A numerical investigation of the effects of deep-sea mining vehicles on the evolution of sediment plumes based on the combination of near- and far-field models

Deep-sea mining (DSM) activities continuously stir up sediments around the collectors and release dense sediment plumes, which has attracted widespread international attention due to environmental problems. Furthermore, modelling plumes will be central to the environmental impact statement for regulatory consideration. In this research, a combined near- and far-field numerical model is established to investigate the ratio of the discharge velocity of the sediment plume to the travel velocity of the deep-sea mining vehicle (DSMV). The results show that (i) the relative velocity of the released plume has a significant effect on the initial suspended sediment concentration in the passive transport phase of the plumes; (ii) the particles residence time scale has significant feedback on the relative velocity of the plumes, while the final equilibrium suspension particles rate is in contrary; (iii) increasing the relative discharge velocity of the plumes will contribute to the sedimentation of suspended sediment, but at the same time will cause a larger diffusion, and both aspects should be evaluated for application in commercial DSM activities.