TEHRI HYDRO POWER COMPLEX (Tehri HPC)
THPC is a multipurpose scheme on river Bhagirathi, a tributary of river Ganges. It is designed for storing surplus water of river Bhagirathi during monsoon and releasing the stored water to fulfil the irrigation and drinking water needs of the population in the Gangetic plains of Uttarakhand and Uttar Pradesh during non-monsoon period while generating 2400MW of peaking power.
Tehri HPC consists of the following:
- Tehri Hydro Power Plant (Tehri HPP) - 1000 MW (4x250MW)
- Koteshwar Hydro Electric Project (Koteshwar HEP) - 400 MW (4x100MW)
- Tehri Pumped Storage Plant (Tehri PSP) - 1000 MW (4x250MW)
Tehri project was conceived in 1949 as a major storage scheme on River Bhagirathi and after investigations by Irrigation Department of Uttar Pradesh, cleared for implementation by Planning Commission in 1972. In the 1st Stage of Tehri HPC, Govt. of India approved the implementation of Tehri HPP in Mar’ 1994 along with committed works of Koteshwar HEP and essential works of Tehri PSP.
- Tehri HPP (1000MW)
It comprises of a 260.5m high earth & rockfill dam on river Bhagirathi at 1.5km downstream of its confluence with river Bhilangana. Dam is located in a narrow S-shaped valley with steep side slopes. Left abutment of the valley providing toe support to the dam.
Its Spillway system is comprising of Chute Spillway on right bank with 3 bays, 2 nos. Right Bank Shaft Spillways and 2 nos. Left Bank Shaft Spillways to bypass the surplus water during monsoon. It is designed to cater the probable maximum flood (PMF) discharge of 15540Cumecs corresponding to 1 in 10,000 years return period flood. The routed Design Discharge at PMF is 13043 Cumecs.
In addition to above an Intermediate Level Outlet (ILO) with discharge capacity of about 1125 cumecs at Full Reservoir Level (FRL) has been provided on the right bank at EL 700m to control the rate of filling during initial filling of reservoir and to deplete the reservoir below MDDL (EL 740m) during an emergency emerging as a result of some problem in dam or water crisis in the Gangetic plains of Uttarakhand and Uttar Pradesh.
Four head race tunnels of 8.5 m dia. each with intake at EL 720m and an underground power house on the left bank to accommodate four conventional type (Francis) generating units of 250 MW each.
All four units (Unit-IV towards I) were synchronized with the Northern Grid in July’ 2006, Oct’ 2006, Jan’ 2007 & Mar’ 2007 and are in commercial operation w.e.f. 22nd Sep’ 2006, 9th Nov’ 2006, 30th Mar’ 2007 & 9th July’ 2007 respectively.
Tehri HPP has become the landmark and pride of the Nation as a whole. Project is functioning well since commissioning not only fulfilled drinking and irrigation water requirements of the command area and much needed peaking power requirements of the Northern Grid but also mitigated floods during heavy rains in the year 2010, 2011 & 2013.
