Axial-flow hydropower plants, commonly equipped with Kaplan turbines, are ideal for sites with low to medium head and large flow rates. These turbines are widely used in run-of-river and low-head dam projects due to their high efficiency and adaptability. The success of such hydropower installations relies heavily on well-designed and carefully executed civil works, which form the foundation for turbine performance, operational stability, and safety.
1. Site Preparation and River Diversion
Before any major construction begins, site preparation is essential. This includes clearing the construction area, setting up access roads, and establishing a river diversion system to reroute water and create a dry working environment. Cofferdams—temporary enclosures built within or across the river—are often used to isolate the construction site from water.
2. Intake Structure
The intake structure controls the entry of water into the power plant and ensures debris-free, stable flow to the turbine. It includes trash racks, gates, and sometimes sediment flushing facilities. Proper hydraulic design is critical to prevent vortex formation, minimize head losses, and protect the turbine from floating debris.
3. Penstock or Open Channel
Depending on the layout, water from the intake is conveyed to the turbine via penstocks (closed pipes) or open channels. In many axial-flow designs—especially in low-head plants—an open intake connected directly to the turbine is used. Structural stability, flow uniformity, and minimization of hydraulic losses are key concerns during this stage.
4. Powerhouse Structure
The powerhouse houses the turbine-generator unit, control systems, and auxiliary equipment. For Kaplan turbines, which are usually installed vertically, the powerhouse must be designed to support large axial loads and dynamic forces. Vibrational stability, waterproofing, and ease of access for maintenance are critical aspects of the structural design.
5. Draft Tube and Tailrace
The draft tube plays a vital role in recovering kinetic energy from the water exiting the turbine. A well-designed draft tube increases overall efficiency. The tailrace channel conveys water safely back to the river. Both structures require precise shaping to reduce turbulence and backwater effects.
6. Control Room and Auxiliary Buildings
Apart from the main structures, civil works also include the construction of control rooms, staff quarters, workshops, and other operational buildings. These facilities ensure reliable plant operation and long-term maintenance.
7. Environmental and Geotechnical Considerations
Soil investigations, slope stabilization, erosion control, and environmental protection are essential parts of civil planning. Proper drainage systems, fish passages (where required), and landscaping work help minimize the environmental impact of the project.
The civil engineering component of an axial-flow hydropower plant is fundamental to its overall performance and longevity. Each structure—from the intake to the tailrace—must be carefully designed and constructed to withstand hydrological forces, geological conditions, and operational demands. Close collaboration between civil engineers, hydropower equipment suppliers, and environmental experts is key to delivering a safe, efficient, and sustainable hydropower solution.
Post time: Jun-11-2025
