On November 29, in the Sichuan-Tibet section of the upper reaches of the Jinsha River at the junction of Sichuan province and the Tibet autonomous region, with the last truckful of rocks falling into the closure gap, the Rawa River Hydropower Station, a world-class project surveyed, designed, and constructed by POWERCHINA, was successfully completed, marking an important milestone in the building of world-class concrete-faced rockfill dams.
The closure was also a major step forward in the construction of a clean energy base on the upper reaches of the Jinsha River, one of China's nine major clean energy bases to be built during the country's 14th Five-Year Plan (2021-2025).
The Rawa Hydropower Station is located on the main stream of the Jinsha River at the junction of Garze Prefecture in Sichuan province and Qamdo in the Tibet autonomous region. It is the eighth-level hydropower station in the 13-level hydropower station development plan for the upper reaches of the Jinsha River.
The concrete-faced rockfill dam is the second highest in the world with a crest height of 2,709 meters and a maximum dam height of 239 meters.
The Rawa Hydropower Station has a total installed capacity of 2 million kilowatts, with an average annual power generation capacity of 8.37 billion kWh. Its main structure consists of the concrete faced rockfill dam, an underground water transmission system on the right bank, two spillways and one flood discharge tunnel.
In the construction process, engineers tackled a number of technical challenges such as building a 250-meter high faced rockfill dam in a highly seismic area, creating flood-release installations for mass and high velocity flow, building 500-meter high and steep slopes, placing high cofferdams over weak 70m-deep lacustrine sediments, and accommodating a group of dense underground caverns.
The POWERCHINA Zhongnan Survey, Design, and Research Institute surveyed and designed the hydropower station throughout the whole process, while PowerChina subsidiaries undertook its main construction.
Since the start of survey and design in 2006 and approval of the project's feasibility study and review in the end of 2017, the river closure lasted for 16 years and the first unit of the hydropower station is scheduled to be put into operation by the end of June 2027.
The Jinsha River section of the upper reaches of the Yangtze River where the power station is located features a large natural river gradient, a narrow riverbed, turbulent water flow, and strong water erosion.
As the maximum flow rate of the river closure gap is 11.3 m/s and the water drop is about 9.4 m, nearly 200,000 cubic meters of stone was required for river closure.
In addition, due to the extreme cold weather and high altitude in the plateau, labor and mechanical efficiency was significantly lowered, making the river closure one of the most difficult river closure projects in China.
To ensure a successful river closure, POWERCHINA's Sinohydro Bureau 12 Co., Ltd made emergency plans, and took construction quality assurance measures and safety technical measures into full consideration.
An on-site monitoring station was set up to measure and analyze hydrological indicators such as the water flow, water level, water flow rate and water surface width, so as to ascertain the water situation in the closure gap area and provide a basis for stone dumping.
The river closure process took about 12.5 hours with reinforced stone cages, large stones, alloy mesh pockets, and concrete tetrahedrons being continuously thrown into the river, setting a new record in river closure times for large-scale hydropower projects in China.
In addition, the fourth bureau and the first bureau companies carried out scientific and technological research when constructing the diversion project for river closure, and built the longest and largest diversion tunnel project in the country.
Completion ceremony of the project.
The Rawa Hydropower Station is one of the major projects supported by the Chinese central government for Tibet's economic and social development, and is a major project for the construction of the national "West-to-East Power Transmission" base and the southwest hydropower base.
As a key hydropower project in the impoverished area, it will also help alleviate poverty during the 13th Five-Year Plan period, and be an important part of the construction of a 30-million-kilowatt state-level large-scale wind, photovoltaic and water storage demonstration base in the Sichuan-Tibet section of the upper Jinsha River.
The hydropower station is expected to save 2.45 million tons of standard coal and reduce CO2 emissions by 5.14 million tons each year. In that way it will help China achieve its "double carbon" goal and continue the "West-to-East Electricity Transmission" strategy.
