Xiaowan Hydropower Station

The Xiaowan Hydropower Station is a landmark project of the national Western Development Initiative. Located on the middle reaches of the Lancang River in Yunnan Province, it serves as the key reservoir and power station in the river’s cascade development. While primarily designed for power generation, it also provides flood control, irrigation, sediment retention, and navigation. The project features a concrete double-curved arch dam, a spillway tunnel, and an underground powerhouse. At 294.5 m high with a crest arc length of 892.8 m, it was the world’s tallest and most heavily loaded arch dam at the time. Its reservoir holds 15 billion m³ and provides multi-year regulation for the middle and lower Lancang River. The power station has an installed capacity of 4,200 MW, generating an average of 19 billion kWh annually.

Figure 1. Aerial view of the Xiaowan Dam (Source: Xinhua News Agency)

During construction, several world-class technical challenges were overcome, leading to key innovations:

(1) Structural Design for Ultra-High Arch Dams: A new theoretical framework, optimized concrete mix, and flexible seepage control enabled the dam height to increase from 272 m to 294.5 m.

(2) High Seismic Safety: For accelerations up to 0.313 g, novel seismic design methods, transverse joint reinforcement, and crest vibration-damping devices were developed, which have been incorporated into national design standards.

(3) Slope Stabilization: Techniques were created for extremely steep slopes over 700 m, including specialized anchoring rigs, load-distributing anchors, and 3D slope stability analysis.

(4) Temperature Control and Safety Monitoring: Advanced cooling strategies and temperature standards minimized cracking, complemented by a 3D visualization system for real-time safety monitoring.

The construction of the Xiaowan Hydropower Station overcame a series of technical challenges in both design and construction, set multiple world records, and raised China’s capabilities in high-arch dam construction to new heights.