Assessment of the physical disturbance of the northern European Continental shelf seabed by waves and currents

Aldridge, J.N.; Parker, E.R.; Bricheno, L.M. ORCID: https://orcid.org/0000-0002-4751-9366; Green, S.L.; van der Molen, J.. 2015 Assessment of the physical disturbance of the northern European Continental shelf seabed by waves and currents. Continental Shelf Research, 108. 121-140. https://doi.org/10.1016/j.csr.2015.03.004

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Text © 2015 Elsevier B.V. This is the author’s version of a work that was accepted for publication in Continental Shelf Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was/will be published in Continental Shelf Research doi:10.1016/j.csr.2015.03.004 Aldridge_2014.pdf - Accepted Version Download (894kB) | Preview

Abstract/Summary

Natural seabed disturbance was quantified by estimating the number of days in a year that movement of the seabed occurred due to waves and currents. Disturbance over gravel substrates was based on the concept of a critical threshold for bed movement. For mud substrates disturbance was assessed on the basis of bed failure under extreme hydrodynamic stress. For sand beds the disturbance frequency was calculated by reference to the predicted occurrence of small scale bedforms using established relationships for estimating ripple and megaripple height. The method was applied to the northern European Continental Shelf (48°N to 58.5°N and 10°W to 10°E) using modelled annual wave and current forcing with a temporal resolution of one hour and spatial resolution of approximately 11 km. Highest levels of disturbance occurred in areas of high tidal stress where dune/megaripple type bedforms were predicted and in shallow regions exposed to waves with large fetch. However, the detailed distribution of disturbance showed a complex relationship between water depth, tidal stress, wave fetch and grain size. An assessment of the uncertainty in the results was made by use of a simple Monte Carlo approach. In most locations this indicated a large uncertainty in disturbance frequency values suggesting that present predictive relationships need improvement if assessments of natural disturbance are to be made with confidence. Nevertheless the results give a broad understanding of the location and intensity of natural physical bed disturbance and the ability to compare the relative intensity between different regions. This has applications to management of the seabed where human impacts have to be assessed in the context of the underlying natural disturbance. Recommendations are given for further research that might help decrease the uncertainty in natural disturbance prediction.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.csr.2015.03.004
ISSN:	02784343
Additional Keywords:	Seabed disturbance; Bedforms; Gravel; Sand; Mud; Modelling
NORA Subject Terms:	Marine Sciences
Date made live:	16 Sep 2015 12:11 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/511781

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