Novel high-frequency acoustic monitoring of streamflow-turbidity dynamics in a gravel-bed river during artificial dam flush

To assess the dynamics of rivers, a reliable characterization of river streamflow during unsteady flow regimes is of paramount importance. In this work, we aimed at investigating the characteristics of turbidity-discharge (T-Q) dynamics corresponding to annual artificial dam flush release in a mountainous stream. Two methods for evaluating discharge were used in this study: the classical rating curve and the fluvial acoustic tomography (FAT) system that was developed by Hiroshima University. Interestingly, during dam flush, the discharge records obtained by FAT showed striking features of unsteady streamflow behavior, such as discharge shoulders and, in some events, secondary discharge peaks. According to the T-Q hysteresis loops, the common type of T-Q observed patterns were anticlockwise loops. During the studied DF events, sediment was supplied by river banks located at different sites along the river channel.