Xiangjiaba Dam: Powering China's Southern Grid

The **Xiangjiaba Dam** is a concrete gravity dam on the Jinsha River at the border of Yunnan and Sichuan provinces, approximately 1,500 kilometers upstream from the Three Gorges Dam. With an installed capacity of **6,448 MW**, it is one of the largest hydroelectric power stations in the world and forms the lowest step in the four-dam Jinsha River cascade.

Introduction

Completed in 2014, Xiangjiaba serves multiple purposes beyond power generation, including flood control for the middle and lower Yangtze, sediment management for the Three Gorges Reservoir, and navigation improvement on the Jinsha River. Its electricity is transmitted to Shanghai via one of the world's first ultra-high-voltage direct current transmission lines.

Engineering & Structure

• Type: Concrete gravity dam
• Height: 162 meters
• Crest Length: 909 meters
• Turbines: 8 × 800 MW + 2 auxiliary

Xiangjiaba is a concrete gravity dam with a maximum height of 162 meters and a crest length of 909 meters. While shorter than its upstream neighbor Xiluodu, Xiangjiaba is wider and built on a broader section of the Jinsha gorge. Its eight main turbine-generator units, each rated at 800 MW, were the world's largest single hydroelectric turbines when installed.

The dam's flood discharge system can handle up to 39,410 cubic meters per second, essential for controlling the Jinsha's powerful monsoon floods. The spillway employs energy dissipation basins at the toe of the dam to prevent erosion of the downstream riverbed. A navigation lock allows ships to bypass the dam, improving commercial shipping on the upper Yangtze.

Geographic Setting

• River: Jinsha River (upper Yangtze)
• Location: Shuifu, Yunnan / Yibin, Sichuan border
• Coordinates: 28.63°N, 104.40°E
• Reservoir Capacity: 5.16 km³

Xiangjiaba Dam sits where the Jinsha River transitions from its narrow mountain gorges into the broader Sichuan Basin, near the city of Yibin — historically known as the point where the Yangtze begins. The surrounding terrain shifts from the steep canyon walls of the upper Jinsha to the rolling hills of the basin's western edge.

The reservoir extends approximately 156 kilometers upstream through a mix of gorge sections and wider valley reaches. The area has a subtropical monsoon climate with hot, humid summers and mild winters. Yibin, just downstream, is a major transportation hub where the Min River joins the Jinsha to form the Yangtze proper.

Hydroelectric Power

• Installed Capacity: 6,448 MW
• Annual Output: ~30.7 TWh
• UHVDC Transmission: 800 kV line to Shanghai, 1,907 km

Xiangjiaba's eight 800 MW turbines were groundbreaking in size; each unit's runner weighs over 400 tonnes and spans 8.6 meters in diameter. Annual generation averages approximately 30.7 terawatt-hours, making it a major contributor to China's renewable energy portfolio.

The dam's electricity is transmitted to Shanghai via the Xiangjiaba-Shanghai UHVDC line, operating at ±800 kV and spanning 1,907 kilometers — one of the first commercial ultra-high-voltage direct current transmission links in the world. This technology minimizes power losses over long distances, delivering Xiangjiaba's clean energy to one of China's most power-hungry regions.

Environmental & Social Impact

• People Relocated: ~100,000
• Fish Conservation: Rare Yangtze fish species affected
• Sediment Management: Reduces sedimentation in Three Gorges Reservoir

The Xiangjiaba reservoir displaced approximately 100,000 people, primarily from rural communities along the Jinsha River valley in Yunnan and Sichuan. The resettlement involved constructing new towns, roads, and farmland, though the loss of fertile bottomland along the river was a significant hardship for many affected families.

The dam disrupts the habitat of several rare Yangtze basin fish species, including the Yangtze sturgeon. To mitigate this, fish passage facilities and artificial spawning programs were established, though conservation biologists question whether these measures can sustain wild populations long-term. On the positive side, the dam traps sediment that would otherwise accumulate in the Three Gorges Reservoir, extending that downstream facility's operational lifespan.

Key Facts

• Xiangjiaba Dam generates 6,448 MW from eight 800 MW turbines — the world's largest when installed.
• It forms the lowest step of the four-dam Jinsha River cascade.
• The 800 kV UHVDC line to Shanghai was a pioneering long-distance power transmission project.
• Approximately 100,000 people were relocated during construction.
• Annual output averages 30.7 TWh, transmitted to eastern China.

Fun Facts

• Each of Xiangjiaba's turbine runners weighs over 400 tonnes and took weeks to transport by road and river to the remote dam site.
• Yibin, just downstream, is known as the "First City of the Yangtze" because it marks the traditional starting point of the river.
• The dam's reservoir reduced the sediment reaching the Three Gorges Reservoir by approximately 10 percent, helping maintain storage capacity downstream.

Final Thoughts

Xiangjiaba Dam is a critical piece of China's Jinsha River cascade and a pioneering project in ultra-high-voltage power transmission. Its massive turbines and long-distance UHVDC connection to Shanghai demonstrate how remote hydroelectric resources can power distant urban centers efficiently.