Coastal Catch-up Following Defence Removal at Happisburgh

Walkden, Mike; Watson, Gary; Johnson, Alice; Heron, Eleanor; Tarrant, Owen

doi:10.1680/cm.61149.523

Cited by 7 publications

(19 citation statements)

References 5 publications

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“…This led, very rapidly, to the formation of an embayment, partially stabilized at its northern end by a series of placements of a rock armour revetment. The EA [3] report that, following structure failure, up to 140 m (7 m/yr) of recession occurred within the Happisburgh embayment between 1992 and 2012. Figure 1.…”

Section: Study Sitementioning

confidence: 99%

“…A plausible explanation (or hypothesis) for post-removal increase in erosion rate is that the discontinuity in the platform lowering rates across the line of the defence drives the rapid erosion after this defence is lost [3]. Figure 1 illustrates the stages through which these processes may occur.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 illustrates the stages through which these processes may occur. Sensitivity testing [3] suggests that the beach thickness is a key factor in determining the scale of response, and whether there is a net gain or loss of land when more natural conditions have re-established. A reduction in beach volume following defence construction leads to a thinning of the beach, and so an increase in wave-driven platform downwearing and the accelerated development of a step.…”

Section: Introductionmentioning

confidence: 99%

“…This would have important implications for coastal management including: (1) new defences may be seen as detrimental because of the decommissioning losses (so long as those are accounted for) but conversely (2) decisions to maintain existing defences may become more likely, because of the increased losses that would result from their decommissioning. The analysis presented by [3] is lacking any data of beach thickness and contains little direct evidence of accelerated platform lowering. Platform lowering is difficult to observe at the study site (and in many places) during storms due to the harsh conditions and, during calm weather, because contemporary beach deposits lie on top of the shore platform.…”

Section: Introductionmentioning

confidence: 99%

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A Quantitative Assessment of the Annual Contribution of Platform Downwearing to Beach Sediment Budget: Happisburgh, England, UK

Payo

Walkden²,

Ellis

et al. 2018

JMSE

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Field and numerical investigations at Happisburgh, East coast of England, UK, sought to characterize beach thickness and determine geologic framework controls on coastal change. After a major failure of coastal protection infrastructure, removal of about 1 km of coastal defence along the otherwise protected cliffed coastline of Happisburgh triggered a period of rapid erosion over 20 years of ca. 140 m. Previous sensitivity studies suggest that beach thickness plays a major role in coastal recession. These studies were limited, however, by a lack of beach volume data. In this study, we have integrated the insights gained from our understanding of the Quaternary geology of the area, a novel non-intrusive passive seismic survey method, and a 3D novel representation of the subsurface source and transportable material into a coastal modelling environment to explore the role of beach thickness on the back wearing and downwearing of the cliffs and consolidated platform, respectively. Results show that beach thickness is non-homogeneous along the study site: we estimate that the contribution to near-shore sediment budget via platform downwearing is of a similar order of magnitude as sediment lost from the beach and therefore non-negligible. We have provided a range of evidence to support the idea that the Happisburgh beach is a relatively thin layer perched on a sediment rich platform of sand and gravel. This conceptualization differs from previous publications, which assume that the platform was mostly till and fine material. This has direct implication on regional sediment management along this coastline. The present study contributes to our understanding of a poorly known aspect of coastal sediment budgeting and outlines a quantitative approach that allows for simple integration of geological understanding for coastline evolution assessments worldwide.

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Section: Study Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Quantitative Assessment of the Annual Contribution of Platform Downwearing to Beach Sediment Budget: Happisburgh, England, UK

Payo

Walkden²,

Ellis

et al. 2018

JMSE

Self Cite

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“…Some progress has been made in recent years using the SCAPE numerical modelling tool (e.g. Walkden et al, 2015). That study demonstrated coastal response that included retreat beyond the position the shore would have been expected to reach in the absence of coast protection (i.e.…”

Section: Introductionmentioning

confidence: 91%

Modelling Rapid Coastal Catch-Up After Defence Removal Along the Soft Cliff Coast of Happisburgh, Uk

Payo¹,

Walkden²

2018

Int. Conf. Coastal. Eng.

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There are currently no well-established methods of predicting coastal catch-up, i.e. the response of shores to the removal of existing coast protection. Such estimates are vital to inform decisions around the renewal of such structures. At a deeper level, the lack of predictive methods undermines progress towards more sustainable approaches to coastal management, and the implementation of policies of managed realignment. Some progress has been made in recent years using the SCAPE numerical modelling tool (e.g. Walkden et al, 2015). That study demonstrated coastal response that included retreat beyond the position the shore would have been expected to reach in the absence of coast protection (i.e. coast protection apparently causing a net loss of land). That study raised important questions, but was limited in the respect that it represented the coast in two-dimensions (i.e. without alongshore interactions). In this work we illustrate how the novel Coastal Modelling Environment (CoastalME, Payo et al. 2017) is able to reproduce coastal catch-up at Happisburgh at the East coast of UK, and to do so with more physical realism than was possible with the SCAPE model, including accounting for alongshore variations).

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Nine months of daily LiDAR, orthophotos and MetOcean data from the eroding soft cliff coast at Happisburgh, UK

Pennington,

Shaw,

Brooks

et al. 2024

Sci Data

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The dynamic interaction between cliff, beach and shore-platform is key to assessing the sediment balance for coastal erosion risk assessments, but this is poorly understood. We present a dataset containing daily, 3D,colour LiDAR scans of a 450 m coastal section at Happisburgh, Norfolk, UK. This previously para-glaciated region comprises mixed sand-gravel sediments, which are less well-understood and well-studied than sandy beaches. From Apr-Dec 2019, 236 daily surveys were carried out. The dataset presented includes: survey areas, transects LiDAR scans, georeferenced orthophotos, meteorological- and oceanographical conditions during the Apr-Dec observation period. Full LiDAR point-clouds are available for 67 scans (Oct-Dec). Hourly time-series of offshore sea-state parameters (significant wave height, mean propagation direction, selected spectral periods) were obtained by downscaling the ERA5 global reanalysis data (global atmosphere, land surface and ocean waves) using the numerical model Simulating Waves Nearshore (SWAN). We indicate how to obtain hourly precipitation time-series by interpolating ERA5 data. This dataset is important for researchers understanding the interaction between cliff, beach and shore-platform in open-coast mixed-sand-gravel environments.

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Coastal Catch-up Following Defence Removal at Happisburgh

Cited by 7 publications

References 5 publications

A Quantitative Assessment of the Annual Contribution of Platform Downwearing to Beach Sediment Budget: Happisburgh, England, UK

A Quantitative Assessment of the Annual Contribution of Platform Downwearing to Beach Sediment Budget: Happisburgh, England, UK

Modelling Rapid Coastal Catch-Up After Defence Removal Along the Soft Cliff Coast of Happisburgh, Uk

Nine months of daily LiDAR, orthophotos and MetOcean data from the eroding soft cliff coast at Happisburgh, UK

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