Migrating sand waves

Besio, Giovanni; Blondeaux, Paolo; Brocchini, Maurizio; Vittori, Giovanna

doi:10.1007/s10236-003-0043-x

Cited by 31 publications

(26 citation statements)

References 17 publications

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“…On the contrary, in the examined One possible explanation could be found in the hypothesis of a differential migration as a function of depth. More particularly, as far as field migration is concerned, Besio et al (2003a) showed that it is due to the presence of tidal constituents superposed on a main oscillatory component, which break the symmetry of the flow field close to the bottom. Quantitative results of Besio et al (2003a), who studied the effect of the superposition on M2 of either Z0 or M4, cannot be used here, because hydrodynamic characteristics are very different: although M2 is the main component, both Z0 and M4 are very small.…”

Section: Comparison Between Field Measurements and Discussion Of Resultsmentioning

confidence: 99%

“…Then, the results of the two bathymetric surveys are described and an analysis of sand-wave geometric characteristics is reported along with a comparison between data from the two surveys. Observations are also compared with predictions of a theory (Besio et al 2003a) which relates sand-wave growth and migration to the main constituents of the forcing tides. The paper ends with conclusions and remarks about future research.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of sand waves in the Messina Strait, Italy

et al. 2004

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In the present paper the morphodynamics of sand waves in the Messina Strait, Italy, is analysed by comparing data gathered during two different surveys carried out in 1991 and 2001, respectively. In particular, a morphometric analysis on the most recent data and a qualitative analysis of the differences between bottom bedform patterns, are carried out. At locations characterised by greater depths, only minor changes to the planimetric configuration of the field, i.e. crest orientation (which is seen to be orthogonal to the direction of net gross sand transport) and wave length are observed, while differences in wave length and crest direction are more evident in more shallow areas. On the other hand, wave height has significantly increased in the whole field. A possible explanation of such a change, based on the previsions of a theory which relates sand-wave growth and migration to the main components of the tidal ellipse, is provided.

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Section: Comparison Between Field Measurements and Discussion Of Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution of sand waves in the Messina Strait, Italy

et al. 2004

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“…In the situation where forcing includes both the M 4 tide and a steady component, it is possible to have a migration of the bedforms against the direction of the steady current. Besio et al (2003) used this combination of currents to explain the upcurrentmigration of sand waves. A necessary condition is that the phase between the M 2 and M 4 tide is such that it introduces a residual sediment transport in the direction opposite to the residual sediment transport caused by the residual current.…”

Section: Sensitivity To Standard Deviationmentioning

confidence: 98%

A model for grain-size sorting over tidal sand ridges

2004

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A model was developed and analyzed to quantify the effect of graded sediment on the formation of tidal sand ridges. Field data reveal coarse (fine) sediment at the crests (in the troughs), but often phase shifts between the mean grain-size distribution and the bottom topography occur. Following earlier work, this study is based on a linear stability analysis of a basic state with respect to small bottom perturbations. The basic state describes an alongshore tidal current on a coastal shelf. Sediment is transported as bed load and dynamic hiding effects are accounted for. A one-layer model for the bed evolution is used and two grain size classes (fine and coarse sand) are considered. Results indicate an increase in growth and migration rates of tidal sand ridges for a bimodal mixture, whilst the wavelength of the ridges remains unchanged. A symmetrical externally forced tidal current results in a grain-size distribution which is in phase with the ridges. Incorporation of an additional external M4 tidal constituent or a steady current results in a phase shift between the grain-size distribution and ridge topography. These results show a general agreement with observations. The physical mechanism responsible for the observed grain-size distribution over the ridges is also discussed.Postprint (published version

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“…Dredging may be required because sand waves migrate into or along shipping channels and harbors, hence reducing the local water depth and, consequently, affecting the navigability. It has been recognized that near-shore, migrating sand waves might even affect shoreline evolution and coastal defense works [1]. The presence of sand waves in some particular areas is strongly correlated to the amplitude of the spring tidal current [2].…”

Section: Introductionmentioning

confidence: 99%

Sand Waves Generation: A Numerical Investigation of the Infiernillo Channel in the Gulf of California

Ley¹,

Carbajal²

2016

OJMS

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The effect of the coastal geometry on sand bed forms generation has been investigated for a tidal dominated area. Different hypothetical geometries of coastal channels with flat bottoms and unlimited sediment availability were exposed to strong oscillatory tidal currents to simulate the interaction of hydrodynamics and the bedload sediment transport. The hypothetical geometries stand for the idealization of the principal geographic features of the Infiernillo Channel, a coastal area of the Gulf of California where sandbanks and sand waves have been observed. A depth integrated hydrodynamic-numerical model and a parameterized formula to estimate the bedload sediment transport were applied coupled with a sediment conservation equation to determine the sea bottom morphodynamics. Model predictions in the Infiernillo Channel were compared to available satellite imagery. This investigation demonstrates that a vertical integrated numerical model is able to reproduce the development of incipient sand waves that exist in the Infiernillo Channel. Incipient sandbanks and shoals were also simulated. Sand waves with wavelengths of about 200 m were calculated on the same locations where sand waves actually exist. A crucial finding of this research was to show that the geometry of a shallow water basin and the presence of tidal velocity gradients associated with abrupt changes in the coastline alignment were critical in determining the sand-bed pattern generation. We demonstrate that a vertical variation of tidal currents is not necessary to generate sand waves.

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Migrating sand waves

Cited by 31 publications

References 17 publications

Evolution of sand waves in the Messina Strait, Italy

Evolution of sand waves in the Messina Strait, Italy

A model for grain-size sorting over tidal sand ridges

Sand Waves Generation: A Numerical Investigation of the Infiernillo Channel in the Gulf of California

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