Author(s): Muneyuki Aoki, Keita Saito
Linked Author(s): Keita Saito
Keywords: Pool-and-weir-fishway, gravel deposit, flow, vorticity, fish behavior
Abstract: The purposes of this study are to examine the hydraulics characteristics in the pools with gravel deposit and characteristics of fish behavior on it. To complete them, the experiments in the small pool-and-weir-fishway are done. The experiments have been carried out by using the small pool-and-weir-fishway in the laboratory, to measure the flow velocity, water depth and to observe the movement of real fish. The real fish used is Tribolodon hakonensis for the experiments. For one experiment, 10 Toribolodon hakonensis are used. Those average body lengths is 0. 085 (m). In these experiments, the attention is focused on flow in the pool with gravel deposit and fish behavior. Especially, fish behavior mainly depends on hydraulic quantity; flow velocity and water depth. The explanation of the experiments cases are as follow. Flow quantity of Run1 is 0. 008 (m3/s) and Run2 is 0. 016 (m3/s). Condition of Pools bed of Run1-1 and Run2-1 are without gravel. On another front, in the pools of Run1-2 and Run2-2 gravel is depositing. Real fish run up approximately 0. 02 (m) of on the bed or gravel. In case of Run2-1, real fish employ the unique movement of fish against the flow in the pool. However, in case of Run2-2, real fish stayed often on the gravel. In cases of Run1-2 and Run2-2 run-up ratio has decreased more than Run1-1 and Run2-1 because flow in pools decreased the plunging flow area by the gravel. Moreover, run-up ratio of Run1-2 is the worst. Additionally, vorticity of flow increased in the pool, especially on the gravel. If gravel is deposited in the pool-and-weir-fishway, fish cannot easily run-up in the pools. Because, plunging flow area is decreased and vorticity of flow is increased
Year: 2017