Thac Ba Hydropower Project

Project location: Chay river, Yen Bai province

Project tasks:

- Power generation

- Flood control

Construction time:

- Commencement date: 19/08/1964

- River closure date: 22/02/1970

- Operation date of unit No.1: 05/10/1971

- Grid connection date: 19/05/1972

- Completion time: 12/1972

Two problems occurred during construction and after completion of the project are as follows:

- Migration of great number of people

- Rapid sedimentation speed in reservoir bed resulting to reduction of reservoir life

Consultants: Bacu Hydro-energy Design Institute (former Russia)

Corporation agency: Vietnam Hydropower, Hydraulic Design Institute (now HEC)

Major technical parameters

- Project grade: II

- Catchment area: 6 140 km²

- Normal water level: +58.00

- Dead water level: +46.00

- Parapet crest elevation: +63.00

- Check frequency P%=0.01% at elevation: +62.00

^- Total storage capacity: 2160 million m³

^- Dead storage capacity: 780 million m³

Scale and structure of project works

- Main dam: Rockfill dam, Hmax: 36m

- Auxiliary dam: 16 dams (12 on right bank, 04 on left bank)

- Spillway located on left bank, spillway width B: 68m, Q: 3 280 m³/s, gated spillway

- Lock

- Turnout: on left abutment of auxiliary dam No.3, dimension: 2x2m, length: 91m, design discharge Q: 10 m³/s.

- Riverbed type hydropower plant with closed roof, 3 units, capacity of each unit: N=36MW. Turbine Õp-5a. Bb-450. Total capacity N=108MW. Annual average power output E: 411 million KWh. Annual capacity used hours: 3800h.