Understanding spatio-temporal barrier dynamics through the use of multiple shoreline proxies

Pollard, John; Spencer, T.; Brooks, Susan; Christie, Elizabeth; Möller, Iris

doi:10.1016/j.geomorph.2020.107058

Cited by 13 publications

(15 citation statements)

References 78 publications

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“…Furthermore, Orford and Anthony (2011) observed that long-term (multi-annual to centennial) gravel barrier change is principally controlled by extreme events, sediment supply and sea level rise rate but that sediment supply can be discounted 'under conditions of limited longshore sediment supply (essentially swash-aligned, single beachridge barrier systems)' (Orford and Anthony, 2011, 43). Evidence of the BPBS displaying swash-aligned behaviour is provided by Pollard et al (2020) whose historical shoreline change analysis of the BPBS showed that the classic drift-aligned signal of downdrift westward barrier extension (evident from 1886 to 2016) was replaced in the period 1981-2016 by a shift towards a more swash-aligned system, characterised by no clear alongshore variation in the rate of shoreline change (see Fig. 3, (Pollard et al, 2020)).…”

Section: Numerical Model Chain Set-upmentioning

confidence: 99%

“…Evidence of the BPBS displaying swash-aligned behaviour is provided by Pollard et al (2020) whose historical shoreline change analysis of the BPBS showed that the classic drift-aligned signal of downdrift westward barrier extension (evident from 1886 to 2016) was replaced in the period 1981-2016 by a shift towards a more swash-aligned system, characterised by no clear alongshore variation in the rate of shoreline change (see Fig. 3, (Pollard et al, 2020)). We conclude, therefore, that our focus on cross-shore profile change is justified in the context of the contemporary behaviour of this barrier system.…”

Section: Numerical Model Chain Set-upmentioning

confidence: 99%

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Gravel barrier resilience to future sea level rise and storms

et al. 2022

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Globally, communities, ecosystems, and assets situated within the coastal zone will likely experience increased risk in the future owing to chronic and acute pressures associated with climate change and accompanying sea level rise. Gravel barrier islands represent an intermediate pathway between seaward hazards and vulnerable landward receptors and possess inherent morpho-sedimentary characteristics which allow coastal risk reduction functions. If gravel barriers are to be usefully and reliably integrated into broader coastal risk management strategies, there is a need to understand the extent to which these landforms are likely to remain resilient under future environmental conditions. Using the Blakeney Point Barrier System, southern North Sea, this study investigates the resilience of gravel barrier landforms to storm surge conditions under future sea level rise scenarios. Resilience is assessed through reference to barrier resistance, susceptibility to state change, persistence, and continued functional performance. Numerical modelling reveals that variable pre-surge barrier morphologies result in a spectrum of episodic resilience trajectories along the barrier frontage. This study also considers the role of humans in altering landscape resilience, demonstrating that previously managed barrier sections (through reprofiling to steepen and heighten the barrier) are more vulnerable to severe morphological change, and associated landward overtopping volume, compared to unmanaged barrier sections. This said, under moderate to high sea level rise, even unmanaged barrier sections failed to demonstrate resilience to storm surge forcing. Such insights help temper our expectations regarding the coastal erosion and flood risk reduction functions of gravel barriers in the face of global environmental change.

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Section: Numerical Model Chain Set-upmentioning

confidence: 99%

Section: Numerical Model Chain Set-upmentioning

confidence: 99%

Gravel barrier resilience to future sea level rise and storms

et al. 2022

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“…At several sites, this management becomes unsustainable into the future, raising the question as to what might happen if sediment management ceases and natural processes can return unchecked to these frontages. In the 1980s and 90s, a number of publications were dedicated to the natural ontogeny and in particular roll-back of coarse clastic barrier beaches focussing on barriers in Ireland [10][11][12] and Canada [13][14][15] followed from 2000 by publications on barriers like Hurst Spit [16], Porlock [17,18], Cley [19][20][21] and Sillon de Talbert [22][23][24], where previous management including sediment movement had ceased or hard structures been removed, or where new management was going to be introduced [16].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, sites with higher spatio-temporal survey resolution have become available [21,43] and the present study is an extension of this early work at Medmerry. As such the paper addresses the following questions:…”

Section: Introductionmentioning

confidence: 99%

Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach

Dornbusch¹

2021

JMSE

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Sea level rise increases the pressure on many coastlines to retreat landwards which will lead to coastlines previously held in position through management, being allowed to retreat where this is no longer affordable or sustainable. Barrier beaches have historically rolled back in response to different hydrodynamic events and sea level rise, but very little is known as to how quickly and how far roll-back is going to occur once management has ceased. Data from more than 40 topographical surveys collected over 7 years along the 1.5 km long, almost swash-aligned shingle barrier at Medmerry (southern England) are used together with hydrodynamic data in a wide-ranging assessment of barrier roll-back. This study shows that roll-back is progressing through time along the barrier in downdrift direction in response to a gradual reduction in cross-sectional area through longshore transport. The Barrier Inertia concept provides a practical means to assess stability/instability for events experienced, but also a tool to assess the short- to medium term risk to the coast downdrift of the immediate study area where flood risk still needs to be managed. Roll-back is influenced particularly by the creation of an artificial tidal breach and removal of its sediment, the elevation of the underlying marsh and clay sediments, the number and severity of storms experienced and the presence of legacy groynes; roll-back has exceeded modelled predictions and expert judgement by an order of magnitude.

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“…Further work by Plomaritis et al [17] developed this classification into a regional scale assessment of storm related overwash and barrier breaching using a numerical model of coastal overwash [18], allowing the formulation of overwash volumes without the need for numerical modeling which is computationally expensive over larger spatial scales. Recent literature has begun to study mixed sand-gravel beaches under different tectonic settings [19], and where gradients in both alongshore and cross-shore sediment transport play a role in governing the sediment transport regime [20][21][22].…”

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confidence: 99%

Modeling Impact of Intertidal Foreshore Evolution on Gravel Barrier Erosion and Wave Runup with XBeach-X

Phillips

Brown

Plater

2020

JMSE

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This paper provides a sensitivity analysis around how characterizing sandy, intertidal foreshore evolution in XBeach-X impacts on wave runup and morphological change of a vulnerable, composite gravel beach. The study is motivated by a need for confidence in storm-impact modeling outputs to inform coastal management policy for composite beaches worldwide. First, the model is run with the sandy settings applied to capture changes in the intertidal foreshore, with the gravel barrier assigned as a non-erodible surface. Model runs were then repeated with the gravel settings applied to obtain wave runup and erosion of the barrier crest, updating the intertidal foreshore from the previous model outputs every 5, 10 and 15 min, and comparing this with a temporally static foreshore. Results show that the scenario with no foreshore evolution led to the highest wave runup and barrier erosion. The applied foreshore evolution setting update is shown to be a large control on the distribution of freeboard values indicative of overwash hazard and barrier erosion by causing an increase (with 5 min foreshore updates applied) or a decrease (with no applied foreshore updating) in the Iribarren number. Therefore, the sandy, intertidal component should not be neglected in gravel barrier modeling applications given the risk of over- or under-predicting the wave runup and barrier erosion.

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Understanding spatio-temporal barrier dynamics through the use of multiple shoreline proxies

Cited by 13 publications

References 78 publications

Gravel barrier resilience to future sea level rise and storms

Gravel barrier resilience to future sea level rise and storms

Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach

Modeling Impact of Intertidal Foreshore Evolution on Gravel Barrier Erosion and Wave Runup with XBeach-X

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