Evolution of sand waves in the Messina Strait, Italy

Abstract

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.

The role of Internal Solitary Waves on deep-water sedimentary processes: the case of up-slope migrating sediment waves off the Messina Strait

“…S1), and thus magnitude and orientation of fluid stresses that would result from passage of ISWs, is at the base of the sand waves formation. The hypothesis of ISWs that can remobilize the bottom sediment according to the spatial pattern of the sand-wave field is supported by current-meter and hydrographic measurements, as well as by a numerical experiment5820 (Fig. 3; Supplementary Movie S1).…”

“…4], and its morphodynamic is relevant for pipelines stability25. Monitoring of a pipeline that brings Algerian gas to the European mainland revealed that some portions of the pipe are exposed above wave troughs while other segments are buried under sandy-gravelly sediment, providing evidence that the sand-waves are mobile25. These studies hypothesize a migration rate from 10 −2 to 1 m/year, based on semi-quantitative considerations25.…”

“…Santoro et al [ref. 5] report differences in the geometry of the sand waves among repetitive bathymetric surveys conducted in 1991 and 2001. The height of the bedforms increased approximately twofold everywhere in the field, whereas their wavelength decreased at depth lesser than 218 m, suggesting reworking and/or migration of sand-waves.…”

“…The height of the bedforms increased approximately twofold everywhere in the field, whereas their wavelength decreased at depth lesser than 218 m, suggesting reworking and/or migration of sand-waves. The sand-wave field is characterized by coarse sediment with grain size that ranges from coarse sand to gravel, suggesting the presence of high bottom velocities able to mobilize the grains and remove finer material35.…”

“…Santoro et al [ref. 5] attributed this bottom current to a combination of tidal, upwelling, and thermohaline effects, and suggested that the migration velocity of the sand waves decreases with increasing depths due to differences in the hydrodynamic forcing. None of these hypotheses, however, takes into consideration the role of internal waves propagating along the LIW-TSW interface678 and their shoaling effects910.…”