Latest Update on the Lower Subansiri Hydroelectric Project

The National Hydro Power Corporation (NHPC) has raised concerns regarding potential downstream effects in Assam as it prepares to begin electricity generation from the 2000 MW Lower Subansiri Hydroelectric Project (LSHP).

Overview of the Lower Subansiri Hydroelectric Project

• The project is a 2000 MW run-of-the-river hydroelectric facility located on the Subansiri River, a tributary of the Brahmaputra, straddling the border of Arunachal Pradesh and Assam.
• Upon completion, it will be the largest hydroelectric power station in India.
• The project is being developed by NHPC, a state-owned corporation.

Key Features of the Lower Subansiri Hydroelectric Project

• The project will feature a concrete gravity dam, which will rise 116 meters from the riverbed and 130 meters from its foundation, with a total length of 284 meters. The reservoir will have a gross storage capacity of 1.37 cubic kilometers.
• The powerhouse will be equipped with eight 250 MW Francis turbines, situated on the left bank of the river’s surface.
• Additional infrastructure includes eight horseshoe-shaped headrace tunnels (ranging in diameter from 9.5 meters, with lengths between 608 and 1,168 meters), eight surge tunnels (with diameters of 9.5 meters and lengths between 400 and 485 meters), and eight circular penstocks (ranging in diameter from 400 meters to 485 meters, and lengths from 7 meters to 9.5 meters).
• A tailrace channel, measuring 35 meters in length and 206 meters in width, will return water discharged by the turbines to the river.