Suspension and transportation of sediments in submarine canyon induced by internal solitary waves

Abstract

The submarine canyon was the main channel for the transport of sediment to the deep sea, but the transport process in submarine canyon induced by internal solitary waves (ISWs) had not yet been conducted. Based on computational fluid dynamics, this study investigated sediment resuspension and transport induced by the interaction between ISWs and submarine canyon. The simulations showed that sediment particles near the canyon were resuspended due to the propagation of ISWs. The sediment of slope section experienced higher resuspension rates compared to the horizontal section. Sediments on the slope were suspended before the trough of ISW and then transported into the canyon. Sediment resuspension induced by ISWs was more significant in the slope section compared to the horizontal sections and contained 45% more sediment particles than the horizontal section within the canyon. The sediment concentration within the canyon gradually increased in both the horizontal and slope sections, with a particularly pronounced increase at the junction between the horizontal and slope section. The concentration of particles in the canyon was significantly higher than in the horizontal section, with an increase in 2.73 times. Furthermore, the sediment concentration within the canyon was 1.73 times higher than outside the canyon. A sediment water column with higher suspended matter concentration, known as the bottom nepheloid layer, was formed above the submarine canyon. However, these sediment particles could not cross the pycnocline and accumulated in the upper region of the lower water. The sediment distribution of the canyon was much greater than outside the canyon within the transverse section, with three times more sediment particles within the canyon compared to outside. The sediment distribution of slope section was significant more than the horizontal section. Sediment suspended above the canyon gradually moved downstream along the submarine canyon and primarily deposit at the junction between the horizontal and slope sections. Sediment movement also occurred along the submarine canyon in the horizontal section. The interaction between ISWs and submarine canyons intensified sediment resuspension and significantly affected the spatial distribution of sediment particles. This interaction could transport resuspended sediments from the continental shelf to the deep-sea basin, thereby influencing the deep-sea environment.