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Sediment‐generated noise and bed stress in a tidal channel
Author(s) -
Bassett Christopher,
Thomson Jim,
Polagye Brian
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/jgrc.20169
Subject(s) - noise (video) , geology , inlet , sediment , ambient noise level , turbulence , seabed , stress (linguistics) , acoustics , geotechnical engineering , sound (geography) , oceanography , geomorphology , meteorology , physics , linguistics , philosophy , artificial intelligence , computer science , image (mathematics)
Tidally driven currents and bed stresses can result in noise generated by moving sediments. At a site in Admiralty Inlet, Puget Sound, Washington State (USA), peak bed stresses exceed 20 Pa. Significant increases in noise levels are attributed to mobilized sediments at frequencies from 4–30 kHz with more modest increases noted from 1–4 kHz. Sediment‐generated noise during strong currents masks background noise from other sources, including vessel traffic. Inversions of the acoustic spectra for equivalent grain sizes are consistent with qualitative data of the seabed composition. Bed stress calculations using log layer, Reynolds stress, and inertial dissipation techniques generally agree well and are used to estimate the shear stresses at which noise levels increase for different grain sizes. Regressions of the acoustic intensity versus near‐bed hydrodynamic power demonstrate that noise levels are highly predictable above a critical threshold despite the scatter introduced by the localized nature of mobilization events.