Liujiaxia Dam

Liujiaxia Dam. Located on the upper reaches of the Yellow River in Yongjing County, Gansu province, it is a major hydroelectric and water control structure. As one of the first large-scale dams built on the Yellow River in the modern era, it marked a significant milestone in China's water conservancy and power generation history. The dam forms a large reservoir that plays a crucial role in regulating flow for downstream regions, including the North China Plain.

History

The project was conceived during the early years of the People's Republic of China as part of a national strategy to harness the Yellow River. Planning intensified following the great floods of the 1950s, with formal approval granted under the First Five-Year Plan. Construction commenced in 1958, a period coinciding with the Great Leap Forward, which presented both mobilization challenges and material shortages. Despite these difficulties, including a temporary suspension, work continued with technical assistance from the Soviet Union. The dam was ultimately completed and began operations in 1974, becoming a symbol of industrial progress and a foundational project for subsequent developments like the Longyangxia Dam and the Xiaolangdi Dam.

Design and construction

The Liujiaxia Dam is a concrete gravity dam, a design chosen for its stability in the narrow gorge of the Yellow River. Its core structure relies on the sheer mass of concrete to resist the immense hydraulic pressure of the reservoir. Key construction challenges included dealing with complex geology and the harsh, arid climate of Gansu. Engineers employed innovative techniques for mass concrete pouring and temperature control to prevent cracking. The spillway section is designed for high flood discharge, while the intake structures feed water to the underground powerhouse. The project utilized significant domestic labor and machinery, becoming a training ground for China's nascent hydroelectric engineering sector.

Operations and purpose

The primary operational purposes are hydroelectricity generation, flood control, and providing water for irrigation. The dam's power station, with an installed capacity of 1,225 MW, supplies a substantial portion of the regional grid operated by the Northwest China Grid, aiding the industrial development of provinces like Gansu and Qinghai. For flood control, the reservoir retains peak flows during the summer monsoon season, protecting downstream cities and agricultural areas. It also stores water for irrigation, releasing it during dry periods to support agriculture in the Loess Plateau region. Additionally, the reservoir aids in sediment retention and ice flood mitigation on the Yellow River.

Environmental and social impact

The creation of the large reservoir led to the submersion of extensive areas of farmland and several villages, requiring the relocation of thousands of residents, primarily from Yongjing County. While the dam controls floods and provides irrigation, it has also altered the local ecosystem, affecting fish migration and downstream sediment flow, which can impact agricultural soil fertility. The reservoir itself has induced seismic activity, recorded as reservoir-induced seismicity. On a positive note, the project reduced reliance on coal-fired power plants in the region, contributing to lower regional air pollution. The reservoir has also spurred local tourism and fisheries, though these benefits are balanced against the displaced communities and ecological changes.

Technical specifications

The dam stands 147 meters tall and stretches 840 meters in length at its crest. The total reservoir capacity is approximately 5.7 cubic kilometers, with a surface area reaching 130 square kilometers at full pool. The underground powerhouse contains five main units, each driven by a Francis turbine with a capacity of 245 MW, for a total installed capacity of 1,225 MW. The average annual power generation is around 5.7 terawatt-hours. Other key features include a gated spillway with a maximum discharge capacity of over 7,500 cubic meters per second and bottom outlets for sediment flushing. The dam's structure contains over 4 million cubic meters of concrete and was built to withstand seismic activity.

Category:Dams in China Category:Hydroelectric power stations in Gansu Category:Buildings and structures in Gansu Category:Dams on the Yellow River