Spectral Analysis of Beach Cusp Evolution Using 3d Lidar Scans

O’Dea, Annika; Brodie, Katherine L.

doi:10.1142/9789811204487_0058

Cited by 6 publications

(8 citation statements)

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“…Nolan et al [32] reported on the different correlations between the cusp parameters but their data showed a much lower correlation coefficient (Cusp spacing and cusp amplitude: r 2 = 0.23), noting that their dataset covered several sites. O'Dea and Brodie [49] reported on cusp spacing and cusp amplitude as well (r 2 = 0.94), which is higher than the findings in this study. The results presented here demonstrate that the cusp parameters may be strongly related to cusp spacing during or near formation, which is then closely related to the horizontal swash excursion.…”

Section: Cusp Parameterscontrasting

confidence: 89%

Field Observations of a Multilevel Beach Cusp System and Their Swash Zone Dynamics

Nuyts

Hickey

et al. 2021

Geosciences

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This paper presents the observed morphological evolution of a multilevel beach cusp system in Long Strand, Co. Cork, Ireland. The surveys were carried out with an Unmanned Aerial Vehicle (UAV) system between March and September 2019. From this site, three levels of beach cusps on the beachface (i.e., lower beach level, mid beach level and upper beach level), and critical cusp parameters are reported, including cusp spacing, cusp elevation, cusp depth, and cusp amplitude. Thus far, such an extensive dataset has not previously been reported in the literature from a single site. The evolution of the different cusp parameters is then linked with the hydrodynamics in the study area, and new prediction theories are proposed for the different cusp parameters. The Lower beach level cusps (1 < z < 2.5 m Irish Transverse Mercator (ITM)) changed with every tide and appeared when surf-similarity parameter -ξ0 < 1.55. These cusps had a mean cusp spacing of λmean = 11.09 m, which are closely linked with the predictions of the self-organisation theory (p < 0.05). In contrast, the Mid beach level cusps (2.5 < z < 3.5 m ITM) are less dynamic compared to the Lower beach level cusps and can persist between spring tidal cycles. They had a mean cusp spacing of λmean = 18.17 m. The Upper beach level cusps (approximately z = 6 m ITM) are above astronomical tide levels and have a mean cusp spacing of λmean = 40.26 m. They did not change significantly over the survey period due to a lack of major storm events. These findings give a better understanding of the evolution of different cusp parameters for a multilevel beach cusp system and can be used to formulate a global theory regarding their change over time.

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Section: Cusp Parameterscontrasting

confidence: 89%

Field Observations of a Multilevel Beach Cusp System and Their Swash Zone Dynamics

Nuyts

Hickey

et al. 2021

Geosciences

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“…Of these, those with long-shore wavelengths (spacing) up to ∼ 50 m are usually considered to be formed under swash-dominant processes. Numerous field studies have repeatedly shown that beach cusps generally form during calm, narrow-banded, shore-normal wave conditions which promote accretion (Holland, 1998;Almar et al, 2008;Vousdoukas, 2012;O'Dea and Brodie, 2019). Cusps also form (less frequently) under energetic or erosive conditions, and their morphological development is often dynamic, featuring long-shore migration in which new cusp fields are generated over pre-existing formations (Masselink et al, 1997;Masselink and Pattiaratchi, 1998b;van Gaalen et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Cusps are often thought to develop via two primary mechanisms: 1) wave height patterns caused by edge waves in the long-shore dimension (Inman and Guza, 1982), or 2) from self-organisation which allows small bathymetric perturbations to grow through positive morphodynamic feedback mechanisms (Werner and Fink, 1993;Coco et al, 1999). Whether or not edge waves, self organisation, or a combination of both theories are responsible for beach cusp formation remains an open question (Holland and Holman, 1996;O'Dea and Brodie, 2019). Recent numerical simulations of nearshore flow patterns suggest that wave reflection over steep beaches can also be a mechanism for beach cusp formation (Almar et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Morphodynamic modelling of beach cusp formation: The role of wave forcing and sediment composition

et al. 2021

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A field of beach cusps formed during a field experiment at Nha Trang Beach, Vietnam, under accretive conditions. The measured data was used to set-up morphodynamic simulations in XBeach, which was able to simulate cusp formation from an initially long-shore uniform beach profile. Several types of simulations were run in order to observe the resulting variation in mean cusp dimensions (length, depth and height), swash flow patterns, and sediment sorting. Both time-constant (JONSWAP) and time-varying (measured) wave forcing conditions were superimposed on the measured tide. In the former, four wave parameters were varied (wave height, period, direction, and spreading), while in the latter, the median sediment size and sediment composition were varied. The wave period was found to primarily influence long-shore length scales, the wave height cross-shore length scales, and obliquely incident waves enhance all these dimensions particularly under narrow-banded conditions. Cusps are not prominent if the wave energy is too low to effect

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“…Recent developments with continuous laser scanning [2,27,28] have provided the opportunity to study the intertidal area topography [8,[29][30][31] with accurate high temporal-spatial measurements.…”

Section: Introductionmentioning

confidence: 99%

Cross-Shore Intertidal Bar Behavior along the Dutch Coast: Laser Measurements and Conceptual Model

Vos

Spaans²,

Reniers

et al. 2020

JMSE

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Intertidal bars are naturally occurring morphological features along the waterline of sandy beaches. Present quantitative knowledge on intertidal bar behavior is limited, due to the scarcity of data resources and the limitations of traditional survey techniques. To investigate and quantify the cross-shore morphologic behavior of intertidal bars, hourly terrestrial laser scans of Kijkduin beach (The Netherlands) are used and a conceptual evolution intertidal bar model is constructed. In a six-week period in January and February 2017, a pronounced intertidal bar formed at Kijkduin beach and migrated onshore during mild wave conditions and eroded again during storm conditions. The observed maximum shoreward migration was 30 m horizontally with a maximum growth of about 1 m in the vertical direction. Onshore sediment transport fluxes peaked around 2 m3 per m width per day. In the conceptual model proposed here, run-up and overwash processes are dominant for shoreward growth and migration of the bar and submersion processes are responsible for bar destruction.

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Spectral Analysis of Beach Cusp Evolution Using 3d Lidar Scans

Cited by 6 publications

References 0 publications

Field Observations of a Multilevel Beach Cusp System and Their Swash Zone Dynamics

Field Observations of a Multilevel Beach Cusp System and Their Swash Zone Dynamics

Morphodynamic modelling of beach cusp formation: The role of wave forcing and sediment composition

Cross-Shore Intertidal Bar Behavior along the Dutch Coast: Laser Measurements and Conceptual Model

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