Tanahu Hydropower Project, Nepal

Seti River Gorge at Main Dam Axis

Located on the Seti River in the Middle of Nepal, in the Tanahu district near the town of Damaule, the Tanahu Hydropower Project represents the second and currently largest storage reservoir project in Nepal in comparison to the previous run-of-river hydropower projects. It is part of the ambitious ADB programme to mediate the energy shortage in Nepal, which was established in 1999. The feasibility and basic design was finished in 2014.

Tanahu Hydropower Limited was established by the Nepal Electricity Authority specifically for the project.

Within the scope of the consultant’s services, the review of the basic design documents and the review of the prepared contract documents for three contract packages for head-works, power tunnel and powerhouse cavern, and the power transmission line with substation connection to the national electricity grid was finished in 2015. The originally envisaged roller compacted concrete (RCC) dam was reconsidered in favour of the option of a conventional concrete dam.

For the dam, tunnels and the powerhouse cavern a local seismic hazard study is required and contracted to Lahmeyer as an earthquake peak ground acceleration (PGA) > 0.55g is expected.

The dam in a narrow and steep valley with very limited access requires additional investigation related to karstification, and the related karst grouting measures in subbase and abutments.

The Tanahu Hydro Power Project was designed for a one year storage volume reservoir allowing 11 months of power generation between the sediment flushing time of an estimated one month per year.

The installed capacity will be 144 MW generated by two Francis turbines. 

ClientTanahu Hydropower Limited, Thapathali Trade Tower, Kathmandu
LocationNepal
Executionsince 2015
Technical Data
Dam
  • Type
concrete gravity
  • Height / Length
140.0 m / 175.0 m
  • Volume
800,000 m³
  • Reservoir Effective Volume
100 million m³
  • Gross head
115.80 m
  • Two diversion tunnels, diameter
11.0 m
Powerhouse
  • Cavern (width/height/length)
27 m / 46 m / 100 m
  • Rated discharge
127.4 m³/s
  • Installed capacity
2 x 71.8 MW
  • Rated capacity
127 MW
  • Annual energy output
480 GWh
Headrace tunnel
  • Length
about 1350 m
  • Diameter
7.40 m
Services
  • Review of basic design, and contractor’s detailed designs
  • Review of construction and supply contracts
  • Review of financing arrangements
  • Assistance in contract negotiations
  • Assistance in project accounting
  • Construction supervision and Quality Assurance
  • Contract management of three contractors
  • Training of Client’s personnel, and support of operation in first 5 years operation phase

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