Okurodani Dam

Overview

The Okurodani Dam is a rock-fill embankment structure situated on the Oshirakawa River in Shōkawa, Gifu Prefecture, Japan. This hydroelectric infrastructure project serves as a key component of the regional water management and power generation network in the Chūbu region. The dam is located approximately 7 km (4.3 mi) west of the town of Shōkawa, providing strategic control over the river's flow for downstream utilization. The construction of the dam took place between 1969 and 1971, culminating in its operational status which has been maintained since its commissioning in 1971.

Integral to the Okurodani Dam system is an associated hydroelectric power station with an installed capacity of 21.2 MW. This power station is positioned about 3.5 km (2.2 mi) downstream from the main dam structure, optimizing the hydraulic head for energy production. The facility operates using water as its primary energy source, converting the potential energy of the stored water into electrical power for the local grid. The rock-fill construction method was selected for its stability and adaptability to the specific geological conditions of the Oshirakawa River valley.

The Okurodani Dam represents a mid-20th-century approach to hydroelectric development in Japan, focusing on reliable, steady power output. Its operational history since 1971 demonstrates the durability of rock-fill dam technology in the Japanese landscape. The facility continues to contribute to the energy mix of Gifu Prefecture, leveraging the natural topography of the region to generate electricity. The precise operator of the facility is not explicitly specified in the primary cited sources, though it functions as a critical node in the local hydroelectric infrastructure.

History and Construction

Its location is approximately 7 km (4.3 mi) west of Shōkawa. The dam serves as the primary water retention infrastructure for an associated hydroelectric power station. This power station is located about 3.5 km (2.2 mi) downstream from the dam itself. The facility is classified as a hydroelectric powerplant with a primary fuel source of water. It remains operational with an installed capacity of 21.2 MW. The construction of the dam and the development of the power station were executed as a coordinated infrastructure project during the late 1960s and early 1970s.

Construction Period

The construction of the Okurodani Dam began in 1969. The project involved the building of a rock-fill dam on the Oshirakawa River. Rock-fill dams are a common type of embankment dam construction, utilizing compacted rock and earth materials to create a robust barrier against the river flow. The construction phase spanned two years, concluding in 1971. This timeline reflects the period required to complete the civil engineering works necessary for the dam's structural integrity and water retention capabilities. The project was completed within the 1969–1971 window, establishing the physical foundation for the hydroelectric generation system.

Commissioning of the Power Station

The associated hydroelectric power station was commissioned in 1971. This commissioning date coincides with the completion of the dam construction, indicating a synchronized operational rollout. The power station is positioned downstream, leveraging the water flow regulated by the Okurodani Dam to generate electricity. The facility has a capacity of 21.2 MW. The operator of the plant is. The commissioning marked the entry of the Okurodani hydroelectric facility into the regional energy infrastructure. The dam and power station have remained in service since their initial completion in 1971. The operational status of the plant is currently listed as operational. The project represents a standard mid-20th century approach to hydroelectric development in Japan, focusing on rock-fill dam technology and downstream power generation.

Technical Specifications

The Okurodani Dam is classified as a rock-fill dam structure. It is situated on the Oshirakawa River, located approximately 7 km west of Shōkawa in Gifu Prefecture, Japan. The construction of the dam took place between 1969 and 1971.

This facility has an installed capacity of 21.2 MW. The power station was commissioned in 1971, coinciding with the completion of the dam construction. The primary energy source for the station is water from the Oshirakawa River.

Technical Data

The dam serves as the primary water retention structure for the hydroelectric facility. The rock-fill construction method utilizes compacted rock materials to form the main body of the dam, providing stability and water retention capabilities suitable for the Oshirakawa River's flow characteristics. The hydroelectric power station converts the potential energy of the retained water into electrical energy, contributing to the local grid in Gifu Prefecture.

The distance between the dam and the power station allows for a natural head difference, which is utilized in the hydroelectric generation process. The 3.5 km downstream location of the power station is a key design feature, enabling efficient water conveyance and energy extraction. The facility has remained operational since its commissioning in 1971, indicating sustained performance of both the dam structure and the power generation equipment.

The Oshirakawa River provides the consistent water flow necessary for the 21.2 MW capacity of the power station. This capacity level is typical for medium-sized run-of-river or reservoir-based hydroelectric projects in Japan, designed to supplement regional electricity demand. The rock-fill dam type is chosen for its adaptability to the local geological conditions and cost-effectiveness in construction.

Geography and Location

The structure is located approximately 7 km west of the town of Shōkawa. This positioning places the dam within the specific geographic context of the Oshirakawa River basin, which serves as the primary water source for the hydroelectric generation system. The dam itself is classified as a rock-fill dam, a construction type that utilizes compacted rock to form the main barrier across the river channel. This engineering approach is common for hydroelectric projects in the region, providing structural stability while managing the flow of the Oshirakawa River.

Dam and Power Station Layout

The hydroelectric infrastructure associated with the Okurodani Dam is not immediately adjacent to the reservoir but is positioned further along the river's course. This separation between the dam and the power house is a characteristic feature of run-of-river or reservoir-based hydroelectric schemes, allowing for the utilization of the natural gradient of the Oshirakawa River to generate hydraulic head. The 21.2 MW capacity of the station is derived from the water flow managed by the rock-fill dam upstream.

What is the role of rock-fill dams in Japan?

The Okurodani Dam utilizes rock-fill construction technology, a structural approach that plays a significant role in Japan's hydroelectric infrastructure, particularly in the mountainous terrain of Gifu Prefecture. Rock-fill dams are constructed primarily of compacted rock and gravel, often with an impervious core or upstream face to retain water. This method is well-suited to the Japanese landscape, where abundant local stone resources and steep river valleys provide ideal conditions for such structures. The use of rock-fill allows for flexibility in design and efficient use of materials, making it a practical choice for regions with varied geological conditions.

Geological Suitability in Gifu Prefecture

Gifu Prefecture, located in the Chūbu region of Honshu, is characterized by rugged topography and significant elevation changes, which are conducive to hydroelectric power generation. The Oshirakawa River, on which the Okurodani Dam is situated, flows through this complex terrain. Rock-fill dams like Okurodani are particularly effective in such environments because they can accommodate the natural settlement of the foundation and withstand seismic activity, a critical consideration in seismically active Japan. The dam's location approximately 7 km west of Shōkawa places it in an area where the geological stability and availability of rock materials support the long-term integrity of the structure.

Integration with Hydroelectric Operations

The Okurodani Dam is not merely a water retention structure but a key component of a hydroelectric power system. The associated 21.2 MW power station, located about 3.5 km downstream, leverages the head created by the dam to generate electricity. Rock-fill dams are often chosen for hydroelectric projects because they can be built relatively quickly and cost-effectively compared to concrete gravity dams, especially when local rock is abundant. The commissioning of the power station in 1971, following construction between 1969 and 1971, reflects the integration of engineering efficiency with energy production needs. This setup allows for consistent power generation, contributing to the regional energy grid while managing water flow in the Oshirakawa River basin.

Broader Context of Rock-Fill Dams in Japan

In the broader context of Japanese dam construction, rock-fill technology has been widely adopted for its adaptability and durability. Japan's diverse geography, ranging from the Japanese Alps to coastal plains, necessitates a variety of dam types. Rock-fill dams are particularly prevalent in mountainous prefectures like Gifu, where the natural landscape provides both the materials and the topographical advantages needed for effective water management and power generation. The Okurodani Dam exemplifies this approach, demonstrating how local geological features can be harnessed to create efficient, long-lasting hydroelectric infrastructure. This technology continues to be relevant in Japan's energy landscape, supporting both historical and modern hydroelectric projects.

How does the Okurodani hydroelectric station operate?

The Okurodani hydroelectric station operates as a downstream facility connected to the Okurodani Dam, a rock-fill structure situated on the Oshirakawa River in Gifu Prefecture, Japan. The power station was commissioned in 1971, following the dam’s construction period between 1969 and 1971. It has an installed capacity of 21.2 MW and is located approximately 3.5 km (2.2 mi) downstream from the dam structure. The dam itself is positioned about 7 km (4.3 mi) west of Shōkawa. The hydroelectric generation process relies on water stored and regulated by the rock-fill dam, which releases flow through a penstock system to drive turbines at the downstream power house. This configuration allows for controlled water discharge, optimizing energy production based on river flow conditions and storage levels in the Oshirakawa River basin.

Hydroelectric Generation Process

The 21.2 MW station utilizes the potential energy of water stored behind the Okurodani Dam. As water is released from the reservoir, it travels through a conduit or penstock to the turbines located at the downstream power station. The kinetic energy of the flowing water spins the turbine blades, which are connected to a generator that converts mechanical energy into electrical energy. The rock-fill dam serves as the primary water retention structure, ensuring a consistent supply of water to the power station. The distance of 3.5 km (2.2 mi) between the dam and the power station allows for a significant head difference, enhancing the efficiency of the hydroelectric generation process. The system is designed to operate continuously, adjusting water flow to meet energy demand while maintaining reservoir levels for future generation.

Location and Infrastructure

The Okurodani Dam and its associated power station are located in Gifu Prefecture, Japan. This geographic arrangement is typical for run-of-the-river or storage-based hydroelectric systems, where the dam regulates water flow and the downstream station captures energy. The rock-fill construction of the dam provides stability and water retention capacity, essential for consistent power generation. The proximity to Shōkawa facilitates access for maintenance and operational management, although specific details about the operator are not specified in the available sources.

Significance

The Okurodani Dam serves as a functional component of the hydroelectric infrastructure in Gifu Prefecture, Japan. As a rock-fill structure on the Oshirakawa River, it represents the mid-20th-century engineering approach to harnessing water resources for localized power generation. The dam is situated approximately 7 km (4.3 mi) west of Shōkawa, positioning it within the broader network of water management and energy production in the region. Its construction between 1969 and 1971 reflects the period's focus on developing reliable hydroelectric capacity to support regional energy demands. The associated hydroelectric power station, located about 3.5 km (2.2 mi) downstream from the dam, was commissioned in 1971, marking the operational start of this specific energy asset. With an installed capacity of 21.2 MW, the facility contributes to the energy mix of Gifu Prefecture, providing a steady source of renewable power derived from the flow of the Oshirakawa River. This capacity, while modest compared to larger national projects, is significant for local grid stability and energy supply in the immediate vicinity of Shōkawa. The dam's role extends beyond mere electricity generation; it also influences the hydrological characteristics of the river, affecting downstream water availability and potentially supporting local water management needs. The operational status of the dam remains active, indicating its continued relevance in the local energy infrastructure. As a mid-20th-century project, the Okurodani Dam exemplifies the engineering standards and technological choices of its era, utilizing rock-fill construction methods that were common for dams of similar scale and location. The integration of the dam and the downstream power station demonstrates a coordinated approach to maximizing energy output from the water resource. The commissioning in 1971 aligns with the broader timeline of hydroelectric development in Japan during the post-war economic expansion, where such projects were crucial for fueling industrial and residential growth. The facility's continued operation underscores the durability and effectiveness of the engineering solutions implemented during its construction. The Okurodani Dam and its power station remain a testament to the strategic planning and execution of hydroelectric projects in Gifu Prefecture, contributing to the region's energy resilience. The specific location on the Oshirakawa River highlights the importance of site selection in hydroelectric development, leveraging the natural topography and water flow to optimize energy production. The 21.2 MW capacity, while not among the largest in the country, provides a meaningful contribution to the local energy infrastructure, supporting the needs of the surrounding communities and industries. The dam's rock-fill construction method offers insights into the material choices and engineering practices of the late 1960s and early 1970s, reflecting the technological capabilities and economic considerations of the time. The ongoing operation of the facility indicates successful maintenance and management, ensuring that the initial investment continues to yield energy returns. The Okurodani Dam stands as a notable example of mid-20th-century hydroelectric engineering in Japan, with a lasting impact on the energy landscape of Gifu Prefecture. Its continued functionality highlights the enduring value of well-planned and executed infrastructure projects. The dam's role in the local energy infrastructure is a key aspect of its significance, providing a reliable source of power that supports the region's development and sustainability goals. The integration of the dam and power station on the Oshirakawa River demonstrates the effective use of natural resources for energy production, a principle that remains relevant in contemporary energy planning. The Okurodani Dam's history and operation offer valuable insights into the evolution of hydroelectric power generation in Japan, reflecting the technological and economic trends of the mid-20th century. The facility's contribution to the local energy mix underscores the importance of diversified energy sources for regional stability and growth. The dam's continued operation serves as a reminder of the long-term benefits of strategic infrastructure investment, providing a sustainable energy source for the communities in Gifu Prefecture. The Okurodani Dam and its associated power station remain a significant part of the region's energy infrastructure, with a legacy that extends beyond its initial construction period. The facility's role in the local energy landscape is a testament to the effectiveness of mid-20th-century hydroelectric engineering and planning. The Okurodani Dam's significance lies in its contribution to the energy security and development of Gifu Prefecture, providing a reliable and renewable source of power that supports the region's ongoing growth and sustainability efforts. The dam's operation and maintenance continue to reflect the engineering standards and practices of its time, ensuring that the facility remains a valuable asset to the local energy infrastructure. Its continued operation highlights the enduring value of well-designed and maintained infrastructure projects, providing a sustainable energy source for the region. The dam's role in the local energy infrastructure is a key aspect of its significance, contributing to the region's energy resilience and supporting the needs of the surrounding communities and industries. The Okurodani Dam and its power station remain a notable example of mid-20th-century hydroelectric engineering in Japan, with a legacy that continues to influence the region's energy planning and development.

See also

• Waste-to-energy incineration plants as greenhouse gas reducers: a case study of seven Japanese metropolises
• Tokyo Electric Power Company: Corporate Structure, Fukushima Crisis and Industry Position
• Kawagoe Power Station: Gas-Fired Infrastructure in Mie Prefecture
• Fukushima nuclear power plant accident and comprehensive health risk management
• Nuclear and Industrial Safety Agency: Regulatory History and Reform