• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.75-85
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• 2008

The pale chub (Zacco platypus) is a dominant species that migrates locally and inhabits in rivers in Korea. The fish movement at confluences or hydraulic connections is very important especially for the life of small fish as pale chub. If main stream and off-channel habitats are connected with culverts, they would restrict the fish movement due to the high flow velocities and low depths. In foreign conturies, design flow conditions of fish friendly culvert, including flood flow capacity and fish-passage flow capacity, were assigned. Installation of culvert fishways is one way to improve the fish-passing capacity of culverts. On the contrary, in Korea, the design flow of culvert contains only the flood flow capacity. The effect of the fish passage with offset baffles was tested with the fixed velocity method in an experimental flume. As a result, An occasion velocity 1.2m/s, proportional success of pale chubs pass is maximum 20% improve than without baffle flume for energy dissipate. Offset baffle fishway(baffle height 5cm) provides that resting areas and/or a continuous channel of low velocity water in culverts. Especially, short baffle areas are domain where the pale chubs pass. And, FLOW-3D, a three dimentional numerical model, was used in order to evaluate detailed hydraulic characteristics and application possibility in a culvert fishway design.

• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.423-432
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• 2008

The local migration or movement behavior of fishes in streams are related to feeding, spawning, growing, dispersing, and refuging. The pale chub (Zacco platypus) is a dominant species that migrates locally and inhabits in river and stream in Korea. However, dams, weirs, culverts and other regulatory structures are physical barriers that limit fish movement and fragment habits and populations. If main stream and off-channel habitats are connected with culverts, they would restrict the small fish as pale chub movement due to the high flow velocities and low depths. But in Korea, there is no experimental study to evaluate the swimming performance of species in Korea. Therefore, it is difficult to proposed that design guidelines for pass fishes through culverts. The purpose of this experimental study is to evaluate the swimming performance of pale chubs. A series of swimming performance test has been used in both of the fixed velocity and the incremental velocity methods in an experimental flume. As a result, the critical swimming speed for pale chub(body length 8.9 cm) was found to be about 0.7 m/s. Therefore, the flow velocity for culvert design in the low flow condition should not be exceed the its swimming ability, especially 0.7 m/s for pale chubs(body length 8.9 cm). And the minimum depth for culvert design in the low flow condition should not be lower than the fish body height add a dorsal fin height.