Formulations for the scattering properties of suspended sandy sediments for use in the application of acoustics to sediment transport processes

Multi-frequency acoustics backscattering has been used for over a decade, to quantitatively measure profiles of suspended sediment particle size and concentration, in the bottom 1-2 m above the seabed. Central to obtaining the sediment parameters from the backscattered signal is a description of the scattering characteristics of the particles in suspension. Therefore, formulations are required for the attenuation and backscattering properties of the suspended particles with size and acoustic frequency. There is no single formulation for these scattering properties and different researchers have used somewhat different expressions. However, these expressions are all based on a variation of sphere scattering, modified to fit available scattering data. Here we bring together all the published data on acoustic backscattering and attenuation by suspensions of sandy sediments. The aim is to provide coastal scientists, who use acoustics for sediment transport measurements, with simple expressions which best represent the observed scattering properties of sandy sediments.