The Formation and Movement of Sand Bars by Wave Action

King, Chris; Williams, Wayne W.

doi:10.2307/1788907

Cited by 180 publications

(114 citation statements)

References 4 publications

Supporting

Mentioning

102

Contrasting

Unclassified

Order By: Relevance

“…Early sandbar models were based on a hydrodynamic template approach (i.e., using only the first term on the right of (4)), in which the onshore/offshore location of the bar crest was somewhat arbitrarily related to a characteristic scale of the forcing field. For example, the popular breakpoint model [King and Williams, 1949;Dally, 1987] suggested that sand should accumulate under the location of initial wave breaking. Similarly, sediment convergence might form bars at the cross-shore location of nodes or antinodes of standing wave motions [Short, 1975;Bowen, 1980].…”

Section: 2mentioning

confidence: 99%

Role of morphologic feedback in surf zone sandbar response

Plant¹,

Freilich²,

Holman³

2001

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. Several aspects of feedback mechanisms associated with surf zone sandbar response have been characterized using bathymetric surveys, sampled approximately monthly over a 16-year period at the Army Corps of Engineers' Field Research Facility (North Carolina). The measured bathymetry was alongshore averaged and modeled by the superposition of two Gaussian-shaped sandbars on an underlying planar slope. A third, half-Gaussian-shaped bar represented steepening at the shoreline. The rms error between the measured bathymetry and the profile model was 0.10 m (estimated over 322 different surveys). The model explained 99% of the profile variance that remained after first removing the linear, cross-shore trend from each observed profile. Bar response, which was extracted from the modeled profiles, was compared to a local hydrodynamic forcing variable F (F was defined as the ratio of the wave height to water depth, evaluated at bar crest locations). At low values of F (i.e., nonbreaking conditions), bars migrated onshore, and their amplitude tended to decay. At high values of F (i.e., breaking conditions), bars migrated offshore, with relatively little change in amplitude. The transition between onshore and offshore migration occurred at a value of F that was consistent with the onset of wave breaking. Bar migration was associated with a stabilizing feedback mechanism, which drove bar crests toward an equilibrium position at the wave breakpoint. However, we observed that the rate of bar response showed no reduction for any nonzero choice of F, indicating that bars never reached equilibrium. Systematic bar amplitude decay was observed under nonbreaking conditions. Bar amplitude decay could drive F farther away from breaking conditions, allowing further bar amplitude decay. This is a destabilizing feedback mechanism, potentially leading to bar destruction.

show abstract

Section: 2mentioning

confidence: 99%

Role of morphologic feedback in surf zone sandbar response

Plant¹,

Freilich²,

Holman³

2001

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…RÉSUMÉ Le littoral de la région de Mingan (moyenne Côte-Nord du golfe du SaintLaurent), se caractérise par un ensemble de cinq barres d'avant-côte parallèles se succé-dant depuis le littoral jusqu'à une profondeur de 12 m. Ces barres s'apparentent, selon la classification de Greenwood et DavidsonArnott (1979), aux barres décrites par Evans (1940) et Hom-ma et Sonu (1962). Ce type de barres diffère des crêtes et sillons pré-littoraux tels que définis par King et Williams (1949). La première barre du système de Mingan, qui fait l'objet de ce travail, représente un type particulier; elle est partiellement exondée à marée basse et soumis au dé-ferlement des vagues à marée haute.…”

Section: éVolution Morpho-sedimentaire De La Barre De Déferlement: Ununclassified

“…The Mingan area shoreline (North Shore of the Gulf of StLawrence) is characterized by five parallel nearshore bars from the beach to a depth of 12 m. These bars are related, in the classification of Greenwood and Davidson-Arnott (1979), to the bars described by Evans (1940) and Hom-ma and Sonu (1962). This bar type is different from the ridge and runnel defined by King and Williams (1949). The first bar of the Mingan area, wich is studied in this paper is particular in that it is partially exposed at low tide level and submitted to breaking waves at high tide level.…”

Section: éVolution Morpho-sedimentaire De La Barre De Déferlement: Unmentioning

confidence: 99%

“…Leur origine est attribuée, de façon générale, au transfert d'énergie entre les houles et le fond marin. Ces structures présentent des formes variées qui ont été étudiées à de nombreux sites, notamment le long des côtes australiennes (Wright era/., 1979;Short, 1979), sur les bords de la Méditerranée (King et Williams, 1949) et de la mer Noire (Zenkovitch, 1967), sur la côte est américaine (Sonu, 1973;Hayes, 1969) et au Nouveau-Brunswick (Davidson-Arnott et Greenwood, 1976).…”

Section: Introductionunclassified

See 1 more Smart Citation

Évolution morpho-sédimentaire de la barre de déferlement : un exemple dans le golfe du Saint-Laurent, Québec

Ross¹,

Long²

2007

gpq

View full text Add to dashboard Cite

Le littoral de la région de Mingan (moyenne Côte-Nord du golfe du Saint-Laurent), se caractérise par un ensemble de cinq barres d'avant-côte parallèles se succédant depuis le littoral jusqu'à une profondeur de 12 m. Ces barres s'apparentent, selon la classification de Greenwood et Davidson-Arnott (1979), aux barres décrites par Evans (1940) et Hom-ma et Sonu (1962). Ce type de barres diffère des crêtes et sillons prélittoraux tels que définis par King et Williams (1949). La première barre du système de Mingan, qui fait l'objet de ce travail, représente un type particulier; elle est partiellement exondée à marée basse et soumis au déferlement des vagues à marée haute. L'étude comprend un échantillonnage des sédiments de surface, des prélèvements de carottes et des relevés topographiques. Le haut de plage est composé de sable fin à moyen bien trié et le bas de plage, de sable grossier et mal classé. Le creux est constitué de matériel très grossier et de sable fin provenant du transfert sédimentaire de la barre vers le creux. Les sédiments de la crête et des pentes marine et terrestre de la barre sont constitués de sable moyen, modérément à bien classé. Le sommet de la barre s'érode sur une épaisseur de 20 à 25 cm sous l'action des houles de tempête et une fraction de sédiments fins se dépose dans le creux. Par temps calme, la barre tend à reprendre son profil initial (avant tempête) sous l'action des courants de marée et de dérive littorale qui siègent dans le creux et qui transportent le sédiment parallèlement à la côte. Les épaisseurs de remaniement sont alors réduites (5 cm sur la crête et 15 cm au bas de la pente terrestre et sur la pente marine).The Mingan area shoreline (North Shore of the Gulf of St-Lawrence) is characterized by five parallel nearshore bars from the beach to a depth of 12 m. These bars are related, in the classification of Greenwood and Davidson-Arnott (1979), to the bars described by Evans (1940) and Homma and Sonu (1962). This bar type is different from the ridge and runnel defined by King and Williams (1949). The first bar of the Mingan area, wich is studied in this paper is particular in that it is partially exposed at low tide level and submitted to breaking waves at high tide level. The study includes surface sediment sampling, coring and topographic survey. Upper beach sediments consist of well sorted fine to medium sand whereas lower beach sands are coarse grained and poorly sorted. The trough is made up of coarse material and fine sand transfered from the top of the bar. Sediments from landward slope, crest and seaward slope are medium grained and moderately to well sorted. The crest of the bar is eroded to a depth of 20 cm to 25 cm under storm wave action. During post-storm regime, the bar shifts from storm profile to post-storm profile in response to longshore currents with transport sediments. Then, the depth of reworking is reduced to 5 cm on the crest of the bar and 15 cm on both landward and seaward slopes.El litoral de la region de Mingan (sector medio de la costa norte del S...

show abstract

“…Previous studies of bottom geometry in the nearshore area have dealt with local topographic maxima, variously termed "bars" (Bascom 1964;Bird 1969), "low and ball" (Evans 1940), "ridge and runnel" (King and Williams 1949;King 1959) or "swash bar" (King 1959) depending on the author and the degree to which the feature was exposed to subaerial processes. Johnson (1919) and Zenkovich (1967) in their reviews of the early work in the subaqueous zone mentioned the remarkable persistence of offshore bars in certain areas, the relationship of these bars to the offshore slope, the effect of severe storms on '.he bar system, and the role of breaking waves in shaping this zone.…”

Section: Previous Researchmentioning

confidence: 99%