Western Australia Chapter

Underwater noise from pile-driving: measurement, modelling, and mitigation

Dr Alec Duncan

Until a few decades ago, little thought was given to the environmental impacts of man-made underwater noise, but this has now changed, with a growing awareness of the importance of sound to marine animals resulting in a mounting concern about the possible detrimental effects of the underwater noise that we make on these animals. In Australia, this concern has considerable legislative backing in the form of the Environmental Protection and Biodiversity Conservation Act (EPBC Act), which makes it an offence to unduly interfere with endangered and migratory species, which includes whales, dolphins, dugong, and sea turtles.

It is unlikely to surprise anyone that pile-driving for the construction of ports and other marine facilities produces high levels of underwater noise. Regulators are certainly aware of this, and they now often require proponents of marine infrastructure projects that involve piling to include a consideration of the resulting underwater noise as part of their environmental impact assessments. The Centre for Marine Science and Technology (CMST) is often asked to assist in this process by carrying out measurement and/or modelling of underwater noise from pile driving, which turns out to be more complicated than one might imagine.

This talk will describe the characteristics of underwater noise from piling, and how the propagation of sound varies with such factors as water depth and seabed geology. Modelling methods will be described and there will be a brief overview of possible impacts on marine animals. Finally, there will be some discussion about the effectiveness of methods to reduce underwater noise from pile-driving.

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