Perspectives of ongoing acoustic developments for measuring sediment dynamics

Sediment entrainment, transport, and deposition over bedforms can be highly dynamic with strong spatially temporal variability. To probe the multi-scaled processes of sediment transport, there has been continuing developments of instrumentation to obtain high resolution measurements of near-bed sediment dynamics. Such observations are used for both the development and assessment of process based sediment transport modeling. Here, results are reported from studies on developing high resolution acoustic instruments, deployed to make co-located observations of bedforms, the near-bed and suspended concentration fields, and the horizontal and vertical components of intra-wave and turbulent flows. To evaluate the instruments, a series of bottom boundary layer measurements were collected over sandy sediments under differing conditions. The acoustic instruments under examination consisted of a Bedform and Suspended Sediment Imager, BASSI, a three dimensional acoustic ripple profiler, 3D-ARP, and high resolution Acoustic Concentration and Velocity Profilers, HR-ACVP. The results obtained from the instruments are used to illustrate ongoing developments in acoustics and its expanding capability for studying the dynamics of near-bed sediment transport processes.