Waves plus currents crossing at a right angle: Sandpit case

The present paper explores the possibility of exploiting sandpits at intermediate and shallow water depths by analyzing both the hydrodynamic and the morphodynamic response in the proximity of a dredged area. More precisely, a laboratory investigation was carried out to analyze the effects of the wave-current interaction over a borrow area, particularly in terms of the morphodynamic evolution of the pit. The influence of both regular and irregular waves on the current was analyzed. It was found that the flow is significantly influenced by such interaction in the presence of the borrow area. The morphodynamic evolution of the sandpit is mainly affected by the waves, while the superimposition of a current does not introduce qualitative modifications but increases the mobilization of sediments, with repercussions on the speed of the evolution process. The results of the experimental campaign suggested that the analysis of the morphodynamic evolution can be approached at a laboratory scale. Indeed, the volume infill rate resulted in agreement with the observations in real dredged sites (CNEXO pit); moreover, the same quantity can be interpreted in the light of literature relationships proposed to describe the time evolution of noncohesive sandy beds.