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Laurent O. Amoudry

Other affiliations: Cornell University
Bio: Laurent O. Amoudry is an academic researcher from National Oceanography Centre. The author has contributed to research in topics: Sediment transport & Sediment. The author has an hindex of 13, co-authored 55 publications receiving 639 citations. Previous affiliations of Laurent O. Amoudry include Cornell University.


Papers
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Journal ArticleDOI
TL;DR: A review of state-of-the-art Eulerian implementations of bottom-up sediment transport and morphological change in coastal ocean hydrodynamic models can be found in this article.
Abstract: [1] Modern coastal ocean modeling systems are now capable of numerically simulating a variety of coastal and estuarine problems and can thus provide useful information for managing coastal zones. Here we review state-of-the-art Eulerian implementations of bottom-up sediment transport and morphological change in coastal ocean hydrodynamic models. In order to investigate the fate of suspended sediment in coastal and estuarine waters as well as the evolution of sea or river beds, sediment dynamics need to be represented at a scale relevant to the numerical discretized solution, and significant effort is devoted to parameterize sediment processes. We discuss boundary layer hydrodynamics and the computation of the bed shear stress. We also focus on approaches used to represent near-bed processes such as bed load transport and sediment erosion and deposition. Sediment diffusivities, settling velocities, and cohesive processes such as flocculation all have an impact on suspended sediment throughout the water column. We then describe the implementation of process parameterizations in coastal hydrodynamic models, explicitly reviewing five widely used systems. The approaches implemented in these coastal models may present distinct strengths and shortcomings with regard to some important issues for coastal zones, both numerical and physical. While these detailed limitations need to be considered as part of model assessment, more general issues also hinder present state-of-the-art models. In particular, sediment transport is inherently highly empirical, which is further compounded by issues arising from turbulence closure schemes. We conclude by suggesting some possible directions toward improving sediment dynamics understanding and coastal-scale predictive ability.

133 citations

Journal ArticleDOI
TL;DR: In this paper, a two-phase model for sand transport in sheet flow regime is introduced, which uses a collisional theory and a k − ǫ fluid turbulence closure to respectively model the sediment and fluid phase stresses.
Abstract: [1] We introduce a two-phase model for sand transport in sheet flow regime. This model uses a collisional theory and a k – ɛ fluid turbulence closure to respectively model the sediment and fluid phase stresses. The sediment stress closure adopts a balance equation of sediment particle fluctuation energy based on kinetic theory that incorporates two-way interactions between fluid and sediment phases. The fluid turbulence closure also considers the two-way interaction between fluid turbulence and sand particles. Model-data comparisons for the sheet layer for oscillatory flows in a U-tube and for open channel flows demonstrate the model's predictive skill. For steady open channel flows the fluid phase velocity follows closely the law of wall (i.e., the log-profile) in which the von Karman constant is reduced and the equivalent roughness is increased, compared to the clear fluid flow conditions. The model also provides information in the near-bed region where the transition from the solid-like to the fluid-like behavior of sediment particles is resolved and both the bed load layer thickness and bed load transport rate can be evaluated. For unsteady flows, this model can predict time evolutions for sediment transport throughout the water column.

83 citations

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional, two-phase model for non-cohesive sediment transport is presented, which solves concentration-weighted averaged equations of motion for both fluid and sediment phases.

40 citations

Journal ArticleDOI
TL;DR: In this article, a concentration-dependent Schmidt number description and two near-bed boundary conditions, empirical pickup and reference concentration, were investigated for a dilute two-phase sediment transport model with a k-ɛ fluid turbulence closure.
Abstract: [1] In this paper we investigate a concentration-dependent Schmidt number description and two near-bed boundary conditions, empirical pickup and reference concentration, for a dilute two-phase sediment transport model with a k-ɛ fluid turbulence closure. The pick-up approach adopts an empirical formula to calculate the upward sediment flux, whereas the reference concentration approach relates the upward sediment flux to the concentration at a reference location above the initially undisturbed bed. Through model-data comparisons with data measured in the U tube, we show that the variation of Schmidt number only affects the magnitude of calculated concentration and is insensitive to the predicted phase of concentration time histories. The predicted phase is found more sensitive to the near-bed sediment boundary condition. A concentration-dependent Schmidt number is then introduced, which improves the predictions of magnitude and phase of concentration. Using the concentration-dependent Schmidt number, the reference concentration approach generally predicts suspended sediment concentration better than the pick-up approach does.

39 citations

Journal ArticleDOI
TL;DR: A three-step selection process is proposed to ensure the best likelihood of site-specific work being useful for up-scaling activities, increasing the understanding of benthic biogeochemistry at the UK-shelf scale.
Abstract: Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-funded research programme investigating biogeochemistry in shelf seas. A three-step selection process is proposed in which (1) a target area representative of UK shelf sediment heterogeneity is selected, (2) the target area is assessed for spatial heterogeneity in sediment and habitat type, bed and water column structure and hydrodynamic forcing, and (3) study sites are selected within this target area encompassing the range of spatial heterogeneity required to address key scientific questions regarding shelf scale biogeochemistry, and minimise confounding variables. This led to the selection of four sites within the Celtic Sea that are significantly different in terms of their sediment, bed structure, and macrofaunal, meiofaunal and microbial community structures and diversity, but have minimal variations in water depth, tidal and wave magnitudes and directions, temperature and salinity. They form the basis of a research cruise programme of observation, sampling and experimentation encompassing the spring bloom cycle. Typical variation in key biogeochemical, sediment, biological and hydrodynamic parameters over a pre to post bloom period are presented, with a discussion of anthropogenic influences in the region. This methodology ensures the best likelihood of site-specific work being useful for up-scaling activities, increasing our understanding of benthic biogeochemistry at the UK-shelf scale.

31 citations


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Journal Article
TL;DR: In this paper, the size distribution of bedload in paved gravel-bed streams was studied and a method for calculating bedload size distribution that accounts for deviation from similarity was developed.
Abstract: Field data are used to study the size distribution of bedload in paved gravel-bed streams. Similarity analysis yields the results that all grain size ranges are of approximately equal transportability when the critical condition for breaking the pavement is exceeded. This result is only approximately correct due to deviations from similarity. However, it is adequate to justify development of a method for calculating total bedload, which requires only the subpavement median grain size rather than the size distribution. A method for calculating bedload size distribution that accounts for deviation from similarity is also developed.

606 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarized the most up-to-date knowledge about sea level rise and its causes, highlighting the regional variability that superimposes the global mean rise.
Abstract: Global warming in response to accumulation of human-induced greenhouse gases inside the atmosphere has already caused several visible consequences, among them increase of the Earth's mean temperature and ocean heat content, melting of glaciers, and loss of ice from the Greenland and Antarctica ice sheets. Ocean warming and land ice melt in turn are causing sea level to rise. Sea level rise and its impacts on coastal zones have become a question of growing interest in the scientific community, as well as in the media and public. In this review paper, we summarize the most up-to-date knowledge about sea level rise and its causes, highlighting the regional variability that superimposes the global mean rise. We also present sea level projections for the 21st century under different warming scenarios. We next address the issue of the sea level rise impacts. We question whether there is already observational evidence of coastal impacts of sea level rise and highlight the fact that results differ from one location to another. This suggests that the response of coastal systems to sea level rise is highly dependent on local natural and human settings. We finally show that in spite of remaining uncertainties about future sea levels and related impacts, it becomes possible to provide preliminary assessment of regional impacts of sea level rise. http://onlinelibrary.wiley.com/doi/10.1002/2013EF000188/abstract

308 citations

Book ChapterDOI
01 Jan 1840

241 citations

Journal ArticleDOI
TL;DR: A method of feedback for the bed roughness is presented, which reduces uncertainty in the prediction of both transport rates and flow velocities in the Telemac sediment transport model.

144 citations

Journal ArticleDOI
TL;DR: In this article , the environmental impacts of renewable energy source (RES) based power plants are analyzed through a comprehensive review considering solar thermal, solar photovoltaic, wind, biomass, geothermal, hydroelectric, tidal, ocean current, oceanic wave, ocean thermal, and osmotic effects.
Abstract: Renewable energy source (RES) based electrical power plants are widely considered green and clean due to their contribution to decarbonizing the energy sectors. It is apparent that RESs do not produce carbon dioxide, however their significant negative impacts on the environment are still found and cannot be ignored. In this paper, the environmental impacts of RES based power plants are analyzed through a comprehensive review considering solar thermal, solar photovoltaic, wind, biomass, geothermal, hydroelectric, tidal, ocean current, oceanic wave, ocean thermal, and osmotic effects. Solar thermal power is well known as concentrated solar power. A strength, weakness, opportunity, and threat (SWOT) analysis is carried out and discussed for all RES based power plants. Comparative SWOT analyses for solar photovoltaic and concentrated solar power plants are presented. The comparative environmental impact analyses for all existing RES based power plants are tabulated for various attributes. These attributes include but are not limited to human health, noise, pollution, greenhouse gas emission, ozone layer depletion, toxification, flooding, impact on inhabitants, eutrophication, dried up rivers, and deforestation. Based on the analysis, it is found that careful selection of RES for electrical power plants is necessary because improper utilization of RES could be very harmful for the environment.

139 citations