TEHRI DAM & HPP(STAGE-I)

  • 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:
    1. Tehri Hydro Power Plant (Tehri HPP) - 1000 MW (4x250MW)
    2. Koteshwar Hydro Electric Project (Koteshwar HEP) - 400 MW (4x100MW)
    3. 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.
     
    1. 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 13043Cumecs.

    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.
  • SALIENT FEATURES
     
    Nature of Scheme:Storage scheme
    Hydrology
    Normal Annual Rainfall    1016  to 2630 mm.
    Maximum recorded flood discharge   3800   Cumecs
    Adopted maximum flood for diversion during monsoon period 8120   Cumecs
    Probable maximum flood   15540  Cumecs
    Routed Flood  13040  Cumecs
    Reservoir
    Full Reservoir Level   (FRL)EL  830 m.
    Maximum Level during design flood (MFL) EL   835 m
    Dead Storage Level EL   740 m.
    Gross Storage 3540 MCM
    Dead Storage925 MCM
    Live Storage 2615  MCM
    Water Spread at full Reservoir Level EL.830 m.44 Sq.km.
    Water Spread at dead Storage Level EL.740 m.   18 Sq.km.

    TECHNICAL FEATURES
    Diversion Tunnels
    Type   Horse shoe
    Left Bank 2 Nos. 11.0m dia, 1774 &1778 m long
    Right Bank2 Nos. 11.0m dia, 1298 &1429 m long
    Diversion Flood Discharge 8120 Cumecs
    Dam
    Type Earth and Rock fill dam
    Top Level    EL 839.5 m
    Height 260.5 m
    Width at riverbed  1125 m
    Width at top 25.5 m flared to 30.5 m at abutments 
     Length at Top 575m
    Slope 
    Upstream 1: 2.5  
    Downstream 1: 2  
    Spillways
    Chute Spillway:   
    Crest Level EL 815.0 m
    Waterway                                                                  3 bays of 10.5 m width
    Design Discharge   5500 Cumecs
    Type & No. of GatesRadial Gates, 3 Nos
    Right Bank Shaft Spillway: 
    Type                                                                          Ungated  2 Nos
    Crest Level  EL 830.2 m
    Dia of Shaft  12.0 m
    Design Discharge 3850 Cumecs
    Left Bank Shaft Spillway:   
    Type Gated 2 Nos
    Crest Level  EL 815.0 m
    Dia of Shaft 12.0 m
    Design Discharge3650 Cumecs
    Type of GatesRadial gates
    Intermediate Level Outlet:  
    No. and size One; 8.5 m dia
    Discharge capacity ( at EL. 830.0 m) 1100 Cumecs
    Intake Works:  
    Location Left Bank of river Bhagirathi
    No & Type of Structure2 Nos. Submerged Structure
    Crest ElevationEL 720 m.
    Head Race Tunnels: 
    Size and Number8.5m. dia, 2 Nos, 
    Total Length1634 m
    Penstocks: 
    Number and Size4 Nos., 5.75 m. dia each
    Total Length1040 m
    Power House
    Machine Hall:  
    Type Underground
    LocationLeft Bank, under ground
    Number & Units4 Nos, 250 MW each
    Size197 m long, 22.0 m wide, 47.2m. high
    Head Maximum 231.5 m ,
    Minimum 127.50 m ,
    Design     188.0 m.
    Transformer Hall: 
    TypeUnderground
    Size161m.long X 18.5m.wide X 29.0m high
    Step-up Transformers: 
    Capacity306 MVA
    Number 4
    Voltage Ratio15.7/400 KV
    Switchyard: 
    Location and TypeIndoor SF-6 Switchgear
    Tail Race Works: 
    Number and size of tail race tunnels2 Nos. , 9.0 m. dia  each
    Length of Tunnels 862.5 m & 747.5 m
    Invert Level of TRT OutletEL. 603.0 m.
    Installed Capacity :1000 MW (4x250 MW)
     
  • Benefits from the Tehri Hydro Power Complex
    ·         Addition to the installed generating capacity in the Northern Region 
    (1000 MW on completion of Tehri Stage-I)
     
    2400 MW
    • Annual energy availability (Peaking)
      (2797 MU on completion of Tehri Stage-I)
    5220 MU
    • Irrigation (additional)
    2.70 Lac.ha.
    • Stabilisation of existing irrigation
      (besides above)
    6.04 Lac.ha.
    • Additional Generation in downstream Projects
    200 MU
    • 300 Cusecs (162 million gallons per day) of drinking water for Delhi which will meet the requirements of about 40 lac people.
    • In addition, 200 Cusecs (108 million gallons per day) of drinking water for towns and villages of U.P. which will meet the requirement of 30 Lac people.
    • Flood Moderation
    ·         Integrated development of Garhwal region, including construction of a new hill station town with provision of all civic facilities; improved communication, education, health, tourism, development of horticultures, fisheries, and afforestation of the region.
     




Updated on : 03/03/2022