正会員 博(工) 九州工業大学准教授 工学部建設社会工学科(〒804-8550 北九州市戸畑区仙水町1-1) 2 フェロー会員 Ph.D. 九州工業大学教授 工学部建設社会工学科 3 学生員 九州工業大学大学院 工学研究科博士前期課程 4 学生員 九州工業大学 工学部建設社会工学科 Most of fishways constructed beside of weirs and dams in Japanese rivers belong to pool-and-weir type. Usually, a notch is placed at the weir. Ministry of Land, Infrastructure and Transport recommends that the ratio between the notch width and fishway one set to in the range between 0.17 and 0.20 without any verification. In this study, the notch ratio in

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... a pool-and-weir fishway was changed in the range between 0.1 and 0.7 and migration rates of ayu, Plecoglossus altivelis altivelis, were obtained with the aid of two sets of digital video cameras. Further, three components velocities were measured with a 3-D electromagnetic current meter. It was found that the migration rate changes with respect to the discharge, the migration rate increases with a decrease of the notch ratio and also that the most of migration positions over the weir are located near the side-wall. Those characteristics concern with the flow velocity and orientation area. The position of the orientation area concerns with the flow velocity.