An exploratory numerical model of rocky shore profile evolution

Matsumoto, Hironori; Dickson, Mark E.; Kench, Paul S.

doi:10.1016/j.geomorph.2016.05.017

Cited by 45 publications

(78 citation statements)

References 71 publications

(66 reference statements)

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“…The numerical model This paper uses the numerical model of rocky shore profile evolution, which considers both wave and weathering processes, described by Matsumoto et al (2016aMatsumoto et al ( , 2016b. It is based on an exploratory modelling approach (Murray, 2003(Murray, , 2007, in which a limited number of processes are selected and mathematically represented in a simplified manner, with the overarching aim of increasing the clarity of insights that the model can produce.…”

Section: Methodsmentioning

confidence: 99%

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Matsumoto

Dickson

Kench

2018

Earth Surf Processes Landf

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In this paper we use a numerical model to explore the relative dominance of two main processes in shore platform development: wave erosion; weathering due to wetting and drying. The modelling approach differs from previous work in several aspects, including: the way that it accounts for weathering arising from gradual surficial intertidal rock degradation; subtidal profile shape development; and the consideration of a broad erosion parameter space in which, at either end of the erosion spectrum, shore platform profiles are produced by waves or weathering alone. Results show that in micro‐tidal settings, wave erosion dominates the evolution of (i) shore platforms that become largely subtidal and (ii) sub‐horizontal shore platforms that have a receding seaward edge. Weathering processes dominate the evolution of sub‐horizontal shore platforms with a stable seaward edge. In contrast, sloping shore platforms in mega‐tidal settings are produced across the full range of the process‐dominance spectrum depending on the how the erosional efficacy of wave erosion and weathering are parameterized. Morphological feedbacks control the process‐dominance. In small tidal environments wave processes are strongly controlled by the presence/absence of an abrupt seaward edge, but this influence is much smaller in large tidal environments due to larger water depths particularly at high tides. In large tidal environments, similar shore platform profile geometries can be produced by either wave‐dominant or weathering‐dominant process regimes. Equifinality in shore platform development has been noted in other studies, but mainly in the context of smaller‐scale (centimetre to metre) erosion features. Here we draw attention to geomorphic equifinality at the scale of the shore platform itself. Progress requires a greater understanding of the actual mechanics of the process regimes operating on shore platforms. However, this paper makes a substantial contribution to the debate by identifying the physical conditions that allow clear statements about process dominance. © 2018 John Wiley & Sons, Ltd.

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Section: Methodsmentioning

confidence: 99%

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Matsumoto

Dickson

Kench

2018

Earth Surf Processes Landf

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“…Dynamic shore profile evolution models (e.g. Sunamura, 1992;Anderson et al, 1999;Trenhaile, 2000;Walkden and Hall, 2005;Matsumoto et al, 2016) predict that coasts tend towards steady state, whereby rapid cliff retreat widens shore platforms and the resultant increased wave energy dissipation reduces cliff retreat rates and increases erosion of the shore platform. We coupled predictions of 10 Be production to a dynamic shore profile evolution model (RoBoCoP; see Sect.…”

Section: Transient Shore Platform Developmentmentioning

confidence: 99%

“…These isotopes have the potential to yield rates of cliff recession and shore-platform erosion over millennial timescales . These records will provide a long-term context for historical and present rates of cliff recession and facilitate the calibration of dynamic models of shore platform erosion and cliff recession (Trenhaile, 2000;Walkden and Hall, 2005;Ashton et al, 2011;Matsumoto et al, 2016). The erosion of rocky coastlines is the result of a dynamic suite of processes that operate at the coast (Sunamura, 1992;Kennedy et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Long-term records of cliff retreat in response to relative sea level (RSL) change are required in order to predict how coastal erosion may proceed into the future in the face of anticipated RSL rise and increased storminess. Yet, by their very nature, eroding coastlines leave scant evidence of any former state, and their form reflects little about their longterm erosional trajectories (Matsumoto et al, 2016). Cosmogenic isotopes have the potential to reveal the long-term history of coastal change and to quantify process rates along rocky coastlines (Recorbet et al, 2010;Choi et al, 2012;Regard et al, 2012;Rogers et al, 2012;Hurst et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Numerical models of shore platform evolution have successfully recreated both of these endmember morphologies but have revealed that there are a range of other possible morphologies in between, for example sloping platforms terminating in a scarp (e.g. Trenhaile, 2000;Walkden and Hall, 2005;Matsumoto et al, 2016). Numerical models of platform evolution demonstrate that shore platforms and adjacent sea cliffs tend towards a morphological steady state, Under such conditions the morphology may reflect the combination of RSL change, tides and wave energy availability.…”

Section: Introductionmentioning

confidence: 99%

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Controls on the distribution of cosmogenic <sup>10</sup>Be across shore platforms

2017

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Abstract. Quantifying rates of erosion on cliffed coasts across a range of timescales is vital for understanding the drivers and processes of coastal change and for assessing risks posed by future cliff retreat. Historical records cover at best the last 150 years; cosmogenic isotopes, such as 10 Be could allow us to look further into the past to assess coastal change on millennial timescales. Cosmogenic isotopes accumulate in situ near the Earth surface and have been used extensively to quantify erosion rates, burial dates and surface exposure ages in terrestrial landscapes over the last 3 decades. More recently, applications in rocky coast settings have quantified the timing of mass wasting events, determined long-term averaged rates of cliff retreat and revealed the exposure history of shore platforms. In this contribution, we develop and explore a numerical model for the accumulation of 10 Be on eroding shore platforms. In a series of numerical experiments, we investigated the influence of topographic and water shielding, dynamic platform erosion processes, the presence and variation in beach cover, and heterogeneous distribution of erosion on the distribution of 10 Be across shore platforms. Results demonstrate that, taking into account relative sea level change and tides, the concentration of 10 Be is sensitive to rates of cliff retreat. Factors such as topographic shielding and beach cover act to reduce 10 Be concentrations on the platform and may result in overestimation of cliff retreat rates if not accounted for. The shape of the distribution of 10 Be across a shore platform can potentially reveal whether cliff retreat rates are declining or accelerating through time. Measurement of 10 Be in shore platforms has great potential to allow us to quantify long-term rates of cliff retreat and platform erosion.

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Identifying mechanisms of shore platform erosion using Structure‐from‐Motion (SfM) photogrammetry

Swirad

Rosser

Brain

2019

Earth Surf Processes Landf

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Shore platforms control wave energy transformation which, in turn, controls energy delivery to the cliff toe and nearshore sediment transport. Insight into shore platform erosion rates has conventionally been constrained at millimetre‐scales using micro‐erosion metres, and at metre‐scales using cartographic data. On apparently slowly eroding coasts, such approaches are fundamentally reliant upon long‐term observation to capture emergent erosion patterns. Where in practise timescales are short, and where change is either below the resolution or saturates the mode of measurement, the collection of data that enables the identification of the actual mechanisms of erosion is hindered. We developed a method to monitor shore platform erosion at millimetre resolution within metre‐scale monitoring plots using Structure‐from‐Motion photogrammetry. We conducted monthly surveys at 15 0.25 m2 sites distributed across the Hartle Loup platform in North Yorkshire, UK, over one year. We derived topographic data at 0.001 m resolution, retaining a vertical precision of change detection of 0.001 m. We captured a mean erosion rate of 0.528 mm yr‐1, but this varied considerably both across the platform and through the year. We characterized the volume and shape of eroded material. The detachment volume–frequency and shape distributions suggest that erosion happens primarily via removal of shale platelets. We identify that the at‐a‐point erosion rate can be predicted by the distance from the cliff and the tidal level, whereby erosion rates are higher closer to the cliff and at locations of higher tidal duration. The size of individual detachments is controlled by local micro‐topography and rock structure, whereby larger detachments are observed on more rough sections of the platform. Faster erosion rates and larger detachments occur in summer months, rather than in more energetic winter conditions. These results have the potential to form the basis of improved models of how platforms erode over both short‐ and long‐timescales. © 2019 John Wiley & Sons, Ltd.

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An exploratory numerical model of rocky shore profile evolution

Cited by 45 publications

References 71 publications

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Controls on the distribution of cosmogenic <sup>10</sup>Be across shore platforms

Identifying mechanisms of shore platform erosion using Structure‐from‐Motion (SfM) photogrammetry

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An exploratory numerical model of rocky shore profile evolution

Cited by 45 publications

References 71 publications

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Modelling the relative dominance of wave erosion and weathering processes in shore platform development in micro‐ to mega‐tidal settings

Controls on the distribution of cosmogenic &lt;sup&gt;10&lt;/sup&gt;Be across shore platforms

Identifying mechanisms of shore platform erosion using Structure‐from‐Motion (SfM) photogrammetry

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Controls on the distribution of cosmogenic <sup>10</sup>Be across shore platforms