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Quantification of contemporary storm-induced boulder transport on an intertidal shore platform using Radio Frequency Identification (RFID) technology

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Extreme storm events are known to produce, entrain, transport and deposit sizable boulders along rocky coastlines. However, the extent to which these processes occur under moderate, fetch‐limited wave conditions is seldom considered. In this study we quantify boulder transport at a relatively sheltered location subjected to high frequency, low magnitude storm activity. This was achieved by deploying Radio Frequency Identification (RFID) tags within 104 intertidal limestone boulders ranging in size from fine to very coarse (intermediate axis: 0.27‐2.85 m). The study was conducted over three years (July 2015 ‐ July 2018) and encompassed numerous storm events. Tagged boulders were relocated during 17 field surveys and their positions recorded using Differential Global Positioning Navigation Satellite System (DGNSS).

On completion, we identified boulder displacement in 69% of the tagged array. The accrued boulder transport distance amounted to 233.0 m from 195 incidents of displacement including the movement of a boulder weighing an estimated 11.9 tonnes. Transport was not confined to autumn and winter storms alone as displacement was also recorded during summer months (April ‐ September) despite the seasonally reduced wave magnitude.

Boulder production by wave quarrying was documented in three tagged clasts confirming observations that the shore platform is actively eroding. Incidents of overturning during transport were also recorded including multiple overturning of clasts weighing up to 5 tonnes. We further identify a statistically significant difference (maximum p‐value: ≤0.03) between the transport distances attributed to constrained and unconstrained boulders suggesting the pre‐transport morphological setting exerts considerable control over boulder transport potential.

The findings establish low to moderate storm waves as a key component in the evolution of the study site. More broadly, we claim that high frequency, low magnitude storms regularly modify these overlooked rocky coastal locations suggesting the hydrodynamic capability at such sites may have been previously underestimated.
Original languageEnglish
JournalEarth Surface Processes and Landforms
Early online date5 Feb 2020
DOIs
Publication statusEarly online - 5 Feb 2020

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  • Hastewell_et_al-2020-Earth_Surface_Processes_and_Landforms

    Rights statement: This is the peer reviewed version of the following article: Hastewell, L., Inkpen, R., Bray, M., and Schaefer, M. ( 2020) Quantification of contemporary storm‐induced boulder transport on an intertidal shore platform using Radio Frequency Identification (RFID) technology. Earth Surf. Process. Landforms, which has been published in final form at https://doi.org/10.1002/esp.4834. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

    Accepted author manuscript (Post-print), 6.94 MB, PDF document

    Due to publisher’s copyright restrictions, this document is not freely available to download from this website until: 5/02/21

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