Experimental study on sediment transport and deposition in horizontal sediment-laden jets under combined wave–current conditions

Sewage discharged into the ocean is a common type of low-concentration sediment-laden jet. Suspended sediments within jet body would exhibit distinctive transport and deposition characteristics under coastal dynamics. While waves and currents are prevalent dynamic factors in offshore areas, they have not been extensively considered in previous research. This study experimentally investigates the sediment transport and deposition characteristics of sediment-laden jets under combined wave-current conditions. It was found that under wave-current conditions, sediment transport exhibits periodic behavior over a wave cycle, with particles following the jet near the outlet and gradually settling under gravity after detaching downstream. Also, wave-current interaction enlarges the spatial extent of sediment transport compared with current-only conditions. In terms of deposition, the longitudinal deposition profile shifts downstream under wave-current conditions. Increasing wave height reduces the maximum unit-width deposition rate and drives its peak location further downstream. In contrast, current velocity mainly influences the downstream position of the peak deposition rate, with a relatively minor effect on its magnitude.