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1
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General
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Project name
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Betan Karnali PROR Hydroelectric Project
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Location
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Surkhet District, Karnali Province & Achham District, Sudurpashchim Province
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Co-ordinates of the Project area
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28o50’57” N to 28o 56’04” N latitude,
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81o11’43” E to 81o 24’42” E longitude
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Nearest highway
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Karnali highway
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Nearest airport
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Surkhet airport- 94.25 km from project site
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Nepalgunj airport – 200.25 km from project site
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River
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Karnali
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Climate
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Moderate
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Type of project
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Peaking Run-of-River (PRoR)
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2
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Organization
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Developer
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Betan Karnali Sanchayakarta Hydropower Company Ltd.
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Consultant
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NEA Engineering Company Ltd.
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3
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Hydrology
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Catchment area
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22,511.25 km2
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Mean annual flow
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553.92 m3/s
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Maximum average monthly discharge
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1609.55 m3/s
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Minimum average monthly discharge
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134.80 m3/s
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1 in 100 years flood (Q100)
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8,530.00 m3/s
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1 in 1000 years flood (Q1000)
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11,548.00 m3/s
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1 in 10,000 years flood (Q10,000)
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14,560.00 m3/s
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Probable maximum flood (QPMF)
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22,604.00 m3/s
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4
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Reservoir
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Gross storage volume
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161.69 Mm3
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Live storage volume
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36.19 Mm3
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Surface area at FSL
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5.42 km2
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Length of reservoir at FSL
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21.93 km
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Full supply level
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473.30 masl
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Monsoon operating level
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470.00 masl
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Minimum drawdown level
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466.00 masl
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5
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River Diversion Works
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Diversion discharge
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2,400.00 m3/s
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Number of tunnels
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2 Nos.
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Size and shape
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9.80 m diameter horseshoe
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Length
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584.40 m & 727.10 m
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Inlet and outlet level
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400 masl & 394 masl (Diversion tunnel-1)
400.50 masl and 393.50 masl (Diversion tunnel-2)
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Lining
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Reinforced concrete lining
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U/S cofferdam
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Type & location (axis)
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RCC (Permanent), 162.00 m u/s from dam axis
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Height
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40.96 m from existing riverbed
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Crest Level
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434.32 masl
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D/S cofferdam
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Type & location (axis)
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Embankment dam, 306.00 m d/s from dam axis
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Height
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16.50 m from existing riverbed
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Crest level
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406.00 masl
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6
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Dam
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Type of dam
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Roller Compacted Concrete (RCC)
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Location of dam
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Approx. 2.00 km D/S from Malumela
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Dam crest length
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172.75 m
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Dam height
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90.00 m from riverbed
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Dam height
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140.00 m from foundation bed
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Top width
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10.00 m
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Dam top elevation
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480.00 masl
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7
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Spillway
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A
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Main Spillway
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Type
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Ogee and gated
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Crest elevation
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462.00 masl
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Number and size of gates
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6 nos, 11 m x 12 m (W X H)
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Energy dissipation
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Flip bucket
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B
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Sluice Spillway
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Type
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Sluice
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Crest elevation
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418.00 masl
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Number and Size
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6 nos, 7 m x 8 m (W X H)
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C
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Auxiliary Spillway
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Type
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Ogee and gated
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Crest elevation
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469.00 masl
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Number and Size
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1 no, 8 m x 5 m
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Energy dissipation
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Flip bucket
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8
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Intake
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A
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Main Power Intake
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Type of intake
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Side intake
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Number and size of trashrack
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9 nos., 5.90 m x 17.20 m (W X H))
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Number and size of intake gate
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3 nos., 8 m x 8 m (W X H)
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Dry season design discharge
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536.00 m3/s
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Wet Season design discharge
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551.33 m3/s
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Invert level
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450.00 masl
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Deck level
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480.00 masl
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Trashrack
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Inclined at 75⁰ to horizontal
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B
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Intake for Dam Toe Powerhouse
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Type of intake
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Embedded in dam
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Number and size of trashrack
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2 nos, 2.60 m wide up to dam deck level
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Number and size of intake gates
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2 nos, 1.6 m x 2 m
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Invert level
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460 masl
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Design discharge
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13.48 m3/s
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Trashrack
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Vertical
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9
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Headrace Tunnel
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Number
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3 nos.
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Size and Shape
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8.00 m diameter circular
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Length
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2017.26 m, 2011.15 m, 2017.39 m
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Lining
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450 to 300 mm thick concrete lining
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Design velocity
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3.56 m/s
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Maximum velocity
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3.66 m/s
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10
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Upstream Surge Shaft
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Type
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Restricted orifice
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Number
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3 nos
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Diameter
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24.00 m
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Diameter of orifice
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4.20 m
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Height
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37.70 m
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11
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Pressure Shaft and Pipes
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A
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Pressure shaft
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Number
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3 nos
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Orientation
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Vertical and horizontal
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Diameter and length (concrete lined)
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7.65 m circular pressure shaft of 109.80 m
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Diameter and length (Steel lined)
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7.65 m circular pressure shaft reducing to 7m before bifurcation of 42m
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B
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Bifurcated Pipes
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Diameter and length
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4.95 m circular bifurcating steel pipes of 79.36 and 72.74m of in each conveyance system
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12
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Penstock for Dam Toe Powerhouse
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Type
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Surface & steel
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Number
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2
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Diameter
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1.40 m
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Length
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100.87 m
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13
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Powerhouse
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A
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Main Powerhouse
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Coordinate
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81⁰14’48” E, 28⁰55’5” N
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Type
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Underground
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Installed capacity
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430.13 MW
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Powerhouse size
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202.00 x 23.50 x 54.48 (L X W X H)
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Number and capacity of units
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6 nos x 71.68 MW
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Type of turbine
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Francis, Vertical Axis
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Normal tail water level
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374.15 masl
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Gross head
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99.13 m
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Net head at FSL
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94.13 m
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Net head at MOL
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90.54 m
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Machine floor level
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380.21 masl
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Generator floor level
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375.61 masl
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Turbine floor level
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371.85 masl
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Turbine centre line level
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369.17 masl
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B
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Dam Toe Powerhouse
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Type
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Surface Toe of Dam
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Installed capacity
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8.77 MW
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PH size
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27.00 m X 15.60 m X 40.37 m (L X W X H)
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Number and capacity of units
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2 nos x 4.38 MW
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Type of turbine
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Francis, Vertical Axis
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Normal tail water level
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395 masl
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Gross head
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78.30 m
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Rated net head
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76.50 m
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14
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Tailrace Tunnel
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Number
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6 nos
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Size and shape
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6.5 m diameter concrete lined tunnel
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Length
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322.49 m, 312.26 m, 302.03 m, 291.80 m,
281.57 m and 271.35 m
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15
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Downstream Surge Shaft
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Type
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Restricted orifice
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Number
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1 (Chamber)
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Orientation
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Across and above 6 TRTs
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Size
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144 m x 15 m X 19.95 m (L X W X H)
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Diameter of orifice
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4.40 m
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16
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Tailrace Channel
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Size and Shape
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Trapezoidal Channel
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Length
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96.27 m at centreline
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Average width
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100 m
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17
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Energy
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Wet season energy
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1609.67 GWh/yr
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Dry season peak energy
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458.56 GWh/yr
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Dry season off peak energy
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230.82 GWh/yr
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Dry season total energy
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689.38 GWh/yr
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Total annual energy
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2299.05 GWh
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18
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Transmission Line
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Substation
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Bagmara Substation, Puchma
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Connection length
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5.00 km approx.
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Voltage
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400 kV
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