Jiemian Dam: Hydroelectric Infrastructure on the Junxi River

Overview

The Jiemian Dam is a major hydroelectric infrastructure project located in Youxi County, within Fujian Province, China. It is situated on the Junxi River and functions primarily as a water-retention structure designed to harness hydraulic energy for electricity generation. The facility is classified as a concrete-face rock-fill dam, a specific engineering design that combines the flexibility of a rock-fill core with a rigid concrete slab facing to withstand water pressure. This structural type is particularly suited for the topographical and geological conditions found in the Fujian region, allowing for efficient construction and long-term operational stability.

The dam supports a dedicated power station with an installed capacity of 300 MW. This output is generated through two primary generator units. The construction of the Jiemian Dam commenced in 2002, marking the beginning of a multi-year development phase. The reservoir was officially impounded on 17 February 2007, initiating the storage of water necessary to drive the turbines. The first generator, with a capacity of 150 MW, was commissioned on 28 November 2007, bringing the plant to partial operational status. The second 150 MW generator followed, being commissioned in 2008, thereby completing the full 300 MW capacity of the facility. The Jiemian Dam remains operational, contributing to the regional power grid in China.

What is the structural design of Jiemian Dam?

The Jiemian Dam employs a concrete-face rock-fill (CFR) structural design, a technology chosen for its efficiency in hydroelectric projects where rock availability is high. This dam type consists of a core of compacted rock fill, faced with a thin layer of concrete slabs that act as the primary water barrier. The Junxi River in Youxi County, Fujian Province, provided the geographical and geological context for this application, allowing the structure to support a 300 MW power station. The concrete face provides a smooth, impermeable surface that resists seepage and abrasion from the river flow, while the rock-fill core offers stability and flexibility to accommodate settlement and thermal expansion. This design is particularly effective for medium-height dams, balancing construction speed and material costs.

Technical Specifications

The construction of the Jiemian Dam began in 2002, with the reservoir being impounded by 17 February 2007. The first 150 MW generator was commissioned on 28 November 2007, and the second unit followed in 2008, completing the 300 MW capacity. The CFR design allowed for a relatively rapid construction timeline, leveraging local rock resources to form the dam body. The concrete face is critical for maintaining water tightness, especially in the variable flow conditions of the Junxi River. This structural approach minimizes the amount of concrete required compared to a solid gravity dam, reducing material costs and construction time. The dam's operational status remains active, contributing to the regional energy mix in Fujian Province. The design's resilience and efficiency have made it a viable option for similar hydroelectric projects in mountainous regions with abundant rock fill material. The successful commissioning of both units within a short timeframe highlights the effectiveness of the CFR technology in this specific geographical context.

Construction and Commissioning History

Construction of the Jiemian Dam, a concrete-face rock-fill structure located on the Junxi River in Youxi County, Fujian Province, China, commenced in 2002. The project was designed primarily for hydroelectric power generation, supporting a power station with an installed capacity of 300 MW. The construction phase spanned approximately five years, culminating in the initial filling of the reservoir. By 17 February 2007, the reservoir was officially impounded, marking a critical milestone in the operational readiness of the facility. This date established the baseline for the subsequent commissioning of the generating units, transitioning the project from civil engineering works to mechanical and electrical integration.

Generator Commissioning Sequence

The commissioning of the hydroelectric generators followed a phased approach beginning late in the year of the reservoir's impoundment. On 28 November 2007, the first generator unit was commissioned into service. This initial unit contributed 150 MW to the total installed capacity, effectively bringing half of the power station online within less than a year after the reservoir was filled. The successful operation of this first unit validated the performance of the concrete-face rock-fill dam structure under initial hydraulic loads and confirmed the efficiency of the turbine-generator sets.

The second generator unit, also rated at 150 MW, was commissioned in 2008. The completion of this second unit finalized the power station's total capacity of 300 MW, allowing the Jiemian Dam to operate at full design output. The sequential commissioning strategy, with the first unit entering service in late 2007 and the second following in 2008, allowed for a staggered integration of power output onto the regional grid. This timeline reflects a relatively rapid construction and commissioning schedule for a rock-fill dam project, with the facility achieving full operational status within six years of the start of construction in 2002. The operator of the facility is not explicitly specified in the primary cited sources, though the operational status remains active.

Power Generation Capacity and Operations

The Jiemian Dam serves as the primary infrastructure for hydroelectric power generation on the Junxi River in Youxi County, Fujian Province. The facility is classified as a concrete-face rock-fill dam, a structural design that utilizes a rock-fill core faced with a concrete slab to retain the reservoir water. This engineering approach is common for medium-head hydroelectric projects in mountainous terrain, providing flexibility and cost-efficiency compared to traditional concrete gravity or arch dams.

Installed Capacity and Generator Configuration

This capacity is delivered through two distinct generator units. This initial commissioning followed the impoundment of the reservoir, which was completed on 17 February 2007. The second generator, also rated at 150 MW, was commissioned in 2008, thereby bringing the plant to its full 300 MW operational capacity.

The operational status of the Jiemian Dam is currently active. The phased commissioning of the generators allowed for a gradual integration of power output into the regional grid. The first unit began contributing to the energy mix in late 2007, less than a year after the reservoir was fully impounded. The completion of the second unit in 2008 marked the full realization of the project's 300 MW design capacity. The dam's primary purpose remains hydroelectric power generation, supporting the energy demands of the Fujian Province region. The concrete-face rock-fill construction method provides the necessary structural integrity to manage the water head required for the two 150 MW turbine-generator sets. No specific operator name is cited in the primary sources, though the facility functions as a key component of the local hydroelectric infrastructure.

Why it matters

The Jiemian Dam serves as a critical infrastructure node within the energy landscape of Fujian Province, China, contributing to the regional power supply through its 300 MW hydroelectric capacity. As a concrete-face rock-fill dam located on the Junxi River in Youxi County, it represents a specific technological approach to harnessing water resources in the province's varied topography. The facility’s operational status, having been commissioned in 2007, places it among the established assets in Fujian’s energy mix, providing a reliable source of renewable electricity that complements other generation methods in the region.

Role in the Junxi River Basin

Within the Junxi River basin, the Jiemian Dam functions as a primary mechanism for hydroelectric power generation. The construction of the dam, which began in 2002, transformed the river's flow dynamics to support energy production. By 17 February 2007, the reservoir was impounded, marking a significant milestone in the basin's infrastructure development. This impoundment not only facilitated the operation of the power station but also influenced the local hydrological environment, creating a storage capacity that allows for more consistent power output compared to run-of-the-river schemes.

The dam's design as a concrete-face rock-fill structure is particularly suited to the geological conditions of Youxi County. This technology involves a core of rock-fill material faced with a concrete slab, offering a balance between flexibility and impermeability. Such engineering choices are vital for maintaining the structural integrity of the dam while efficiently capturing the potential energy of the Junxi River. The successful implementation of this design underscores the technical capabilities applied to regional water management and energy extraction in Fujian.

Operational Milestones and Capacity

The commissioning of the Jiemian Dam's power station occurred in stages, reflecting a phased approach to integrating new capacity into the grid. On 28 November 2007, the first 150 MW generator was commissioned, immediately contributing half of the plant's total rated capacity to the regional network. The second 150 MW generator followed in 2008, bringing the facility to its full 300 MW potential. This staged commissioning allowed for operational testing and gradual load integration, minimizing disruption to the existing power supply in Fujian Province.

With a total capacity of 300 MW, the Jiemian Dam provides a substantial amount of electricity to the province. Hydroelectric power is a key component of Fujian's energy strategy, offering a renewable alternative to thermal and nuclear generation. The dam's location in Youxi County also highlights the distribution of energy infrastructure across the province, extending beyond coastal urban centers into inland river basins. This geographic spread helps to balance the load on the transmission grid and enhances the resilience of the regional energy system.

The operational history of the Jiemian Dam, from its construction start in 2002 to the full commissioning in 2008, demonstrates the timeline typical for mid-sized hydroelectric projects in China. The rapid development and commissioning phases reflect the broader acceleration of infrastructure investment in the early 21st century. As an operational asset, the dam continues to play a role in the Junxi River basin, contributing to both energy security and water resource management in Fujian Province.

Geographic and Environmental Context

The structure is situated on the Junxi River, a watercourse that serves as the primary hydraulic source for the facility. The dam is classified as a concrete-face rock-fill dam, a specific engineering design choice that influences its interaction with the surrounding landscape and river dynamics.

Construction activities on the site commenced in 2002. The reservoir was officially impounded on 17 February 2007, marking a significant shift in the local hydrology of the Junxi River. This impoundment created a standing body of water that alters the flow regime downstream and upstream, affecting sediment transport and water temperature profiles characteristic of the river ecosystem.

The environmental context of the Jiemian Dam involves the transformation of the Junxi River's natural state into a managed reservoir system. The concrete-face rock-fill design allows for a specific footprint and structural interaction with the river valley. The reservoir's creation impacts the aquatic environment by changing flow velocities and potentially affecting fish migration patterns and benthic habitats along the Junxi River. The operational status of the plant remains active, continuing to regulate water release for power generation purposes.

The location in Youxi County places the dam within a region where hydroelectric development is a key component of the local energy infrastructure. The 300 MW capacity contributes to the regional grid, utilizing the water resources of the Junxi River.

How does Jiemian Dam compare to other Chinese hydro projects?

The Jiemian Dam represents a specialized application of concrete-face rock-fill (CFR) technology within the broader landscape of Chinese hydropower infrastructure. Unlike the massive concrete gravity or arch dams that dominate national capacity statistics, CFR structures like Jiemian offer distinct engineering advantages for specific topographical and geological conditions. The dam, located on the Junxi River in Youxi County, Fujian Province, utilizes a rock-fill core faced with concrete slabs to withstand hydrostatic pressure, a design choice that often reduces concrete usage and construction time compared to traditional gravity dams. This technological classification places Jiemian among a growing cohort of CFR projects in China, which have been increasingly favored for mid-sized reservoirs where the flexibility of the rock-fill body can accommodate foundation settlement more effectively than rigid concrete structures.

In terms of scale, the Jiemian Dam’s installed capacity of 300 MW positions it as a medium-sized hydroelectric facility within the Chinese grid. While this output is substantial for a county-level project, it is modest when compared to the gigawatt-scale giants of the Yangtze River basin, such as the Three Gorges Dam or the Xiluodu Hydropower Station. However, Jiemian is not an outlier in its class; China hosts hundreds of hydroelectric plants with capacities ranging from 100 MW to 500 MW, many of which serve regional grids or feed into provincial networks in Fujian and neighboring Zhejiang. The 300 MW capacity is achieved through a power station that was commissioned in stages, with the first 150 MW generator coming online on 28 November 2007 and the second unit following in 2008. This phased commissioning strategy is typical for medium-sized hydro projects, allowing for operational revenue generation and grid integration testing before full capacity is reached.

Comparatively, the Jiemian Dam’s reservoir and catchment area are characteristic of the hilly terrain of southeastern China. The Junxi River, a tributary system in Fujian, provides the necessary flow regime to support consistent power generation, though it lacks the vast storage volume of major trunk-river dams. The construction period, which began in 2002 and saw the reservoir impounded by 17 February 2007, reflects a relatively rapid five-year build-out for a CFR structure. This timeline is competitive within the Chinese hydro sector, where construction efficiency is a key metric. The operational status of the dam remains active, contributing to the diversification of Fujian’s energy mix alongside larger thermal and emerging renewable projects. The choice of CFR technology at Jiemian underscores a strategic engineering decision to balance cost, material availability, and geological suitability, a pattern observed in many of China’s regional hydro developments outside the major river basins.

See also

• The Three Gorges Dam: Does it accelerate or delay the progress towards eliminating transmission of schistosomiasis in China?
• Shanghai Petrochemical: Operations, Ownership and Strategic Position
• Three Gorges Dam: Engineering, Operations and Environmental Impact
• Environmental flow management strategies based on the integration of water quantity and quality, a case study of the Baiyangdian Wetland, China
• Environmental flow assessment for improvement of ecological integrity in the Haihe River Basin, China