Terraced Fishway: Jointly Developed Patent Fishway with the Chubu Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism
The unique shape is effective for upstream migration! The terraced fishway has solved the issues faced by conventional fishways!
In traditional fish passes, there were challenges such as difficulties in guiding fish to upstream routes and the accumulation of sediment within the fish pass, which reduces its functionality. These issues are addressed by the unique terraced fish pass that utilizes natural stones. We also provide explanations about the terraced fish pass, consultations on fish pass design (including drawing creation and quantity calculation), proposals, and assistance, so please feel free to contact us. 【Features】 ■ Fish can ascend from any direction thanks to the 180-degree design, preventing fish from lingering. ■ It has a maintenance-free structure that prevents sediment accumulation inside the fish pass. ■ The unique structure can accommodate changes in water levels, allowing water to flow from the collection ditch beneath the solid floor during low water conditions. ■ By realizing the concrete secondary productization as terraced fish pass blocks, we have achieved stable quality and simple construction for the fish pass. ■ By installing it as an auxiliary fish pass next to existing protruding fish passes, fish ascension can be made more effective. ■ Research has confirmed that not only swimming fish like sweetfish and amago but also bottom-dwelling fish like red crucian carp and gobies, as well as aquatic insects, utilize it. *For more details, please request materials or view the PDF data from the download section.
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basic information
This is a fishway with a 180-degree opening that allows fish to ascend from both sides, featuring a high ascent effect. It is a unique slit-type fishway with pools made of cobblestones, enabling fish to navigate easily through various flow conditions according to their own stamina. Additionally, due to its distinctive pool depth of 20 cm, maintenance such as the removal of accumulated sediment inside the fishway is unnecessary, and inspections after floods show no sediment accumulation. It has also been confirmed that the fishway's functionality is adequately maintained. We have developed fishway blocks with dimensions of 1m in depth, 1.5m in width, and a thickness of 20cm to 35cm, which are available for use. In the case of on-site construction, there are issues such as insufficient fixation of cobblestones during compaction, variations in cobblestone arrangement, and inconsistencies in quality depending on the contractor. By manufacturing these as secondary products in the form of fishway blocks, we can ensure the quality of the fishway after construction and also shorten the construction period. They have been adopted by the Ministry of Land, Infrastructure, Transport and Tourism, various prefectures, and municipalities, with numerous construction achievements. We are available to assist with design and proposals, so please feel free to contact us.
Price information
Please contact us. *Prices may vary depending on the transportation location, so feel free to reach out to us.
Delivery Time
※The delivery date may vary depending on the quantity, so please feel free to contact us.
Applications/Examples of results
【Purpose】 It alleviates a drop of about 2 meters at river dams and is effective for fish migration. Additionally, by installing it next to existing fish passages, it can further promote fish ascension and the movement of aquatic organisms as a supplementary fish passage. 【Track Record】 There are many adoption cases in various government agencies, including the Ministry of Land, Infrastructure, Transport and Tourism, as well as in Gifu Prefecture, Hokkaido, Saitama Prefecture, Yamanashi Prefecture, Nara Prefecture, and Kumamoto Prefecture.
Detailed information
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Fish can ascend from anywhere. Since fish can ascend from any point within the 180° opening, it prevents fish from stagnating. The terraced fishway has a 180-degree entrance, allowing fish to ascend from anywhere within the fishway. In the ascent survey conducted after the installation of the fishway, it was confirmed that about 70% of the aquatic organisms (swimming fish, bottom-dwelling fish, aquatic insects, etc.) that ascended through the entire fishway did so from the left and right fan-shaped sections, and it was also confirmed that fish ascend without stagnating.
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Maintenance-free structure that prevents sediment accumulation The water depth of the pool during normal water levels is set to approximately 20 cm, with a width of about 80 cm, making it shallow and narrow. Both sediment and stones are swept away by the turbulent flow, leaving no space for sediment to accumulate. The water depth of the terraced fishway pool is set to about 20 cm, which is very shallow compared to other fishways that have depths of 35 to 80 cm. During floods, the sediment that flows out is flushed downstream, preventing any accumulation of sediment. Therefore, the removal of accumulated sediment is unnecessary.
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Responding to changes in river flow, during low water periods, water is drawn from the collection ditch beneath the riverbed. Natural rivers constantly experience changes in flow. The stepped fishway is designed with a steeper gradient in the transverse direction (across the flow of the river) than in the longitudinal direction (the direction of the river flow) to facilitate the gathering of water. This design ensures that even when the flow decreases, the water does not spread out shallowly, but instead collects and flows into the "collection ditch" beneath the riverbed, serving as "calling water" that encourages fish to migrate upstream.
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Concrete secondary products are created to ensure the quality of fish passages. When placing cobblestones and other materials on-site, using a vibrator can cause the cobblestones to sink, making it difficult to set them at the desired height, which poses a risk of lowering the quality of the fish passage. The terraced fish passage has been developed using natural cobblestones as concrete secondary products, known as terraced fish passage blocks, ensuring rapid construction and maintaining the quality required for fish passages. The terraced fish passage blocks come in various shapes, and the combination of these products forms the terraced fish passage.
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Company information
Yamachin Group is supported by the understanding and guidance of many people, and with the corporate philosophy of "creativity, ingenuity, and tireless effort," we are committed to contributing to the local community alongside the development of our company. By engaging in civil engineering projects that involve nature, we consider how to conduct construction with respect for the natural environment, learn many lessons from it, and aim to create a "distinctive company" among numerous construction contractors. In 1991, we established the Environmental Division and began "environmental conservation activities unique to the construction industry," developing and proposing various environmental products such as natural stone block series for river environment conservation, various fishway series tailored to installation locations, and the "Hybrid Eco Pump," an underwater pump that operates without electricity. We have worked on promoting and raising awareness of environmentally friendly construction methods. Thanks to this, we have been adopted in numerous projects, and we are grateful to be contributing to environmental conservation. Yamachin Group will continue to take on challenges through the construction industry, working on "proposals dedicated to the natural environment of our hometown" and contributing to global environmental conservation.