Overview
The Shimokotori Dam is a rock-fill hydroelectric facility located in Gifu Prefecture, Japan. Situated on the Shimokotori River, the structure is positioned approximately 15 km west of the town of Hida. The dam serves as the primary water retention and diversion structure for a hydroelectric power generation system operated by Kansai Electric Power Company. The facility is currently operational and has been a component of the regional energy infrastructure since its commissioning in 1973.
The primary function of the Shimokotori Dam is hydroelectric power generation. Water stored in the dam’s reservoir is diverted through an 8.5 km long headrace tunnel to a power station located northeast of the dam structure. This configuration allows for efficient energy production by utilizing the elevation difference between the reservoir and the turbine hall. The power station has an installed capacity of 142 MW, contributing to the electrical grid managed by Kansai Electric Power Company. After passing through the turbines, the water is discharged into the Jinzū River, integrating the facility into the local hydrological system.
Construction of the Shimokotori Dam began in 1970, reflecting the mid-20th century expansion of hydroelectric infrastructure in Japan’s mountainous regions. The project was completed in 1973, with the power station becoming operational in May of that year. The dam’s design as a rock-fill structure is typical for the terrain, allowing for flexibility and stability in the hilly landscape of Gifu Prefecture. The facility has remained under the ownership and operational control of Kansai Electric Power Company since its inception, maintaining consistent service for over five decades.
The Shimokotori Dam exemplifies the integration of natural water resources with engineered systems to produce renewable energy. Its location on the Shimokotori River and its connection to the Jinzū River highlight the strategic use of topography for power generation. The 8.5 km headrace tunnel is a critical component of the system, enabling the transport of water from the reservoir to the turbines with minimal energy loss. This infrastructure supports the regional demand for electricity while leveraging the consistent flow of the river system in Gifu Prefecture.
Technical Specifications
The Shimokotori Dam functions as a critical structural component of a hydroelectric power generation system located in Gifu Prefecture, Japan. The facility is classified as a rock-fill dam, a construction method that utilizes a core of impervious material surrounded by layers of rock to maintain structural integrity against the hydraulic pressure of the reservoir. The primary engineering objective of the dam structure is to regulate water flow and create a reservoir to facilitate hydroelectric power generation. The water stored in the reservoir is not used solely for local irrigation or municipal supply but is primarily diverted to drive turbines at the associated power station.
Hydraulic Infrastructure and Power Station
The hydroelectric system relies on a significant diversion infrastructure to transport water from the reservoir to the generating units. Water from the Shimokotori Dam reservoir is channeled through a headrace tunnel that extends for 8.5 km (5.3 mi). This tunnel serves as the primary conduit, conveying water under pressure to the power station, which is located northeast of the dam structure. The length of the headrace tunnel is a key factor in determining the hydraulic head available to the turbines, influencing the overall efficiency and output of the power station. The power station itself has an installed capacity of 142 MW, providing a substantial contribution to the regional energy grid. The facility is owned and operated by the Kansai Electric Power Company, a major utility provider in western Japan.
After passing through the turbines in the power station, the water is discharged into the Jinzū River. This outflow location indicates that the system utilizes a diversion scheme where the water travels from the Shimokotori River basin to the Jinzū River basin, effectively transferring hydraulic energy across different topographical features. The operational status of the power station is currently active, having been commissioned in May 1973. The construction of the dam began in 1970 and was completed in 1973, marking a relatively swift development timeline for the project. The integration of the rock-fill dam, the 8.5 km headrace tunnel, and the 142 MW power station represents a coordinated engineering effort to harness the potential energy of the Shimokotori River for electricity production.
| Technical Parameter | Value |
|---|---|
| Dam Type | Rock-fill |
| Location | Shimokotori River, Gifu Prefecture, Japan |
| Distance from Hida | 15 km (9.3 mi) west |
| Headrace Tunnel Length | 8.5 km (5.3 mi) |
| Power Station Capacity | 142 MW |
| Operator | Kansai Electric Power Company |
| Discharge River | Jinzū River |
| Construction Start | 1970 |
| Construction Completion | 1973 |
| Commissioning Date | May 1973 |
| Operational Status | Operational |
Construction History
The construction of the Shimokotori Dam represents a focused engineering effort to harness the hydroelectric potential of the Shimokotori River in Gifu Prefecture, Japan. Groundbreaking for the project occurred in 1970, initiating the development of a rock-fill dam structure designed primarily for power generation. The construction phase spanned three years, culminating in the completion of the dam structure in 1973. This timeline reflects the standard duration for mid-sized hydroelectric infrastructure projects in the Japanese Alps region during that era, balancing geological surveying, material sourcing, and the complex logistics of building in a mountainous terrain approximately 15 km west of Hida.
The dam is constructed as a rock-fill type, a choice dictated by the local geology and the need for a robust barrier capable of managing the water flow from the Shimokotori River. This structural design allows for the creation of a reservoir that serves as the primary water source for the associated power station. The engineering work involved not only the dam itself but also the critical diversion infrastructure required to transport water from the reservoir to the turbine hall. Specifically, an 8.5 km long headrace tunnel was constructed to channel water from the dam site to the power station, which is located northeast of the dam structure. This tunnel is a vital component of the hydroelectric system, ensuring efficient water delivery under pressure to the generators.
Operational status for the facility was achieved in May 1973, marking the official start of power generation for the Kansai Electric Power Company. The power station, with an installed capacity of 142 MW, began discharging water into the Jinzū River, integrating the Shimokotori hydro system into the broader regional grid. The rapid transition from the start of construction in 1970 to full operation in May 1973 demonstrates the efficiency of the project management and engineering execution. The facility remains operational, continuing to provide renewable energy to the Kansai region. The involvement of the Aoki Corporation, noted in project records, highlights the collaborative effort between the primary owner, Kansai Electric Power Company, and specialized construction firms to deliver the infrastructure on schedule. This project stands as a key component of the hydroelectric infrastructure in Gifu Prefecture, leveraging the natural topography to generate consistent power output.
How does the Shimokotori hydroelectric system work?
The Shimokotori hydroelectric system operates as a classic diversion scheme, utilizing the natural topography of Gifu Prefecture to generate power. The process begins at the Shimokotori River, where a rock-fill dam creates a reservoir to regulate water flow. This infrastructure is situated approximately 15 km west of Hida, providing the necessary elevation head for the downstream power station.
Water Diversion and Headrace Tunnel
Unlike run-of-the-river systems where water passes directly through turbines, the Shimokotori plant relies on a significant lateral diversion. Water from the reservoir is channeled into a headrace tunnel that spans 8.5 km in length. This tunnel transports the water from the Shimokotori River basin toward the power station, which is located northeast of the dam structure. The use of a tunnel minimizes evaporation losses and allows for a more controlled flow rate reaching the turbines, optimizing the hydraulic efficiency of the 142 MW facility.
Power Generation and Discharge
The diverted water enters the power station, driving the turbines to produce electricity for the Kansai Electric Power Company grid. The plant has been operational since May 1973, following the completion of construction that started in 1970. This discharge point is distinct from the intake river, meaning the Shimokotori River's flow is partially or fully diverted depending on operational needs, while the Jinzū River receives the tailwater. This configuration allows the system to leverage the elevation difference between the dam site and the Jinzū River valley to maximize energy output.
Why it matters
The Shimokotori Dam serves as a critical node within the Kansai Electric Power Company’s regional hydroelectric infrastructure, specifically designed to optimize energy generation in the mountainous terrain of Gifu Prefecture. Its primary significance lies in its strategic location on the Shimokotori River, approximately 15 km west of Hida, which allows for an efficient diversion system that maximizes hydraulic head and power output. The facility is not merely a local water management structure but a dedicated energy asset that contributes 142 MW of capacity to the regional grid, providing a reliable source of baseload and peaking power for the Kansai area.
Strategic Diversion and Efficiency
The engineering design of the Shimokotori Dam highlights its importance in regional energy planning. Rather than relying solely on the immediate flow of the Shimokotori River, the dam utilizes a sophisticated diversion system. This configuration allows the facility to harness the elevation difference effectively, converting potential energy into electrical power with high efficiency. The discharged water eventually flows into the Jinzū River, integrating the hydroelectric cycle into the broader watershed management of the region. This diversion approach is characteristic of modern hydroelectric projects in Japan’s central highlands, where maximizing the use of limited water resources is essential for consistent power generation.
Role in the Kansai Grid
Operated by Kansai Electric Power Company, the Shimokotori Dam has been a stable contributor to the energy mix since its commissioning in 1973. The power station became operational in May 1973, shortly after the completion of the rock-fill dam construction which began in 1970. For over five decades, the facility has provided consistent hydroelectric output, supporting the grid stability of Gifu Prefecture and the wider Kansai region. In a landscape where renewable energy integration is increasingly vital, the 142 MW capacity of the Shimokotori power station offers a dependable, low-carbon energy source. Its long-term operational history underscores the durability of its rock-fill construction and the strategic foresight of Kansai Electric Power Company in developing infrastructure that continues to meet regional energy demands well into the 21st century. The dam’s continued operation reflects its enduring value in balancing the load on the regional grid, particularly during peak demand periods.
Geographic Context
The Shimokotori Dam is situated in Gifu Prefecture, Japan, positioned on the Shimokotori River. The facility is located approximately 15 km (9.3 mi) west of the city of Hida, placing it within a specific geographic context defined by the topography of the region and the flow of local waterways. This location is critical to the operational mechanics of the hydroelectric power plant, as the dam serves as the primary intake point for the water that drives the generation process. The dam itself is constructed as a rock-fill structure, a design choice that interacts directly with the geological characteristics of the Shimokotori River valley.
Hydrological Systems and Water Diversion
The operation of the Shimokotori hydroelectric power plant relies on the precise management of water from two distinct river systems: the Shimokotori River and the Jinzū River. The primary source of the water is the Shimokotori River, where the rock-fill dam creates a reservoir. From this reservoir, the water is not immediately discharged back into the same riverbed at the same elevation. Instead, it is diverted through a dedicated infrastructure network designed to maximize the potential energy of the water.
This diversion is achieved via an 8.5 km (5.3 mi) long headrace tunnel. The length and direction of this tunnel are key geographic features of the project, connecting the intake point to the generation facility. The power station, with a capacity of 142 MW, utilizes the water flow for hydroelectric power generation before releasing it into a different water body.
This discharge point marks the end of the water's journey through the immediate power generation cycle of the Shimokotori facility. The involvement of the Jinzū River is a defining characteristic of the plant's geographic footprint, distinguishing it from run-of-the-river plants that might discharge directly back into the source river. The interaction between the Shimokotori River as the source and the Jinzū River as the discharge point illustrates the complex water management required for this specific hydroelectric infrastructure in Gifu Prefecture.
The geographic separation between the dam on the Shimokotori River and the power station's discharge into the Jinzū River underscores the engineered nature of the site. The 15 km distance from Hida city places the facility in a relatively accessible yet distinct location, leveraging the natural elevation differences in the region to facilitate the flow of water through the 8.5 km tunnel. These geographic and hydrological details are fundamental to understanding the operational context of the Shimokotori Dam and its associated 142 MW power station, which has been operational since May 1973 under the ownership of Kansai Electric Power Company.