Subansiri Lower Dam

The Subansiri Lower Dam, officially named Subansiri Lower Hydroelectric Project, is an under construction gravity dam on the Subansiri River in NorthEastern India. It is located 2.3km upstream of Gerukamukh village in Dhemaji District and Lower Subansiri District on the border of Assam and Arunachal Pradesh states. Described as a run-of-the-river project by NHPC Limited, the Project is expected to supply 2,000 MW of power when completed. The project has experienced several problems during construction to include landslides, re-design and opposition. It was expected to be complete in 2018. It is notable that, if completed as planned, it will be the largest hydroelectric project in India.DesignThe concrete gravity dam is designed to be 116m tall, measured from the river bed and130m from foundation. Its length will be 284m and the dam will have a structural volume of 2250000m3. The reservoir created by the dam will have a gross storage capacity of 1.37km3, of which.44km3 can be used for power generation or irrigation. At normal level, the reservoir's surface will cover 33.5km2. The surface powerhouse, located on the left bank, will contain eight 250 MW Francis turbine generators.There will be eight horse shoe shaped head race tunnels, each being 9.5m in diameter and having a length from 608-. There will be eight horse Shoe shaped surge tunnels, each being 9.5m in diameter and having length from 400-. There will be eight horse shoe/circular shaped penstocks with varying diameters of 7- and lengths of168-. The tail race channel, which will transfer water discharged by the turbines back to the river, is 206m wide and 35m long.