of 2000 MW (8x250 MW).
• It is India's largest hydroelectric project to date, and it is a run-of-river scheme on the Subansiri River.
• A run-of-river dam is one where the flow of water downstream of the dam equals the flow of water upstream of the dam.
• In other words, the dam does not hold/store water behind it; rather, it flows with the river.
• National Hydroelectric Power Corporation (NHPC) Limited is in charge of the SLHEP's construction.

Subansiri River

• The Subansiri River, sometimes known as the "Gold River," is the greatest tributary of the Upper Brahmaputra River.
• It originates in the Tibetan Himalayas and flows into India via Arunachal Pradesh (Miri Hills).
• It runs from the Himalayan Mountains to the east and south-east of Arunachal Pradesh before reaching the Assam Valley.
• Finally, it meets the Brahmaputra River in the Assam district of Lakhimpur.
• It meets the Brahmaputra in the mysterious confluence of Majuli Island, the world's largest populated river island.

Controversy regarding SLHEP

• The project has been stalled due to local agitation over several dam safety and administrative issues involved in its implementation, such as:
• SLHEP violates the 1980 Brahmaputra Board Act by transferring the work of the Subansiri Basin Water Resources Department from the Brahmaputra Board to the public and private sectors.
• There is also the question of rising seismic threat levels to the dam, according to IIT-Roorkee.

Other Contentious Dams

The Sardar Sarovar:

• The Sardar Sarovar Dam is a gravity dam on the Narmada River near Navagam, Gujarat.
• It is the world's second-largest concrete gravity dam by volume.
• The dam provides water and electricity to Gujarat, Madhya Pradesh, Maharashtra, and Rajasthan.
• The dam is said to have displaced over 2.5 lakh locals.

Mulla Periyar Dam:

• This gravity dam on the Periyar River in Kerala's Idukki district is owned and administered by the Tamil Nadu government.
• The height of the dam is a point of disagreement between the governments of Kerala and Tamil Nadu.

Polavaram project:

• It is a multi-purpose national project under construction on the Godavari River in Andhra Pradesh's West Godavari and East Godavari districts.
• Villages in Chhattisgarh and Odisha will be submerged as part of the project.

Kishanganga Hydroelectric Plant

• It is a run-of-the-river hydroelectric system in Jammu and Kashmir that is designed to move water from the Kishanganga River to a power plant in the Jhelum River basin.
• The World Bank's Court of Arbitration was unable to settle the dispute between India and Pakistan over the Indus water treaty.