Laboratory experiment for initiation of wood motion on mobile-bed by using IMU sensor

ABSTRACT   In recent years, Taiwan has suffered from large-scale sediment-related disasters frequently caused by climate change induced extreme rainfall events. Fresh wood was usually recruited with large-scale sediment-related disasters and trapped in channels. Once a flash flood occurs, wood accumulated in the river consequently travels, threatening the safety of structures in the river. Furthermore, driftwood forms log jams leading to river blockage and backwater, causing overflooding. Therefore, realizing the initiation of motion mechanism of driftwood helps prevent driftwood disasters.

According to previous studies on the initiation of wood motion, driftwood interacts with sediment and results in sliding, rolling, pivoting and floating motion modes dependent on discharge and riverbed conditions. To explore the motion mode of the initiation of wood motion on a mobile bed, this study conducts a flume experiment using driftwood equipped with an IMU (Inertial measurement unit) sensor that measures the posture of driftwood’s motion in the Eular Angle. According to the IMU’s data, the above four motion modes can be interpreted. Meanwhile, using the laser scanner to establish the digital elevation model and explore the correlation between sediment and driftwood motion on different mobile-bed conditions.