Salient Technical Features

Official technical parameters and hydraulic specifications for the Tila-1 Hydropower Project based on the Detailed Project Report (DPR) formulated by Shah Consult International (P.) Ltd. and approved by the Department of Electricity Development (DoED), Ministry of Energy, Water Resources and Irrigation, Government of Nepal.
Project Name Tila-1 Hydropower Project (T1HPP)
Project Developer S.C. Power Company Pvt. Ltd. (SCPCPL)
Scheme Type Peaking Run-of-River (PRoR) with 6-Hour Daily Peaking Storage
Licensed Capacity 440 MW (PPA Capacity: 298.75 MW)
Province & District Karnali Province, Kalikot District, Nepal
Source River Tila River (Major perennial tributary of Karnali River Basin)
Dam Site Coordinates Latitude: 29°06’ 00” N | Longitude: 81°44’ 38” E (Downstream of Tila–Ruru Confluence)
Powerhouse Site Coordinates Latitude: 29°10’ 00” N | Longitude: 81°52’ 00” E (Underground, upstream of Serighat Village)
Gross Head 510.00 meters
Rated Net Head 468.00 meters
Design Discharge 101.00 m³/s (4 Pelton units)
Total Catchment Area at Intake 3,355 km²
Rain-fed Catchment Area 3,080 km²
Snow-fed Catchment Area 275 km² (Assuming permanent snowline at EL. 4,500 masl)
Annual Average Precipitation 1,082 mm
Annual Average Runoff Yield 803 mm
Probable Maximum Flood (PMF) 13,821 m³/s (cumecs)
Diversion Flood Discharge (1-in-10-Year) 660 m³/s (cumecs)
Full Reservoir Level (FRL) 1,295.00 masl
Minimum Draw Down Level (MDDL) 1,275.00 masl
Gross Storage Volume 2.30 Million Cubic Meters (MCM)
Live Peaking Storage Volume 1.70 Million Cubic Meters (MCM)
Reservoir Surface Area at FRL 11.60 hectares
Reservoir Backwater Length 895 meters
Dam Structure Type Concrete Gravity Dam
Dam Crest Elevation (Top Level) 1,298.00 masl
River Bed Elevation 1,243.00 masl
Dam Height above River Bed 55.00 meters
Dam Crest Length 182.40 meters
Spillway Configuration Gated Ogee Type with Breast Wall
Number of Spillway Bays & Gates 7 Radial Crest Gates
Gate Dimensions 7.70 m (width) × 13.50 m (height) each
Spillway Crest Elevation 1,255.00 masl
Energy Dissipator Trajectory Type Ski-jump Bucket (Invert: 1,243.0 m, Lip: 1,247.69 m)
Diversion Tunnel Dimensions 462 m length, 7.60 m diameter, Modified D-shape, pressure flow
Diversion Tunnel Capacity 660 m³/s (1-in-10-year flood capacity)
Power Intake Design Discharge 122.12 m³/s (includes 20% sediment continuous flushing discharge)
Number of Intake Bays 2 Openings with inclined trash racks (10° from vertical)
Intake Sill Invert Level 1,265.50 masl
Feeder Tunnels 2 D-shaped tunnels, 4.40 m diameter (Tunnel 1: 195.5 m | Tunnel 2: 153.5 m)
Desilting Basin Type 2 Dufour-type underground sediment settling chambers
Desilting Basin Dimensions 12.0 m (width) × 18.8 m (height) × 290.0 m (length) each
Sediment Exclusion Threshold All particles coarser than 0.20 mm diameter
Silt Flushing Tunnels 2 Modified D-shaped free-flow tunnels (1.5 m × 2.7 m; 42 m & 77 m length)
Headrace Tunnel (HRT) Length 13,770 meters (13.77 km)
Tunnel Cross-Section & Lining Modified Horseshoe shape, 6.00 m internal diameter, concrete lined
Design Waterway Discharge 101.76 m³/s
Construction Access Adits 6 Adits (5.0 m × 6.0 m modified D-shaped)
Surge Shaft Type Open to sky, restricted orifice circular surge tank
Surge Shaft Dimensions 10.00 m internal diameter, 128.00 meters vertical height
Surge Levels Top: 1,350.0 masl | Max Upsurge: 1,348.0 masl | Min Downsurge: 1,227.5 masl
Main High-Pressure Shafts 2 Steel-lined circular shafts, 3.25 m diameter (Shaft 1: 846 m | Shaft 2: 816 m)
Branch Penstocks 4 Steel penstocks, 2.50 m diameter (Lengths: 43 m, 38 m, 56 m, 50 m)
Powerhouse Cavern Type Underground rock cavern complex
Machine Hall Cavern Sizing 18.50 m (width) × 69.50 m (length)
Transformer Cavern Sizing 16.00 m (width) × 121.90 m (length)
Turbine Type Vertical-axis Pelton Wheel Turbines
Number of Turbine Units 4 Units
Rated Capacity per Unit 110 MW per turbine (440 MW total mechanical output)
Turbine Efficiency 92.0%
Governor System High-precision electronic governor with PID digital control
Generators 4 Units, Synchronous, 3-phase, salient pole, brushless excitation
Generator Rating 88.23 MVA per unit, 11 kV generation voltage, 50 Hz, 0.85 power factor
Generator Efficiency 97.0%
Step-Up Transformers 13 Single-Phase units (including 1 spare), 29.5 MVA each, 11 kV / 400 kV, ONAN, 99% efficiency
Tailrace Tunnel 642 meters length (Free-flow discharge back to Tila River)
Grid Transmission Line 400 kV Double Circuit, 6 km length connecting to RPGCL Phukot Hub Substation