Fate of Fine Sediment from Dredger-Based Mining in a Wave-Dominated Environment at Chameis Bay, Namibia

Smith, Geoffrey G.; Weitz, Nadia; Soltau, Christoph; Viljoen, Awie; Luger, Stephen; Maartens, L.

doi:10.2112/06-0677.1

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…In turn, also the currents field can generate variations on the wave field (i.e., refraction). This phenomenon may become of great importance in areas such as transition environments characterized by the presence of river mouths or coastal areas characterized by the presence of intense local currents (e.g., rip currents, [42]).…”

Section: Hydrodynamic Modelingmentioning

confidence: 99%

Mathematical Modeling Framework of Physical Effects Induced by Sediments Handling Operations in Marine and Coastal Areas

Lisi

Feola

Bruschi

et al. 2019

JMSE

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In recent years increasing attention has been paid to environmental effects that may result from marine dredging and disposal operations. In general, the fine-grained fraction of handled sediments can be dispersed far from the intervention site as a turbidity plume, depending on the specific site and operational parameters. Starting from a literature review, this paper suggests standards for estimating and characterizing the sediment source term, for setting up far-field modeling studies and analyzing numerical results, with the aim of optimizing, also from an economic point of view, the different project, execution and monitoring phases. The paper proposes an integrated modeling approach for simulating sediment dispersion due to sediment handling operations in different marine-coastal areas (off-shore, near-shore and semi-enclosed basins). Attention is paid to the characterization of sediment source terms due to different operational phases (removal, transport and disposal). The paper also deals with the definition of accuracy level of modeling activities, with regard to the main physical processes characterizing the different marine–coastal areas and to the type of environmental critical issues near the intervention site (if any). The main relationships between modeling and monitoring are given for the different design and management phases to support the selection of appropriate technical alternatives and monitoring actions and to ensure the environmental compliance of the proposed interventions.

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Section: Hydrodynamic Modelingmentioning

confidence: 99%

Mathematical Modeling Framework of Physical Effects Induced by Sediments Handling Operations in Marine and Coastal Areas

Lisi

Feola

Bruschi

et al. 2019

JMSE

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“…Methods have advanced from water column total suspended solids (TSS) and seabed sampling to include optical, acoustic, and remote sensing techniques. Commonly accepted methodologies include but are not limited to (1) observing the deposition of "new" sediment on the seabed in the vicinity of the dredge site either directly, via seabed sampling (e.g., Nichols et al 1990;Black and Parry 1999;Hitchcock and Bell 2004;Kim and Lim 2009) or indirectly, via sidescan sonar and/or bathymetric changes (e.g., Hitchcock and Bell 2004;Smith et al 2008); (2) water column sampling prior to and throughout dredging (e.g., Nichols et al 1990;Pranovi et al 2004;Smith et al 2008); (3) optical monitoring via optical backscatter (OBS) measurements or other optical methods (e.g., Downing et al 1981;Downing 1983;Hamilton et al 1998;Smith et al 2008); (4) acoustic tracking of dredged sediment plumes throughout the water column (e.g., Land and Bray 2000;Reine et al 2002;Gartner 2004;Hitchcock and Bell 2004); and (5) remote sensing (i.e., Landsat TM and MODIS) of dredging vessels and associated turbidity plumes (e.g., Jorgensen and Edelvang 2000;Wu et al 2007). Although a detailed comparison of the effectiveness of these methods is beyond the scope of this document, note that none of these methodologies provide any quantitative data on the origin of the sediment they are tracking.…”

Section: Constraining Dredging Impactsmentioning

confidence: 99%

A guide for using geochemical methods in dredged material, sediment tracking, and sediment budget studies

Wadman¹,

Perkey²,

Seiter³

et al. 2017

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The U.S. Army Engineer Research and Development Center (ERDC) solves the nation's toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation's public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default.

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“…As a consequence, fine sediments can reach far further and spread over much larger areas. The life span of a plume is measured on a scale of hours, but bottom transport of deposited sediments can last for weeks after disposal (Smith et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Effects of dredging operations on the demersal fish fauna of a South American tropical–subtropical transition estuary

Barletta

Cysneiros

Lima

2016

Journal of Fish Biology

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Changes in the environment and in the composition of fish assemblages in the Paranaguá Estuary (South Brazil) were assessed by comparisons made before, during and after dredging operations, in the same months and areas studied in the previous year. Interactions between year and month were observed for salinity. During the dredging year fish total density was 2 individuals m(-2) and with a total biomass of 104 g m(-2) (among 31 species captured). For the same period the year before, 0·3 individuals m(-2) and 3 g m(-2) were captured (38 species). The number of species showed significant time v. month interactions, assuming that fish species composition varied for both year and month. Total mean density and biomass showed significant differences for interaction time v. month, and density and biomass in the dredging month September 2001 in the main channel were scientifically different from other months. Interaction times v. area were significant for Cathorops spixii (increased biomass), Aspistor luniscutis (increased density), Menticirrhus americanus (decreased biomass) and Cynoscion leiarchus (decreased density and biomass). This suggests that during the dredging process there is a change in the structure of the demersal fish assemblage. The impact (damage and mortality) induced by dredging on the macrobenthic animals along the dredge path attracted adults of C. spixii that reached densities 10 times greater than in the year before. On the other hand, sciaenid species practically disappeared. To contribute to the conservation of the estuarine fish fauna, and maintain fisheries production of the Paranaguá Estuary and surrounding areas, it is recommended that, dredging should be done from the late rainy season to the early dry season. Decisions must take into account the ecological cycles of socio-economically important fish species and prioritize the safe disposal of dredged spoils.

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Fate of Fine Sediment from Dredger-Based Mining in a Wave-Dominated Environment at Chameis Bay, Namibia

Cited by 8 publications

References 13 publications

Mathematical Modeling Framework of Physical Effects Induced by Sediments Handling Operations in Marine and Coastal Areas

Mathematical Modeling Framework of Physical Effects Induced by Sediments Handling Operations in Marine and Coastal Areas

A guide for using geochemical methods in dredged material, sediment tracking, and sediment budget studies

Effects of dredging operations on the demersal fish fauna of a South American tropical–subtropical transition estuary

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