An efficient model for prediction of underwater noise due to pile driving at large ranges

Modelling the sound levels in the water column due to pile driving operations nearby and out to large distances from the pile is crucial in assessing the likely impact on marine life. Standard numerical techniques for modelling the sound radiation from mechanical structures such as the finite element (FE) and boundary element method are not well suited to predict the sound field efficiently at large ranges. Models better suited for prediction of sound propagation in waveguides over large distances, such as wavenumber integration and ray tracing, require careful attention in order to capture the source characteristics of a complex source such as a pile radiating from both water and sediment. To circumvent these issues, a new hybrid model is proposed using a local FE model that accurately captures the source characteristics of the pile which is coupled to a normal mode based model for efficient evaluation of the sound propagation over large distances in a range dependent environment. The model is validated using the well-known solution for a point source in a Pekeris wave guide. Results are shown for a generic pile driving scenario that was used in the international benchmarking workshop COMPILE for underwater pile driving models.