| This study aims to clarify the transport of sediment and driftwood immediately upstream from fishway in mountain streams、 physical model experiments were conducted under the unsteady flow、 and the transport of sediment and driftwood immediately upstream from fishway was investigated (Figure 1.).[*][*]In this study、 we found in the ancillary experiments that when the water level was higher than the top of inlet section of the fishway、 the flow rate passing through the inlet decreased、 and the final experiment was conducted based on an inlet section with an open structure ((H-s)/h=1.00).[*][*]The major findings of this study are as follows.[*][*]・The transport of sediment was shown immediately upstream from the fishway. In particular、 in the case of (l-ba)/b=2.0、 when L/b=1.5 was compared with L/b=4.5、 the sediment condition immediately upstream from the fishway was considerably different、 and sediment was not confirmed immediately upstream from the fishway in the case of L/b=1.5 (Figure 2.).[*][*]・The transport of driftwood was shown immediately upstream from the fishway. In particular、 in the case of (l-ba)/b=2.0、 when L/b=1.5 was compared with L/b=4.5、 the velocity vector of the water surface and trace of the driftwood were considerably different. In the case of L/b=1.5、 the separated flow at the toe of the spur dike approached the overflow section directly、 because the spur dike was near the side wall of the Sabo dam、 and all driftwood models were discharged from the overflow section (Figure 3.). |
