Vann Jones (née Norman), E. C. and Rosser, N. J. and Brain, M. J. and Petley, D. N. (2015) 'Quantifying the environmental controls on erosion of a hard rock cliff.', Marine geology., 363 . pp. 230-242.
Linking hard rock coastal cliff erosion to environmental drivers is challenging, with weak relationships commonly observed in comparisons of marine and subaerial conditions to the timing and character of erosion. The aim of this paper is to bring together datasets to explore how best to represent conditions at the coast and to test relationships with erosion, which on this coast is primarily achieved via rockfalls. On the N. Yorkshire coast in the UK we compare a continuously monitored microseismic dataset, regionally monitored coastal environmental conditions, modelled at-cliff conditions and periodic high-resolution 3D monitoring of changes to the cliff face over a 2-year period. Cliff-top microseismic ground motions are generated by a range of offshore, nearshore and at-cliff sources. We consider such ground motions as proxies for those conditions that promote the occurrence of rockfalls and erosion. Both these data and modelled at-cliff water levels provide improved insight into conditions at, and wave energy transfer to, the cliff. The variability in microseismic, modelled and regionally-monitored environmental data derives statistically significant relationships with increases in the occurrence of rockfalls. The results demonstrate a marine control on the total volume and size characteristics of rockfalls. The strongest relationships found are with rockfalls sourced from across the entire cliff, rather than just at the toe, indicating that the marine influence, albeit indirectly, extends above and beyond the area inundated. These results identify failure mechanisms driving erosion, where a range of processes unique to the coast trigger failure, but in a manner beyond purely wave action at the cliff toe. Greater erosion occurs at the cliff toe. However, comparing water level inundation frequency, microseismic energy transfer and erosion, we observe that heights up the cliff that correspond with water levels associated with low frequency, high energy storms, or more frequent inundation, do not experience increased erosion. Our results describe the relationship between inundation duration, energy transfer and erosion of hard rock cliffs, and illustrate the relative intensity of erosion response to variations in these conditions. Implicitly our data suggests that in future, cliffed rocky coasts may be relatively quick to respond to changes in environmental forcing.
|Keywords:||Rocky coast, Coastal erosion, Coastal cliff, Cliff ground motion, Rockfall, Wave energy.|
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||http://dx.doi.org/10.1016/j.margeo.2014.12.008|
|Publisher statement:||NOTICE: this is the author’s version of a work that was accepted for publication in Marine Geology. 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 subsequently published in Marine Geology, 363, May 2015, 10.1016/j.margeo.2014.12.008.|
|Date accepted:||26 December 2014|
|Date deposited:||13 March 2015|
|Date of first online publication:||May 2015|
|Date first made open access:||17 August 2016|
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