Author(s): Daiki Akema; Muneyuki Aoki
Linked Author(s): Muneyuki AOKI
Keywords: Spur dike; Flood control structures; River environmental; Fish behavior; Tribolodon hakonensis
Abstract: This study focused on the environmental functions of flood control structures. Especially, we focused on the spur dikes in this study. The spur dikes are a traditional river construction method in Japan. The purposes of this study were clarified the fish behavior regarding the flow around the spur dikes by difference in longitudinal interval. The experiments were to observe the behavior of real fish, to measure the flow velocity and the water depth. The columns were changed longitudinal interval and arrangement. The real fish used in the experiments are Tribolodon hakonensis. The average body length of the fish is 8.6(cm) (6.7 to 10.2(cm)). The water temperature during the experiments was 18.3 to 24.5(℃). The results are show below. 1) There was a tendency for the fish to use the immediately downstream of the column for a long time. Because the flow velocity immediately downstream of the column was the flow velocity that fish can swim for a long time. 2) The time for the fish to swim in the group of columns was 10 times longer in case the interval between the column was wide. Because the area of flow velocity that fish can swim for a long time has expanded. The flow velocity downstream group of columns is 70(%) degree less than that upstream of group of columns. Therefore, it is appeared that the flood control function of the group of columns used in this study has been secured.
Year: 2020