Three Gorges Dam

Key characteristics

The structure itself spans more than two kilometers and rises to nearly two hundred metres in height. Its installed electrical capacity is commonly reported at about 22,500 megawatts, making it larger than many other major hydroelectric plants such as the Itaipu Dam in Brazil and Paraguay. The dam created a reservoir that extends hundreds of miles upstream; this reservoir is often cited as stretching roughly 410 miles (410 mi, about 660 km) toward the municipality of Chongqing.

Purposes and components

The project combines several functions:

• Hydropower: Large turbines convert river flow into electricity that feeds the national grid.
• Flood control: The reservoir can store seasonal floodwaters, lowering peak flows downstream; flood-related aims were a driving rationale for construction (flood control).
• Irrigation and water management: Regulated flows can support agriculture and municipal water supply (irrigation).
• Navigation: Ship locks and a ship lift permit larger vessels to travel farther inland, reducing transport costs and improving access to upstream ports.

History and construction

The dam was the culmination of planning and debate over several decades. Major construction and river impoundment took place in the late 20th and early 21st centuries; the final generating units were brought online in the early 2010s and the project was declared complete in 2012. The work involved large civil-engineering efforts: diversion of the river during construction, installation of heavy equipment and creation of a long reservoir.

Impacts and controversies

While the facility produces large amounts of low-carbon electricity and provides downstream flood protection, it has also produced significant social and environmental effects. The reservoir submerged archaeological sites, cultural landscapes and many towns; estimates of people relocated are commonly given at around 1.2 million. Ecological concerns include altered river ecology, changes to sediment transport, increased landslide risk on some slopes above the reservoir and impacts on fisheries. Resettlement, heritage loss and long-term environmental management have remained sources of public debate.

Importance and notable facts

The Three Gorges Dam is a prominent symbol of modern engineering in China and plays a major role in the country's electricity system and river management strategy. It demonstrates trade-offs typical of large infrastructure: substantial renewable-energy generation and navigation benefits on one hand, and major social, cultural and environmental costs on the other. For more technical and historical resources consult published works and official project summaries, or follow these topical links for further reading:

• Chinese name and official descriptions
• Structural and engineering details
• Yangtze River context
• National policies and regional planning in China
• Comparisons with other dams (Itaipu)
• Itaipu and international hydroelectric projects
• Flood control analyses
• Irrigation and water-use studies
• Reservoir extent in miles
• Reservoir extent in kilometres
• Upstream reach and relationship to Chongqing

The Three Gorges Dam continues to be studied as a case of large-scale river engineering: its long-term legacy will be judged by how well economic, environmental and social challenges are managed as conditions evolve.