Modelling Pile-Driving Sound and Mitigation in Realistic Environments

Impact pile driving is a transient anthropogenic underwater sound source that can potentially affect marine life. Mathematical modelling tools are essential for predicting sound levels before installing new offshore wind farms. Different modelling approaches are required for modelling the sound generation in proximity to the pile, the mitigation of the noise with the use of air-bubble curtains, and the sound propagation at a larger distance. In addition, the interface and coupling between the different modelling approaches should be carefully considered without losing important details. In this work, a multi-model approach for estimating pile-driving sound in a realistic environment is described. The shortrange predictions (up to 750 m) provide detailed spectral and temporal output in various metrics in the water (acoustic pressure, particle velocity) and the seabed (stress and displacement vectors). For the long-range predictions beyond 750 m, only the acoustic pressure metric is calculated, including the range-dependent properties of the acoustic environment. Based on the combination of short- and long-range models, sound maps can be created to identify the contribution of the pile driving to the underwater soundscape.