Scattering from suspended sediments having different and mixed mineralogical compositions: comparison of laboratory measurements and theoretical predictions.

Laboratory measurements of the acoustic scattering properties of aqueous suspensions of non-cohesive sands having different and mixed mineralogical compositions are presented. Four different types of sand are examined: quartz, crushed shell, magnetite, and muscovite mica. The experimental data obtained for each type of sand are compared with theoretical scattering predictions for spheres having the same physical properties.

Acoustic inversions for measuring boundary layer suspended sediment processes.

Although sound has been applied to the study of sediment transport processes for a number of years, it is acknowledged that there are still problems in using the backscattered signal to measure suspended sediment parameters. In particular, when the attenuation due to the suspension becomes significant, the uncertainty associated with the variability in the scattering characteristics of the sediments in suspension can lead to inversion errors which accumulate as the sound propagates through the suspension. To study this attenuation propagation problem, numerical simulations and laboratory experiments have been used to assess the impact unpredictability in the scattering properties of the suspension has on the acoustically derived suspended sediments parameters.

Measurements and inversion of acoustic scattering from suspensions having broad size distributions.

Measurements are presented from a multi-frequency acoustic backscatter study of aqueous suspensions of irregularly shaped quartz sediments having broad particle size distributions. Using the backscattered sound from a homogenous suspension, measurements of the ensemble backscatter form function and ensemble normalized total scattering cross section were obtained. Three different size distribution types are examined; namely Gaussian, log-normal, and bi-modal distributions, each covering a range of particle sizes similar to those observed in sandy marine environments near the seabed.