Performance of the Vectrino Profiler at the sediment–water interface

The Vectrino Profiler is increasingly recognized as a promising instrument for characterizing near-bed velocities and turbulence due to its high spatio-temporal resolution and velocity profiling range. However, its measurement performance in the vicinity of the bed (<10 mm) is not well documented. This study reports on the comparisons of mean velocity, turbulent kinetic energy, and power spectral density above various bed materials between the Vectrino Profiler and particle image velocimetry in a laboratory flume. Our analyses demonstrate that the bed interference adversely influences the measurements as close as 1.7–5 mm above the bed, depending on the bed material. We provide a criterion to identify the vertical extent of the interference region. Outside of the interference region, best agreement between the Vectrino Profiler and particle image velocimetry was found around the sweet-spot of the profiler where the observed differences were <6% for mean velocities and <10% for turbulent kinetic energy.