Experimental investigation of slope sediment resuspension characteristics and influencing factors beneath the internal solitary wave-breaking process

Abstract

To define the transformation steps and understand the influence of the breaking process of internal solitary waves (ISWs) on slope sediments, experiments were conducted to study the interactions between continuous ISWs and slopes. Varying slopes were constructed based on the bottom shape and sediment composition of the northern South China Sea. The changes in the suspended sediment concentration (SSC) were then observed during the shoaling and breaking of ISWs on uniform slopes. The results showed that different types of slope sediments were suspended simultaneously at the wave-breaking position when ISW troughs arrived. After 0.5–4 min, the SSC declined slowly. Each suspension process was similar when the ISWs arrived at continuing intervals of 10 min, but the redeposition process varied for different sediments. Clayey silt and fine sand were not restored to the initial concentration in any of the deposition processes. With continued ISWs, this SSC bias increased and a nepheloid layer gradually formed. The sediment resuspension and deposition processes at the splitting deformation position were similar to those at the wave-breaking position; however, the maximum SSC was only one third to one fifth of the former. The capacity of the ISW to suspend sediments was affected by the seabed slope angle, sediment state (shear strength), wave velocity, and sediment type. The results obtained were not consistent with the experimental results (presented in this study) using traditional sediment resuspension criteria. In future research, modified criteria should thus include relevant parameters reflecting the effects of the sediment state and seabed slope angle on stress.