Regional versus local wind speed and direction at a narrow beach with a high and steep foredune

Winter, Winnie de; Donker, Jasper; Sterk, G.; Beem, Job van; Ruessink, Gerben

doi:10.1371/journal.pone.0226983

Cited by 15 publications

(33 citation statements)

References 41 publications

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“…The amount of sand that reaches the dune foot (implementing the cosine effect) is 3.7 × 10 4 kg/m and 2.7 × 10 4 kg/m for q p and q a , respectively. This amount is larger than observed (see also [13]), as the dune volume at this site increases with 2.3 × 10 4 kg/m/year during accretion periods [57]. An interesting future step is to calculate aeolian transport rates in supply-limited conditions, like the AeoLis model developed by [58].…”

Section: Relevance Of Days With Limited Transportmentioning

confidence: 81%

“…Refs. [13,51] illustrated with detailed wind measurements at the study site that the regional (IJmuiden) wind speed generally overestimates local wind speed, especially when the wind is blowing onshore. Here, we adapt the wind direction (θ) dependent correction factors proposed by [51] to translate regional into local wind speeds and use these local wind speeds to calculate the critical fetch and the potential transport.…”

Section: Model Set-upmentioning

confidence: 94%

“…Time-averaged aeolian transport models often use only grain size and wind shear velocity [1][2][3][4]. This provides good results under controlled conditions, with a dry, horizontal surface, uniform grain size and steady wind, but transport on a natural beach is also affected by, for example, the moisture content of the sand, the beach slope, the bed roughness, and wind deflection by the foredune (e.g., [2,3,[5][6][7][8][9][10][11][12][13]). The computed volume of wind-blown sand often exceeds the volume deposited on the foredune, with the latest reaching values as small as 15% of the former when the beach is narrow [2,[10][11][12]14,15].…”

Section: Introductionmentioning

confidence: 99%

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Using Video Monitoring to Test a Fetch-Based Aeolian Sand Transport Model

Hage

Ruessink

Aartrijk

et al. 2020

JMSE

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Transport of beach sand to the foredune by wind is essential for dunes to grow. The aeolian sand transport rate is related to wind velocity, but wind-based models often overpredict this transport for narrow beaches (<100 m). To better predict aeolian sand transport, the fetch-based Aeolus model was developed. Here, we qualitatively test this model by comparing its transport-rate output to visual signs of aeolian transport on video imagery collected at Egmond aan Zee, the Netherlands, during a six-month winter period. The Aeolus model and the Argus images often agree on the timing of aeolian transport days, except when transport is small; that is not always visible on the Argus images. Consistent with the imagery (minimal signs of aeolian activity in strong winds), the Aeolus model sometimes predicts the actual transport to be smaller than the potential transport. This difference is largest when wind velocity is large, and its direction is cross-shore. Although transport limitations are not predicted to be common, the results suggest that their effect on the total transport in the study period was substantial. This indicates that the fetch distance should be taken into account when calculating aeolian transport for narrow beaches on longer timescales (>weeks).

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Section: Relevance Of Days With Limited Transportmentioning

confidence: 81%

Section: Model Set-upmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Using Video Monitoring to Test a Fetch-Based Aeolian Sand Transport Model

Hage

Ruessink

Aartrijk

et al. 2020

JMSE

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“…However, this study used regional wind data, and according to a field campaign at the study site in 2017, the local wind (i.e., on the beach) is often weaker than the regional one because of the presence of the high foredune with a steep seaward side. Ruessink et al (2018b) and de Winter et al (2020) illustrated with detailed wind measurements at the study site that the regional (IJmuiden) wind speed generally overestimates local wind speed, especially when the wind is blowing onshore. Here, we adapt the wind direction (θ) dependent correction factors proposed by Ruessink et al (2018b) to translate regional into local wind speeds and use these local wind speeds to calculate the critical fetch and the potential transport.…”

Section: Model Set-upmentioning

confidence: 95%

“…Time-averaged aeolian transport models often use only grain size and wind shear velocity (Hsu, 1974;Davidson-Arnott and Law, 1996;Bauer and Davidson-Arnott, 2002;Sherman et al, 2013a). This provides good results under controlled conditions, with a dry, horizontal surface, uniform grain size and steady wind, but transport on a natural beach is also affected by, for example, the moisture content of the sand, the beach slope, the bed roughness, and wind deflection by the foredune (e.g., Delgado-Fernandez and Davidson-Arnott, 2011;Edwards and Namikas, 2009;Wiggs et al, 2004;Nield et al, 2013;Nield et al, 2014;Bauer and Davidson-Arnott, 2002;Svasek and Terwindt, 1974;Davidson-Arnott and Law, 1996;Jackson and Nordstrom, 1998;Sherman et al, 1998;de Winter et al, 2020). The computed volume of wind-blown sand often exceeds the volume deposited on the foredune, with the latest reaching values as small as 15% of the former when the beach is narrow (Svasek and Terwindt, 1974;Bauer et al, 1996;Davidson-Arnott and Law, 1996;Jackson and Nordstrom, 1998;Sherman et al, 1998;Bauer et al, 2009).…”

Section: Chapter 4 41 Introductionmentioning

confidence: 99%

Long-term video monitoring of aeolian activity on a narrow beach

Hage¹

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Aeolian sand transport takes place when the wind is strong enough to lift a grain of sand. Predicting aeolian transport for beaches is difficult, as existing predictive models, which usually only have the wind velocity as a variable, are designed for ideal circumstances with a steady wind flow, a homogeneous grain size, and a dry and flat sand surface. Sandy beaches show different conditions. When wind-only models are applied, the resulting amount of sand that is predicted to be deposited on the foredune often exceeds the measured amount considerably, especially when the beach is less than several tens of metres wide. This is caused by transport limiting factors, such as surface moisture, the formation of salt or algae crusts, the presence of vegetation, or snow and ice cover. The aeolian transport rate increases downwind until it reaches its maximum at a distance termed the critical fetch length. When the available distance, or maximum fetch, cannot reach this critical fetch, aeolian transport will not reach its potential value. This is particularly relevant for narrow beaches. As a consequence, the moment of largest potential transport does not necessarily coincide with the moment of largest actual transport. When the actual transport is smaller than expected, the transport is limited. When this is not the case, the transport is unlimited. When transport events are limited and unlimited, and what factors control this, is not well understood. Accordingly, we also have limited capabilities in accurately predicting the long-term (>months) amount of wind-blown sand to the foredune. Improved understanding of long-term aeolian sand transport is important as the sand contributes to dune growth and recovery from storms, which is a relatively slow process and takes months to years (long-term). In contrast, erosive storm events last only a few hours or days. Coastal dunes have been strengthened and encouraged to grow to protect densely populated hinterlands by planting marram grass or placing fences to catch the sand and keep it in place. This, however, has created an unnaturally high foredune that prevents sand from being transported further inland. The input of sand into the dunes contributes to a diverse ecosystem, as the sand can bury climax vegetation and make it possible for pioneer vegetation to recolonise. Ideally, coastal dunes should combine both: provide safety from marine flooding and have a diverse ecosystem. To do this, measures to change sand dikes into dynamic systems are increasingly being implemented. This requires us knowing when to expect aeolian sand transport. The main aim of this thesis is therefore to better understand the timing of aeolian transport on a narrow beach, and to identify and elucidate key factors that determine this timing, with a focus on timescales from months to years. To reach this aim, I examined a long-term data set of video images of Egmond aan Zee, the Netherlands. Video monitoring captures signs of aeolian sand transport in the shape of sand strips, which are stripe-like, sl...

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Aeolian sand transport thresholds in excavated foredune notches

Nguyen

Hilton

Wakes

2021

Earth Surf Processes Landf

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Excavation of 'notches' in foredunes aims to facilitate sand transport through the foredune zone to enhance biodiversity and increase foredune resilience. Recent research has examined notch morphodynamics, however, the underlying aeolian processes in relation to sand transport have not been examined. This study determines:(i) the critical incident wind conditions resulting in sand transport inside the notch; and (ii) the pattern of wind flow and sand deposition/erosion inside the notch.Secondary winds are recorded using 12 ultrasonic anemometers deployed at crossnotch stations and compared with incident winds measured on a mast 6.5 m above foredune crest. Instantaneous sand transport is recorded using 12 laser particle counters located on four masts across the notch. Sand deposition is measured using erosion pins and digital surface models derived from remotely piloted aerial system.Field data are used to validate Computational Fluid Dynamic wind flow simulations to provide three-dimensional wind direction and speed contours in the notch. The study area is

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Regional versus local wind speed and direction at a narrow beach with a high and steep foredune

Cited by 15 publications

References 41 publications

Using Video Monitoring to Test a Fetch-Based Aeolian Sand Transport Model

Using Video Monitoring to Test a Fetch-Based Aeolian Sand Transport Model

Long-term video monitoring of aeolian activity on a narrow beach

Aeolian sand transport thresholds in excavated foredune notches

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