Scattering of acoustic waves from rough seabeds: a comparison of two- and three-dimensional models

The seabed possesses variations in its material properties, layering structure, slope and roughness making prediction and analysis of sound propagation in shallow water highly complex. For certain frequency ranges, the effect of roughness becomes significant. Numerous models have been adopted to account for the scattering of acoustic waves by rough surfaces, including Kirchhoff approximation (for relatively large scales of roughness), small perturbation theory (for relatively small scales of roughness), and the small slope approximation. In this study, we have used the Kirchhoff approximation to model the scattering of acoustic waves, and the effects of the seabed roughness and slope angle of the seabed on the scattering characteristics are investigated. The results are compared with a numerical graphics processing unit (GPU)-accelerated finite element model incorporating roughness parameters (Root Mean Square height and correlation length) for rough, sloped seabed geometries (with gradients ranging from zero to twenty degrees) in shallow water environments. The effect of large-and small-scale roughness on sound propagation is investigated in two- and three-dimensional space.