Flume experiments were conducted to study the formation and development of sand waves under the unidirectional and periodic flows. Through analyzing the seabed morphology with silicon sands and model sands, the characteristic scale and evolution process of sand waves are quantitatively described. The effects of the main influential parameters on the characteristic dimension of sand waves are investigated. Both the characteristic wave height and wavelength of sand waves increase with the Froude number, increases with the nondimensional period. The characteristic dimension of sand waves for silicon sand are usually larger than those for model sands.
Submarine sand waves are approximately regular undulating bedforms, which are usually developed on the continental shelves, where strong hydrodynamics are dominant. The forms and scales of sand waves are in diversity, with the characteristic wave lengths from several meters to up to hundreds of meters. Sand waves can migrate up to tens of meters per year, and are formed at a time scale of 1-10 years (Campmans et al., 2017). Any continental shelf with directional flow is suitable for the development of submarine sand waves, such as estuaries, coast, and tidal channels etc. (e.g., Cheng et al., 2004; Wang et al., 2007; Kennedy et al., 2008; Ma et al., 2012). Sand waves are often in movable status under the residual currents. The migration of submarine sand waves will have important influences on offshore engineering, such as causing the suspension or burial of submarine pipelines, silting-up the navigation channels, breaking of submarine cables and other disasters (Zhang et al., 2006). Therefore, diminishing and preventing, to the maximum extent, engineering accidents caused by marine geological disasters, has become one of the major topics in the field of offshore engineering. It is of great scientific value and engineering significance to study the development, evolution and migration of submarine sand waves to reveal the occurrence and development process of these kinds of geological disasters.