Alongshore Variability in Coastal Dune Erosion and Post-Storm Recovery, Northern Coast of France

Héquette, Arnaud; Ruz, Marie‐Hélène; Zemmour, Amar; Marin, Denis; Cartier, Adrien; Sipka, Vincent

doi:10.2112/si88-004.1

Cited by 35 publications

(22 citation statements)

References 87 publications

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“…Two factors were considered to explain this variation: the role of intertidal bar migration in onshore sediment supply and the longshore variation in nearshore hydrodynamic parameters. Compared to regional scale studies that found variation in water level more important than wave height in determining longshore variation in dune erosion [20,32], over the smaller scale of this site, water level variation was not found to match areas of erosion. Statistically significant longshore variation in significant wave height was observed with larger significant wave heights fronting areas of erosion.…”

Section: Discussioncontrasting

confidence: 95%

“…Relationships between dune volume or dune volume change and upper intertidal beach volume or width were not found, suggesting it is less important at Crymlyn Burrows. This is in contrast to studies ranging from embayment [29] to regional scales [20,32]. It is postulated that the difference may be related to the lack of supra-tidal beach between the HAT level and the dunefoot at the studied site; lack of supratidal beach means that wave coincident with spring high tide will impact the dunefoot all along the studied dune system.…”

Section: Discussioncontrasting

confidence: 65%

“…Waves are typically considered from an erosive perspective in relation to dune systems e.g., [19][20][21][22][23][24][25]; however, there is a recognition that wave-driven onshore transport can provide sediment reservoirs that subsequently can nourish dunes through aeolian transport [26][27][28]. Spatial variation in foredune evolution has been noted over a range of scales [29][30][31][32]. Understanding the driving factors for this variation is important to facilitate appropriate management.…”

Section: Introductionmentioning

confidence: 99%

“…Understanding the driving factors for this variation is important to facilitate appropriate management. Over regional scales in Northern France, Héquette, et al [32] find that surge elevation is more important than wave height in describing spatial variation in dune erosion and also note the importance of upper intertidal beach width. Over the 3.6 km Narrabeen embayment (Australia), Splinter, et al [29] find dune erosion is best related to pre-storm dune toe elevation.…”

Section: Introductionmentioning

confidence: 99%

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Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

et al. 2020

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Coastal dunes have global importance as ecological habitats, recreational areas, and vital natural coastal protection. Dunes evolve due to variations in the supply and removal of sediment via both wind and waves, and on stabilization through vegetation colonization and growth. One aspect of dune evolution that is poorly understood is the longshore variation in dune response to morphodynamic forcing, which can occur over small spatial scales. In this paper, a fixed wing unmanned aerial vehicle (UAV), is used to measure the longshore variation in evolution of a dune system in a megatidal environment. Dune sections to the east and west of the study site are prograding whereas the central portion is static or eroding. The measured variation in dune response is compared to mesoscale intertidal bar migration and short-term measurements of longshore variation in wave characteristics during two storms. Intertidal sand bar migration is measured using satellite imagery: crescentic intertidal bars are present in front of the accreting portion of the beach to the west and migrate onshore at a rate of 0.1–0.2 m/day; episodically the eastern end of the bar detaches from the main bar and migrates eastward to attach near the eastern end of the study area; bypassing the central eroding section. Statistically significant longshore variation in intertidal wave heights were measured using beachface mounted pressure transducers: the largest significant wave heights are found in front of the dune section suffering erosion. Spectral differences were noted with more narrow-banded spectra in this area but differences are not statistically significant. These observations demonstrate the importance of three-dimensionality in intertidal beach morphology on longshore variation in dune evolution; both through longshore variation in onshore sediment supply and through causing longshore variation in near-dune significant wave heights.

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Section: Discussioncontrasting

confidence: 95%

Section: Discussioncontrasting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

et al. 2020

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“…An intense storm in 1932 caused foredune destruction and a 300-600-m inland migration of transgressive dunes in east Canada, and the recovery took about four decades (Mathew et al, 2010). Similarly, storms caused coastal dune erosion in southern USA as well as in northern France, and poststorm recovery took about 10 years (Héquette et al, 2019;Houser et al, 2015). Dune stabilisation on Fraser Island in Australia was coincident with increased cyclone frequency and intensity (Levin, 2011).…”

Section: Changes In Climatementioning

confidence: 99%

Coastal dune mobility over the past century: A global review

Gao

Kennedy

Konlechner

2020

Progress in Physical Geography: Earth and Environment

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The mobility of coastal dunes is characterised by bio-geomorphological responses related to change in boundary conditions, particularly sediment supply, wind and vegetation cover, as well as human activities. There remains uncertainty regarding the relative importance of these drivers on dune mobility at a global scale. In this study, trends and dominant drivers of coastal dune mobility are synthesised through the literature review focusing on shifts in dune mobility over the last century (1870–2018). In total, 176 individual dunes, with 55 dunes from the Europe-Mediterranean area, 23 from Africa, 30 from North America, 23 from South America, 20 from Oceania and 23 from Asia, are reviewed in this work. The results show that there is a worldwide trend of dune stabilisation, with 93% (164 out of 176) of the reviewed sites showing a loss of bare sand area due to an increase in vegetation cover and urbanisation expansion. Multiple factors have contributed to the stabilisation process, including (a) land-use change such as the change of traditional farming practises, coastal urbanisation and tourism development; (b) dune stabilisation projects; (c) sediment decline caused by the riverine and coastal constructions; and (d) change in climate (i.e. the decrease in windiness, and the increase in temperature and rainfall) and storms. Our results suggest human intervention played a dominant role in altering dune mobility for most dunes during the past century, while climate and storms are also important drivers, especially for dune sites with limited human activities.

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Biotic and abiotic factors governing dune response to storm events

Garzon

Ferreira

2021

Earth Surf Processes Landf

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The alongshore response of dunes to storm events can be extremely variable and, consequently, their capacity to maintain their services, including the protection of hinterland communities. In this study, the role of biotic and abiotic factors determining the magnitude of dune retreat driven by a severe storm along a 60 km barrier island system was investigated. Data from high-resolution satellite imagery, digital terrain models, and wave propagation models were used in this assessment. The assessed abiotic factors included the backshore volume, dune height, downdrift inlet distance, and incident wave power. The evaluated biotic factor was the vegetation cover, characterized by a vegetation index retrieved from the multispectral imagery.The results revealed large alongshore variability on dune retreat, ranging from negligible impact to ca. 40 m of retreat. All combined factors allowed us to explain up to 70% of the dune retreat variability through a multi-regression analysis. Among all investigated factors, the major contributor controlling the magnitude of dune retreat was the backshore volume (more robust berms reduced the retreat) followed by the wave power (normal and longitudinal components). Moreover, the removal of local salient features in the dune line caused the straightening of the coastline, highly contributing to the development of dune retreat hotspots. The other evaluated factors had a smaller influence on reducing coastal retreat, including the vegetation, whose contribution to dune protection was around one order of magnitude lower than that provided by the backshore volume. The results highlight the importance of regional assessments to understand the causes behind the large alongshore variability of storm impacts at dunes. They also state the relatively low influence of the vegetation from this climatic region to enhance dune resistance to storms.

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Alongshore Variability in Coastal Dune Erosion and Post-Storm Recovery, Northern Coast of France

Cited by 35 publications

References 87 publications

Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

Coastal dune mobility over the past century: A global review

Biotic and abiotic factors governing dune response to storm events

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