Wave runup on composite beaches and dynamic cobble berm revetments

Blenkinsopp, Chris; Bayle, Paul M.; Martins, Kévin; Foss, Ollie; Almeida, Luís Pedro; Kaminsky, George M.; Schimmels, Stefan; Matsumoto, Hironori

doi:10.1016/j.coastaleng.2022.104148

Cited by 5 publications

(8 citation statements)

References 48 publications

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“…The MDGS provides a new method to investigate complex beach grain size–slope relationship and related coastal hazards at mixed sediment beaches. For example, better understanding of grain size–slope relationships for mixed sediment beaches are needed to improve estimates of wave runup and coastal flooding (e.g., Blenkinsopp et al, 2022; Fiedler et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

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Development of an automated mobile grain size mapping of a mixed sediment beach

Matsumoto

Young

2023

Earth Surf Processes Landf

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Grain sizes influence beach morphologies, processes, and states (e.g., dissipative, reflective and intermediate), however previous studies analysing beach grain size are often spatially and temporarily sparse. In this study, an automated mobile grain size estimation method using digital photographs (mobile digital grain size, MDGS) was developed and tested at a mixed sediment beach consisting of sand and gravels. The data collection system consisted of a downward‐looking camera, Real Time Kinematic Global Navigation Satellite System, and a camera‐triggering single‐board computer, attached to an all‐terrain vehicle. Digital photographs were collected monthly from January 2021 to March 2022 over a section spanning ~700 m alongshore and processed automatically using an existing (non‐mobile) DGS estimation method. The MDGS results were generally consistent with manually estimated grain sizes (n = 962, r2 = 0.74, RMSE = 5.9 mm) and UAV orthomosaic imagery, although the MDGS sometimes overestimated manually estimated grain sizes particularly for photographs with relatively small sediments. Modelled nearshore waves and subaerial beach survey data from mobile terrestrial LiDAR were used to explore using MDGS in morphological studies. Seasonal grain size trends, observed relationships between nearshore wave height and spatially averaged beach grain size, and the general increasing trends of grain sizes with both beach elevation and local roughness/slope were consistent with previous studies, highlighting the use of MDGS for morpho‐sedimentary mixed sediment beach research. The MDGS provides a unique method to conduct spatially and temporarily high‐resolution mapping of gravel size sediments over large areas (>102 m alongshore). Potential improvements of the MDGS include additional low elevation cameras for improved fine (e.g., sand) grain size estimates, decreased time between photo triggering, and automated removal of erroneous photographs containing surface irregularities (e.g., tire tracks) and non‐sediment features (e.g., seaweed). Overall, the MDGS provides improved surface grain size mapping and investigations of complex grain size–morphology relationships of mixed sediment beaches.

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Section: Discussionmentioning

confidence: 99%

“…For example, better understanding of grain size-slope relationships for mixed sediment beaches are needed to improve estimates of wave runup and coastal flooding (e.g., Blenkinsopp et al, 2022;Fiedler et al, 2020).…”

Section: Seasonal Grain Size Trends and Comparison With Waves And Bea...mentioning

confidence: 99%

Development of an automated mobile grain size mapping of a mixed sediment beach

Matsumoto

Young

2023

Earth Surf Processes Landf

View full text Add to dashboard Cite

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“…'Note that the revetment is a low volume revetment which eectively consists of a few layers of pure cobbles, but it was shown to have a valid coastal protection function (Bayle et al, 2021). Further post-processing of the separated bed/swash elevation data enables the instantaneous shoreline position, which is dened at the most landward point where the swash depth is larger than 0 m, to be tracked in both time and space enabling extraction of the runup and rundown limits (Blenkinsopp et al, 2022b).…”

Section: Separation Of Hydrodynamic and Topographic Measurementsmentioning

confidence: 99%

“…3) A layer of pure sand. The presence of these three layers makes the hydraulic conductivity and water table of a beach with a dynamic revetment or a composite beach dierent from pure gravel beaches, and is expected to inuence the swash dynamics (Holland, 2019;Blenkinsopp et al, 2022b). The swash motions at the wave-by-wave scale cause rearrangement of surface particles, which can in turn lead to temporary exposure and movement of underlying gravel and sand.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, sand beneath the cobbles can be eroded by the water percolating through the permeable pure gravel layer (Bayle et al, 2021); it can also accumulate and compact due to kinetic sieving, which results from the vibratory mechanism of the swash (Wright et al, 1982). In tidal environments, the tide level plays a key role in the dynamics of composite beaches as hydrodynamic conditions change from dissipative at low and mid tide (shoreline on the mildly sloping sand beach face) to reective conditions around high tide, when the swashes interact with the much steeper gravel berm (Blenkinsopp et al, 2022b). These processes were investigated through both a laboratory (Bayle et al, 2020) and eld study (Bayle et al, 2021) and provided physical explanations of the overall dynamics and stability of dynamic revetment and composite beaches.…”

Section: Introductionmentioning

confidence: 99%

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