Overview

The Lianghekou Dam is a major hydroelectric infrastructure project located in Yajiang County, Sichuan Province, China. It is situated on the Yalong River, a significant tributary of the Yangtze River, specifically at the confluence of the Yalong, Xianshui, and Qingda Rivers. The structure is classified as a clay-core rockfill embankment dam and is currently operational. With a height of 295 metres, it holds the distinction of being the highest embankment dam in China. The facility supports a power station with an installed capacity of 3,000 MW, operated by Yalong Hydro.

Development of the Lianghekou Dam involved extensive preliminary studies conducted between 2005 and 2009. Following these studies, preliminary construction activities began in 2009. Major construction works officially commenced in October 2014. The power generation phase started in September 2021, when the first two generators were commissioned. The final unit was put into service in March 2022, completing the initial phase of operations.

The dam plays a critical role in the regional energy infrastructure by regulating river flow. The reservoir features a relatively large active capacity in relation to the Yalong River's annual flow. This characteristic allows for multi-year regulation of the river's discharge. By smoothing out flow peaks and troughs, the Lianghekou Dam enhances the output efficiency of downstream hydroelectric power stations along the Yalong River corridor. This regulatory function is essential for optimizing the overall hydroelectric potential of the basin.

Geography and Site Characteristics

The Lianghekou Dam is situated in Yajiang County, Sichuan Province, China, positioned strategically at the confluence of three major waterways: the Yalong River, the Xianshui River, and the Qingda River. This specific geographic location on the Yalong River, which serves as a significant tributary of the Yangtze River, defines the hydroelectric powerplant's operational context within the broader regional energy infrastructure. The site selection leverages the natural topography where these rivers meet, allowing for efficient water capture and management for power generation purposes.

Reservoir Characteristics and Flow Regulation

This specific hydrological characteristic enables the dam to regulate river flow across multiple years, providing a level of temporal storage that is critical for consistent power output. By smoothing out the natural peaks and troughs in river flow, the Lianghekou Dam plays a vital role in enhancing the efficiency of downstream hydroelectric power stations. This multi-year regulation capability ensures a more stable water supply for subsequent turbines, thereby increasing their overall output and optimizing the performance of the entire Yalong River hydroelectric cascade.

Construction History and Timeline

Development of the Lianghekou Dam project commenced with an initial phase of engineering studies conducted between 2005 and 2009. Following the completion of these preliminary investigations, early construction activities began in 2009 to prepare the site for major structural works. The official commencement of major construction works on the dam structure took place in October 2014, marking the transition from preliminary site preparation to the primary building phase of the clay-core rockfill embankment.

The construction timeline culminated in a phased commissioning process that spanned two calendar years. The first two generators were officially commissioned in September 2021, initiating the operational phase of the 3,000 MW power station. The final unit was put into service in March 2022, completing the installation of all generating capacity for the facility.

Year Event
2005–2009 Completion of engineering studies for the Lianghekou Dam project.
2009 Beginning of preliminary construction activities.
October 2014 Official start of major works on the dam structure.
September 2021 Commissioning of the first two generators.
March 2022 Commissioning of the final unit, completing the 3,000 MW capacity.

Technical Specifications and Engineering

The Lianghekou Dam is engineered as a clay-core rockfill embankment structure, representing a significant advancement in high-altitude hydroelectric infrastructure in China. This structural form utilizes a central clay core surrounded by rockfill material, a design choice that provides flexibility and stability essential for the geological conditions of the Yalong River basin. The dam is situated at the strategic confluence of the Yalong, Xianshui, and Qingda Rivers, a location that maximizes the hydraulic head and storage potential for the associated power station.

Power Station Capacity and Configuration

This capacity places the Lianghekou project among the largest hydroelectric facilities in the region, contributing substantially to the energy output of the Yalong River cascade. The power station was brought online in stages, with the first two generators commissioned in September 2021 and the final unit entering service in March 2022. The operational status of the plant is currently active, delivering consistent power generation to the regional grid.

Reservoir Regulation and Engineering Significance

A key engineering feature of the Lianghekou Dam is its reservoir's relatively large active capacity relative to the river's annual flow. This characteristic enables multi-year regulation of the river flow, allowing operators to smooth out peaks and troughs in water volume. This regulation is critical for optimizing the output of downstream hydroelectric power stations, enhancing the efficiency of the entire Yalong River cascade. The ability to store water over multiple years provides a buffer against seasonal variations and improves the overall reliability of the hydroelectric system. The construction of such a high embankment dam in this terrain required extensive studies completed between 2005 and 2009, with preliminary construction beginning in 2009 and major works officially commencing in October 2014. The successful completion and operation of the Lianghekou Dam demonstrate advanced engineering capabilities in managing large-scale water resources in complex topographical settings.

Why it matters

The Lianghekou Dam holds a distinct position in China’s hydroelectric infrastructure as the highest embankment dam in the country, standing 295 metres tall. This structural achievement is significant because it utilizes a clay-core rockfill design rather than the concrete gravity or arch structures often associated with high-elevation dams in the region. Its location at this specific hydrological junction allows for effective water capture and management within the broader Yalong River basin.

Hydrological Regulation and Downstream Impact

Beyond its structural height, the Lianghekou Dam plays a critical functional role in the regional energy grid through multi-year flow regulation. The reservoir possesses a relatively large active capacity in relation to the river's annual flow, which enables it to store water over extended periods. This capacity allows the dam to smooth out the natural peaks and troughs of the river flow. By regulating the discharge, the dam increases the output efficiency of downstream hydroelectric power stations. This cascading effect is vital for the Yalong River basin, which hosts a series of hydropower plants that benefit from the stabilized water volume provided by Lianghekou.

Comparative Context

The 3,000 MW power station supported by the dam represents a substantial addition to China’s installed hydroelectric capacity. The project’s development timeline reflects the scale of the engineering effort, with studies completed between 2005 and 2009 and preliminary construction beginning in 2009. The dam is operated by Yalong Hydro, a key player in the region’s energy production. As the highest embankment dam in China, Lianghekou demonstrates the continued evolution of rockfill technology in large-scale hydropower projects, combining significant height with effective reservoir management to optimize downstream energy generation.

How does the dam regulate downstream hydroelectric output?

The Lianghekou Dam plays a critical role in the hydroelectric cascade of the Yalong River by providing multi-year flow regulation capabilities. This regulatory function is made possible by the reservoir's relatively large active capacity when compared to the river's annual flow volume. By storing water during periods of high inflow and releasing it strategically during drier periods, the dam smooths out the natural peaks and troughs of the river's discharge. This stabilization of flow is essential for optimizing the performance of downstream hydroelectric power stations, which often rely on a more consistent water supply to maximize their energy output.

Reservoir Capacity and Flow Management

The design of the Lianghekou Dam, a 295-metre-tall clay-core rockfill embankment structure, creates a reservoir with significant storage potential. The relationship between the reservoir's active capacity and the annual flow of the Yalong River allows for regulation that extends beyond a single hydrological year. This means that water can be stored during wet years or seasons and utilized in subsequent years, effectively balancing inter-annual variations in precipitation and runoff. Such long-term regulation is particularly valuable in mountainous regions like Yajiang County in Sichuan Province, where seasonal snowmelt and monsoon rains can create dramatic fluctuations in river levels.

Impact on Downstream Power Stations

The smoothing of river flow peaks and troughs directly benefits the downstream hydroelectric power stations along the Yalong River, a major tributary of the Yangtze River. Without this regulation, downstream plants might experience periods of underutilization during low-flow seasons or potential overflow and turbine stress during peak flow events. The Lianghekou Dam helps to mitigate these extremes, ensuring a more stable and predictable water supply for the turbines of subsequent plants. This coordinated operation enhances the overall efficiency and energy yield of the entire hydroelectric cascade, contributing to the stability of the regional power grid. The 3,000 MW power station at Lianghekou itself is a significant contributor to this system, but its regulatory role amplifies the output of the broader network.

See also