Numerical modeling of suspended sediment due to deep‐sea mining

Abstract

A numerical model was developed in order to estimate the residence time of a sediment plume generated by potential deep‐sea mining activities, with special attention to discharges in the bottom boundary layer. The site of the Disturbance and Recolonization Experiment (DISCOL) in the Peru Basin in the southeast Pacific Ocean was chosen as a case study. The model includes the actual bathymetry, as well as the characteristic flow patterns of this region. Various aspects affecting the transport and sedimentation of the plume, such as stratification, flocculation in a sediment‐laden water column, and the hydrodynamics are discussed in conjunction with field data and studied with the overall aim of providing a reliable risk assessment of deep‐sea mining environmental impacts.

Estimation of Sediment Properties during Benthic Impact Experiments

“…This parameter gives an indication of the total volume discharged during the operation, which can be related to other observations of sediment resettlement and transportation in and around the area of disturbance, using transmissometers, sediment traps and other techniques (Fukushima, 1995;Trueblood et al, 1997;Yamazaki et al, 1997a;1997b) as well as in modeling the dispersion of resuspended sediment (Zielke et al, 1995;Jankowski et al, 1996;Nakata et al, 1997;Doi et al, 1999).…”

Understanding Mn-nodule distribution and related deep-sea mining impacts using AUV-based hydroacoustic sensing and optical observations

“…These data finally contributed to the development of sediment plume distribution models Lavelle et al (1981); Jankowski et al (1996) and led to interpolated blanketing maps Barnett and Suzuki (1997); Yamazaki et al (1997). Observations from these large-scale BIEs (OMI, OMA, OMCO (1978), DISCOL (1989), BIE-II (1993), JET (1994), IOM-BIE (1995), INDEX (1997), MMAJ (1997)) indicated different distribution distances of the created bottom plume ranging from several tens of meters Barnett and Suzuki (1997); Trueblood et al (1997) ;Sharma 5 (2001) up to several kilometers away from the disturbances Burns (1980); Lavelle et al (1981); Jankowski et al (1996); Yamazaki et al (1999). The use of different disturbance gear for different duration per BIE leads to inconsistent interpretations Jones et al (2000).…”

“…Plume model results are based on several assumptions to include parameters describing 15 the environment. Particle sizes and settling velocities are key factors in modelling plume distribution distances Jankowski et al (1996) and uncertainties can lead to miss-interpretations. Our current understanding of the behavior of re-suspended particles in the deep sea is based on laboratory experiments.…”

Kinetics of suspensions in the coastal zone of the sea

“…We propose a model of the vertical profile of mass concentration of suspensions based on the relationship between the parameters of the probability distribution and the characteristics of the velocity field of the surface waves in the shallow-water zone. The requirements to the composition of the "Donnaya Stantsiya" measurement system (following from theoretical concepts) are analyzed.In analyzing the grain-size composition of suspensions in the bulk of oceanic waters, the attention of the researchers is mainly given to the difficulties connected with large variations of the densities of particles of different diameters and possible mass flows through the spectrum caused by the complex mechanisms of interaction of various biogenic fractions [1,2]. In the coastal zone, where terrigenous suspensions are predominant, the solid particles have, for the most part, the same density.…”

“…In analyzing the grain-size composition of suspensions in the bulk of oceanic waters, the attention of the researchers is mainly given to the difficulties connected with large variations of the densities of particles of different diameters and possible mass flows through the spectrum caused by the complex mechanisms of interaction of various biogenic fractions [1,2]. In the coastal zone, where terrigenous suspensions are predominant, the solid particles have, for the most part, the same density.…”