Three-dimensional modelling of underwater noise produced by a bulk carrier vessel and estimation of its environmental impacta).

ABSTRACT

This study presents the results of three-dimensional (3D) propagation modeling of noise from a transiting bulk carrier vessel. In the simulated scenario, the surface vessel is moving past a bottom-mounted hydrophone system. Sound levels are estimated in decidecade frequency bands as the vessel transits past the hydrophone, and the simulation results are compared against real measured data. The modelling is performed using the program AMPLE, which is based on the wide-angle mode parabolic equation theory for simulating 3D broadband acoustic fields in a shallow sea. The model is used to investigate the effect of 3D phenomena on the surface vessel sound propagation. It is shown that an inaccuracy of the noise simulation associated with the use of a two-dimensional model can be as high as 7-10 dB for certain distances and for frequency bands over which a major part of the source energy is distributed. An approach to the selection of data-adjusted media parameters based on the Bayesian optimization is suggested, and the influence of the various parameters on the sound levels is discussed.