Plume dispersion modelling using dynamic representation of trailer dredger source terms

Spearman, J.; Bray, R.N.; Land, Judith; Burt, T.N.; Mead, C.T.; Scott, Derek B.

doi:10.1016/s1568-2692(07)80025-8

Cited by 8 publications

(5 citation statements)

References 12 publications

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“…Modelling of the plume experiments was reproduced using the SEDPLUME-RW 3D lagrangian dispersion model 56 which incorporates a near-field integral plume model 57,58 (based on the formulation by Lee and Cheung 59 ) to reproduce the rapid initial mixing caused by the plume jet following release. In the far-field phase turbulent mixing is reproduced through randomly moving particles by small amounts based on the eddy diffusivity, although the main mixing effect is the large-scale shear dispersion caused by spatial gradients in current speed 60 .…”

Section: Laboratory Settling Tests During the Cruise Samples Of The mentioning

confidence: 99%

Measurement and modelling of deep sea sediment plumes and implications for deep sea mining

Spearman

Taylor

Crossouard

et al. 2020

Sci Rep

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Deep sea mining concerns the extraction of poly-metallic nodules, cobalt-rich crusts and sulphide deposits from the ocean floor. The exploitation of these resources will result in adverse ecological effects arising from the direct removal of the substrate and, potentially, from the formation of sediment plumes that could result in deposition of fine sediment on sensitive species or entrainment of sediment, chemicals and nutrients into over-lying waters. Hence, identifying the behaviour of deep-sea sediment plumes is important in designing mining operations that are ecologically acceptable. Here, we present the results of novel in situ deep sea plume experiments undertaken on the Tropic seamount, 300 nautical miles SSW of the Canary Islands. These plume experiments were accompanied by hydrographic and oceanographic field surveys and supported by detailed numerical modelling and high resolution video settling velocity measurements of the in situ sediment undertaken in the laboratory. The plume experiments involved the controlled formation of benthic sediment plumes and measurement of the plume sediment concentration at a specially designed lander placed at set distances from the plume origin. The experiments were used as the basis for validation of a numerical dispersion model, which was then used to predict the dispersion of plumes generated by full-scale mining. The results highlight that the extent of dispersion of benthic sediment plumes, resulting from mining operations, is significantly reduced by the effects of flocculation, background turbidity and internal tides. These considerations must be taken into account when evaluating the impact and extent of benthic sediment plumes.Background. There is increasing global concern over the long-term availability of secure and adequate supplies of critical raw materials, known as E-tech elements, which have an essential contribution to emerging 'green' technologies 1 . These E-tech elements are present (in different concentrations and combinations) in poly-metallic nodules on the ocean floor and cobalt-rich crusts on seamounts 2 . Additionally, seafloor massive sulphide deposits contain economically attractive concentrations of a variety of minerals including copper, gold, silver and zinc 3 . Plans to extract these minerals involve a seafloor harvester, creating sediment disturbance through its motion across the sea bed, cutting of the substrate, collection of the minerals, discharge of uneconomic sediment after processing and, potentially, discharge of over-burden covering buried deposits 4-7 . Such operations will remove substrate (and any ecology bound to, or buried within, the substrate), and also generate turbidity plumes that may result in deposition of sediment onto sensitive species in the near to far-field and/or entrainment of sediment, nutrients and chemicals into over-lying waters.A review of previous sediment resuspension experiments 8 describes the various deep sea plume experiments undertaken to date 9-13 . These experiments mainly consisted of towed ha...

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Section: Laboratory Settling Tests During the Cruise Samples Of The mentioning

confidence: 99%

Measurement and modelling of deep sea sediment plumes and implications for deep sea mining

Spearman

Taylor

Crossouard

et al. 2020

Sci Rep

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“…Suspended sediment concentrations (SSC) were modelled using a tailored version of DREDGEMAP, an enhancement of SSFATE [48], a three-dimensional sediment transport and fates model, jointly developed by Applied Science Associates Pty Ltd and the U.S. Army Corps of Engineers (USACE) Environmental Research and Development Center (ERDC). The model has been successfully applied in coastal and estuarine settings [59][60][61]. The model represents the total mass of sediments suspended over time by a defined sub-sample of Lagrangian particles, allocating an equal proportion of the mass to each particle, where the transport, dispersion and settling of suspended sediment released to the water column is calculated using a random-walk procedure.…”

Section: Sediment Transport Modelmentioning

confidence: 99%

Hydrodynamic and Sediment Modelling within a Macro Tidal Estuary: Port Curtis Estuary, Australia

Dunn¹,

Zigic²,

Burling³

et al. 2015

JMSE

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An understanding of sediment transport processes and resultant concentration dynamics in estuaries is of great importance to engineering design awareness and the management of these environments. Predictive modelling approaches provide an opportunity to investigate and address potential system responses to nominated events, changes, or conditions of interest, often on high temporal and spatial resolution scales. In this study, a three-dimensional hydrodynamic model and wave model were validated and applied to generate forcing conditions for input into a sediment transport model for the period 7 May 2010-30 October 2010 within a macro tidal estuary, Port Curtis estuary (Australia). The hydrodynamic model was verified against surface and near-bottom current measurements. The model accurately reproduced the variations of surface and near-bottom currents at both a mid-estuary and upper-estuary location. Sediment transport model predictions were performed under varying meteorological conditions and tidal forcing over a 180-day period and were validated against turbidity data collected at six stations within Port Curtis estuary. The sediment transport model was able to predict both the magnitudes of the turbidity levels and the modulation induced by the neap and spring tides and wind-wave variations. The model-predicted (converted) turbidity levels compared favourably with the measured surface water turbidity levels at all six stations. The study results have useful practical application for Port Curtis estuary, including providing predictive capabilities to support the selection of locations for monitoring/compliance sites.

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“…However, recent studies have indicated that when dredging occurs in very shallow water depths the proportion of the overflow that forms a surface plume can become much larger (L. De Wit, Technical University of Delft, personal communication). For a detailed description of the near-field mixing processes occurring in the vicinity of the dredger and for the representation of these processes the reader is referred to Spearman et al (2003Spearman et al ( , 2007Spearman et al ( , 2011a and HR Wallingford (2013).…”

Section: Maritime Engineeringmentioning

confidence: 99%

Prediction of the overflow of sediment from trailer dredgers

Spearman¹

2014

Proceedings of the Institution of Civil Engineers - Maritime En

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This paper describes a model of the sediment transport processes inside the hopper of a trailer suction hopper dredger. The model is part of the TASS system -a software program that enables the user to predict the spatial development and concentration of turbidity plumes arising from dredging activities by trailer suction hopper dredgers. TASS has been developed because of a recognised need by the dredging industry to improve the quality of predictions of the effects of dredging in environmental impact assessments. This paper describes the hopper process model and the validation of overflow predictions against validation measurements off the Dutch, German and Australian coasts. The model is shown to perform well in quantitative comparisons with data for dredging silt and sand in the Netherlands and Germany. A more qualitative comparison in Australia (owing to uncertainty in the nature of the soil being dredged) also indicates the hopper process model predicts the correct range of sediment discharge.

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Plume dispersion modelling using dynamic representation of trailer dredger source terms

Cited by 8 publications

References 12 publications

Measurement and modelling of deep sea sediment plumes and implications for deep sea mining

Measurement and modelling of deep sea sediment plumes and implications for deep sea mining

Hydrodynamic and Sediment Modelling within a Macro Tidal Estuary: Port Curtis Estuary, Australia

Prediction of the overflow of sediment from trailer dredgers

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