Underwater sound from pile driving, what is it and why does it matter
Peter H. Dahl, Per G. Reinhall, Arthur N. Popper, Mardi C. Hastings and Michael A. Ainslie
Pile driving as used for in-water construction can produce high levels of underwater sound that has potential to produce physiological and/or behavioral effects on fish, benthic invertebrates, and marine mammals. There are two basic pile driving methods: impact pile driving where the pile is driven by strikes from a high-energy hammer, and vibratory pile driving where the pile is effectively vibrated into the sediment. Often both methods are used on the same pile. At ranges on the order of 10 m, and considering steel piles of diameter 0.75–1 m, vibratory pile driving produces underwater sound pressures of order 100–1000 Pa, which is often sustained for minutes. In contrast, each impact pile strike produces peak sound pressures on the order of 100 kPa, with effective duration of the sound from the strike being of order tens of milliseconds.Measurements made both far from the pile source (range many depths) and close-in (range of about 1–2 depths) for impact and vibratory pile driving are presented, along with examplesmodeling of such sound. We conclude by showing why such sounds matter to aquatic life; potential effects include injury at close range and behavioral changes, including evasion resulting in habitat loss at greater distance.
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