Emergent coastal behaviour results in extreme dune erosion decoupled from hydrodynamic forcing

Hird, Simon; Stokes, Christopher; Masselink, Gerd

doi:10.1016/j.margeo.2021.106667

Cited by 10 publications

(6 citation statements)

References 49 publications

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“…For a number of decades, the river channel was artificially pinned against the northern headland by a small rock training wall (Figure 2, middle panel) to maintain a navigation channel across the beach for boats. However, following significant redistribution of the beach sediment during the unprecedented storms of the 2013/14 winter (Hird et al, 2021;Masselink et al, 2016), the river channel avulsed and now meanders laterally across the beach towards the south before discharging seaward through a channel that migrates between the south and north of the bay.…”

Section: Study Sitementioning

confidence: 99%

New insights into combined surfzone and estuarine bathing hazards

Stokes,

Poate,

Masselink

et al. 2024

Preprint

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Abstract. Rip currents are the single largest cause of beach safety incidents globally, but where an estuary mouth intersects a beach, additional flows are created that can exceed the speed of a typical rip current, significantly increasing the hazard level for bathers. However, there is a paucity of observations of surfzone currents at estuary mouth beaches, and our understanding and ability to predict how the bathing hazard varies under different wave and tide conditions is therefore limited. Using field observations and process-based XBeach modelling, we demonstrate how surfzone currents can be driven by combinations of estuary discharge and wave-driven rip currents under various combinations of wave and tide forcing. While previous studies have demonstrated the high hazard that rip currents pose, typically during lower stages of the tide, here we demonstrate that an estuary mouth beach can exhibit flows reaching 1.5 m/s – up to 50 % stronger than typical rip current flows – with a high proportion (>60 %) of simulated bathers exiting the surfzone during the upper half of the tidal cycle. The three dimensional ebb shoal delta was found to strongly control surfzone currents by providing a conduit for estuary flows and acting as a nearshore bar system to generate wave-driven ‘river channel rips’. Despite significant spatiotemporal variability in the position of the river channels on the beach face, it was found to be possible to hindcast the timing and severity of past bathing incidents from model simulations, providing a means to forewarn bathers of hazardous flows.

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Section: Study Sitementioning

confidence: 99%

New insights into combined surfzone and estuarine bathing hazards

Stokes,

Poate,

Masselink

et al. 2024

Preprint

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“…The method used to display the changes in elevation was DEMs of difference (DoD) (Williams, 2012). DoDs are calculated by subtracting one DEM from another in order to calculate the amount of elevation change per pixel (Pollard et al, 2019;Hird et al, 2021). These DEMs must be the same horizontal and vertical resolutions, whereby a pixel in one DEM must represent the same spatial extent as a pixel in the same position in another DEM.…”

Section: Data Preparationmentioning

confidence: 99%

Spatial-temporal variability: characterisation of a beach system using high resolution radar data

Murphy

Plater

Bird³

et al. 2023

Front. Mar. Sci.

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Intertidal areas experience a series of complex dynamic processes that affect beach morphology. Many of these processes are difficult to monitor, particularly due to the limited availability of high-resolution data. This study utilises high resolution radar-derived DEMs obtained through the temporal waterline method high resolution to perform a spatio-temporal analysis of beach morphology over the macrotidal nearshore of Rossall Beach, UK. Beach elevation changes are characterized, providing new insights into the morphological processes from fortnightly to seasonal time scales. The results of this analysis draw focus to the short-term variations in beach morphology and their contributions to long-term change. Observation of spatio-temporal variation displayed an intertidal system in a seasonal steady state equilibrium, somewhat dominated by elevation changes within the spring and summer months. Furthermore, the upper-intertidal zone displays evidence of continuing accretion. Though the analysis within this study is mostly explorative, it shows the potential of radar data for autonomous monitoring and spatio-temporal characterization of the coast. This enables coastal managers and stakeholders to build a long-term picture of the coastline, reducing vulnerability to coastal hazards and building resilience.

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“…Temporal morphological changes on beaches are complex and occur as a result of seasonal or longer-term variations in hydrodynamics or sediment supply (Anfuso et al, 2016) and episodic events such as storms (Loureiro et al, 2009) after which recovery can last for years or even decades (Orford et al, 1999). Beach behaviour can also be decoupled from hydrodynamic forcing and is then characterised by "emergent behaviour" (Hird et al, 2021). There are also feedbacks between beach morphology and dynamics (Sénéchal et al, 2009, Anthony, 2012.…”

Section: Natural Sandy Beaches and Sea-level Risementioning

confidence: 99%

Response of natural, modified and artificial sandy beaches to sea-level rise

Cooper

2022

CIG

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Sandy beaches occur in a wide variety of environmental settings and as components of a diverse range of coastal system types. These variations among beaches lead to significant differences in their mesoscale (multi-decadal, km length scale) behaviour, including their response to sea-level rise. In addition to this natural variability, the degree to which the sandy beach system has been or will be modified by humans is a major influence on how it responds to sea-level change. From a spectrum of beach types based on the degree of human modification, three situations (Natural, Modified and Artificial beaches) are considered in order to demonstrate the role of humans as geomorphic agents as sandy beaches respond to rising sea level. The potential trajectories of change are assessed, and future scenarios are presented and discussed. Natural beaches are most likely to survive sea-level rise, while the fate of artificial beaches depends almost entirely on the politics and economics of what lies immediately landward. In all categories of beach, human decision-making is the most important determinant of sandy beach response to sea-level rise.

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Emergent coastal behaviour results in extreme dune erosion decoupled from hydrodynamic forcing

Cited by 10 publications

References 49 publications

New insights into combined surfzone and estuarine bathing hazards

New insights into combined surfzone and estuarine bathing hazards

Spatial-temporal variability: characterisation of a beach system using high resolution radar data

Response of natural, modified and artificial sandy beaches to sea-level rise

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