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| Registros recuperados: 48 | |
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| Jourdin, Frederic; Tessier, Caroline; Le Hir, Pierre; Verney, Romaric; Lunven, Michel; Loyer, Sophie; Lusven, Andre; Filipot, Jean-francois; Lepesqueur, Jeremy. |
| A pair of self-contained acoustic Doppler current profilers (SC-ADCPs) operating with different frequencies were moored on a muddy sea bottom at about 20 m depth in the Bay of Vilaine off the French Atlantic coast. With their acoustic beams oriented upwards, the SC-ADCPs ensonified most of the water column. The results of several months of in situ recorded echo intensity data spanning 2 years (2003 to 2004) from the dual-frequency ADCPs are presented in this paper. The aim was to estimate suspended particle mass concentration and mean size. A concentration index CI is proposed for the estimation of particle concentration. Based on theory the CI-unlike the volume backscatter strength-does not depend on particle size. Compared with in situ optical data, the... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00213/32427/30896.pdf |
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| Jany, Cassandre; Pairaud, Ivane; Thouvenin, Benedicte; Verney, Romaric. |
| In the context of the METROC project, academic modelling of dissolved and particulate materials were done with the MARS3D model. Considering the dissolved materials, we calculated evacuation times and residence times. Then, we add minimal dilution and percentile maps to assimilate the modelling and the realistic dissolved metal discharge. Considering the particulate materials, we did balance sheets for material exported, sedimenting or staying in water for three different phases (whole modelling 13 October – 31 December 2008, flood situation and resuspension situation). Maps of Marseille roadstead complete that information and allow visualising the principal deposition area. We will continue this work by modelling reel material such as Lead. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00090/20088/17724.pdf |
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| Jaud, Marion; Grasso, Florent; Le Dantec, Nicolas; Verney, Romaric; Delacourt, Christophe; Ammann, Jerome; Deloffre, Julien; Grandjean, Philippe. |
| Intertidal mudflats play a critical role in estuarine exchange, connecting marine and continental supplies of nutrients and sediments. However, their complex morphodynamics, associated with a wide range of physical and biological processes, are still poorly understood and require further field investigation. In addition, mudflats are challenging areas for Structure-from-Motion (SfM) photogrammetric surveys. Indeed, the mudflats generally hold back residual tidal water, which can make stereo restitution particularly difficult because of poor correlations or sun-glint effects. This study aims to show the potential of light UAVs (Unmanned Aerial Vehicles) for monitoring sedimentary hydrodynamics at different spatial scales in a silty estuary. For each UAV... |
| Tipo: Text |
Palavras-chave: Coastal monitoring; Unmanned Aerial Vehicle; Photogrammetry; Estuary; Mudflat areas; Morphological features. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00326/43721/43167.pdf |
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| Sherwood, Christopher R.; Aretxabaleta, Alfredo L.; Harris, Courtney K.; Rinehimer, J. Paul; Verney, Romaric; Ferre, Benedicte. |
| We describe and demonstrate algorithms for treating cohesive and mixed sediment that have been added to the Regional Ocean Modeling System (ROMS version 3.6), as implemented in the Coupled Ocean-Atmosphere-Wave- Sediment Transport Modeling System (COAWST Subversion repository revision 1234). These include the following: floc dynamics (aggregation and disaggregation in the water column); changes in floc characteristics in the seabed; erosion and deposition of cohesive and mixed (combination of cohesive and non-cohesive) sediment; and biodiffusive mixing of bed sediment. These routines supplement existing noncohesive sediment modules, thereby increasing our ability to model fine-grained and mixed-sediment environments. Additionally, we describe changes to... |
| Tipo: Text |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00442/55319/56839.pdf |
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| Cayocca, Florence; Verney, Romaric; Petton, Sebastien; Caillaud, Matthieu; Dussauze, Morgan; Dumas, Franck; Le Roux, Jean-francois; Pineau-guillou, Lucia; Le Hir, Pierre. |
| The rising interest in environmental and ecosystem dynamics have lead coastal oceanographers to not only investigate the “traditional” physical parameters describing the ocean state and its dynamics (e.g. temperature, salinity, currents, water levels in coastal areas), but to also account for the dynamics of parameters describing its biogeochemical components. To that end, MARS3D regional and coastal modelling system has been coupled to ecosystem modules (ECO-MARS3D, ECO3M) as well as sediment dynamics modules (MARS3D-SEDIM): sediment, nutrient and primary production contents can be considered as the lower level environment and ecosystem descriptors of the “biogeochemical” ocean. Early investments into physical and biological analysis at the regional scale... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00194/30572/29015.pdf |
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| Dufresne, Christiane; Duffa, Céline; Rey, Vincent; Verney, Romaric. |
| L’objectif de ce travail est mettre en place un modèle hydro-sédimentaire de dispersion des radionucléides, comme outil d’aide à la décision suite à une hypothétique contamination marine accidentelle. Appliqué à la Rade de Toulon, il utilise le modèle MARS-3D pour l’étude hydrodynamique et le module MIXSED pour la dynamique des différentes classes de sédiments. Les cas d’application présentés concernent le césium et le plutonium, qui ont des affinités très différentes avec les sédiments fins. Les simulations de rejet, effectuées en fond de baie, montrent une variabilité saisonnière marquée, due aux conditions météorologiques typiques, mais aussi aux conditions de débit et de charge sédimentaire associée du fleuve Las, qui se jette dans la Rade. Ainsi, les... |
| Tipo: Text |
Palavras-chave: Modélisation hydro-sédimentaire; Dispersion; Radionucléides; Toulon. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00348/45926/45619.pdf |
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| Mietta, Francesca; Chassagne, Claire; Verney, Romaric; Winterwerp, Johan C.. |
| In this paper, we study a population balance equation (PBE) where flocs are distributed into classes according to their mass. Each class i contains i primary particles with mass m p and size L p. All differently sized flocs can aggregate, binary breakup into two equally sized flocs is used, and the floc’s fractal dimension is d 0 = 2, independently of their size. The collision efficiency is kept constant, and the collision frequency derived by Saffman and Turner (J Fluid Mech 1:16–30, 1956) is used. For the breakup rate, the formulation by Winterwerp (J Hydraul Eng Res 36(3):309–326, 1998), which accounts for the porosity of flocs, is used. We show that the mean floc size computed with the PBE varies with the shear rate as the Kolmogorov microscale, as... |
| Tipo: Text |
Palavras-chave: Flocculation; Population balance equation; Discretization into classes; Kaolinite; Natural mud; Zeta-Potential. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00028/13875/11033.pdf |
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| Gangloff, Aurelien; Verney, Romaric; Doxaran, David; Ody, Anouck; Estournel, Claude. |
| In coastal environments, river plumes are major transport mechanisms for particulate matter, nutriments and pollutants. Ocean colour satellite imagery is a valuable tool to explore river turbid plume characteristics, providing observations at high temporal and spatial resolutions of suspended particulate matter (SPM) concentration over a long time period, covering a wide range of hydro-meteorological conditions. We propose here to use the MERIS-FR (300 m) Ocean Colour archive (2002–2012) in order to investigate Rhône River turbid plume patterns generated by the two main forcings acting on the north-eastern part of the Gulf of Lions (France): wind and river freshwater discharge. Results are exposed considering plume metrics (area of extension,... |
| Tipo: Text |
Palavras-chave: River plume metrics; Sediment dynamics; MERIS; Ocean color data; Suspended particulate matter; Gulf of Lions. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00391/50258/50885.pdf |
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| Grasso, Florent; Schulz, Elisabeth; Le Hir, Pierre; Verney, Romaric; Thouvenin, Benedicte. |
| La dynamique sédimentaire à l’embouchure de l’estuaire de Seine est principalement contrôlée par les forçages hydrométéorologiques (débit, vent, vagues, marée) et les fortes pressions anthropiques (endiguement, dragage, clapage). La compréhension et la quantification de la dynamique des flux sédimentaires en suspension (sable/vase) est un enjeu majeur, autant d’un point vu écologique (ex. turbidité, envasement) que financier (ex. gestion des chenaux de navigation). La mise en place de réseaux de mesure in situ permet une meilleure compréhension de la dynamique sédimentaire de l’estuaire, mais leur caractère local rend difficile toute estimation des flux et bilans sédimentaires. Pour répondre à ces questions, cette étude s’appuie sur la modélisation... |
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Palavras-chave: Dynamique hydro-sédimentaire; Sable/vase; Estuaire de Seine; Modélisation numérique; Mesures in situ; Dragage; Flux résiduels et bilans; Année/trimestres. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00348/45928/45621.pdf |
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| Sauzade, Didier; Andral, Bruno; Gonzalez, Jean-louis; Pairaud, Ivane; Verney, Romaric; Zebracki, Mathilde; Cadiou, Jean-francois; Boissery, Pierre. |
| Marine pollution is one of the priority issues of the Mediterranean environment. This pollution comes from multiple sources including large coastal cities which are considered as hot-spots. The METROC project objective is to assess gross and net chemical contaminant flows related to large Mediterranean coastal cities, with a first application to the Marseilles area. The methodology consists of i) assessing the present state of the chemical contamination of the coastal environment; ii) assessing inputs to the sea from sewage, small rivers and storm water run-off; and iii) modelling the fate of some key contaminants, in order to attempt to establish a balance between inputs and exports towards the open sea. This short article presents a synthesis on these... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00070/18164/15721.pdf |
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| Deloffre, J; Verney, Romaric; Lafite, R; Lesueur, P; Lesourd, S; Cundy, A. |
| The objective of this study is to propose an original approach to the analysis of the formation of intertidal rhythmites, their preservation, and the evaluation of sedimentation rates on estuarine mudflats. Three mudflats, one from each of three estuaries, were analysed using a combination of long-term (>a year), high-frequency (1 burst/10 or 20 min), and high-resolution (0.2 cm) altimeter datasets and X-ray images of sediment cores collected during topographic surveys. The results highlight the roles played by sediment supply, hydrodynamics, and morphology of the lower estuaries on the sedimentation rhythms. While the sediment-starved Medway estuary (Kent, UK) remains stable at different time-scales, the annual sedimentation rates on the sheltered... |
| Tipo: Text |
Palavras-chave: Macrotidal estuary; X ray imagery; Altimeter; Rhythmites; Mud; Morphology. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3517.pdf |
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| Druine, Flavie; Verney, Romaric; Deloffre, Julien; Lemoine, Jean-philippe; Chapalain, Marion; Landemaine, Valentin; Lafite, Robert. |
| The aim of this study is to investigate the complex response of optical turbidity sensors (side- and back-scattering sensors) to Suspended Particle Matter (SPM) characteristics and the consequences when investigating SPM dynamics from long-term high frequency monitoring networks. Our investigation is based on the analysis of a unique dataset of monthly 12 h cycle measurements of SPM characteristics such as turbidity, concentration, floc size distribution, floc density and organic matter content in the macrotidal Seine Estuary (France) between February 2015 and June 2016. Results reveal that despite calibration to a Formazin standard, turbidity sensor response to SPM concentrations (in the range of 7–7000 mg L−1) are strongly variable, from the tidal scale... |
| Tipo: Text |
Palavras-chave: Turbidity; Suspended sediment concentration; Optical sensor; Flocs; Long term monitoring. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00431/54227/55550.pdf |
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| Defontaine, Sophie; Sous, Damien; Morichon, Denis; Verney, Romaric; Monperrus, Mathilde. |
| The present paper reports on a series of field experiments aiming to characterise the functioning of a man-engineered strongly forced salt-wedge estuary: the lower estuary of the Adour river, France. Bottom-moored velocity measurements and surface boat surveys have been performed under low river discharge conditions, for both neap and spring tides, in order to provide a well-documented reference framework to understand the dynamics of water masses, turbulence and suspended particulate matter (SPM) transport in the lower estuary. An additional campaign has been carried out in high river discharge conditions. This first documented in-situ study of the Adour lower estuary demonstrates its variability in terms of hydrological regimes, from salt-wedge to... |
| Tipo: Text |
Palavras-chave: Salt-wedge estuary; Estuarine circulation; Stratification; Turbulence; Suspended particles transport; Adour river. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70049/67987.pdf |
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| Fettweis, M; Toorman, E; Verney, Romaric; Chapalain, Marion; Legrand, S; Lurton, Xavier; Montereale-gavazzi, G; Roche, M; Shen, X; Van Den Eynde, Dries; Van Lancker, Vera. |
| Context To protect the marine environment more effectively, the European Union adopted the Marine Strategy Framework Directive (MSFD) in 2008, aiming to achieve the Good Environmental Status (GES) of the EU's marine waters by 2020 and to protect the resource base upon which marine-related economic and social activities depend. A major challenge in the implementation of the MSFD is to achieve the necessary scientific knowledge on the marine environment, its processes and the methods to monitor them. The focus of INDI67 is on the evaluation and development of indicators to monitor GES of descriptor 6 and 7. Seafloor integrity (descriptor 6) refers to the structure and functions of the benthic ecosystems. It relates to the comprises physical, chemical and... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00634/74632/74526.pdf |
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| Grasso, Florent; Carlier, Antoine; Cugier, Philippe; Verney, Romaric; Marzloff, Martin. |
| In coastal environments, strong feedback can exist between benthic fauna and sediment dynamics. Benthic populations can modify sediment dynamics through biofiltration and bioturbation, while hydro- and sediment dynamics directly determine local environmental conditions for benthic organisms. However, these complex feedbacks are difficult to study in situ. Here, we carried out mesocosm experiments to characterize the effects of a benthic species (the gastropod Crepidula fornicata) on mud dynamics under hydrodynamic conditions representative of their natural habitat. Different experimental tests related to the inclusion (or not) of dead or live crepidula reveal that biofiltration can increase particle settling up to 40%. Flocculation, which is strengthened... |
| Tipo: Text |
Palavras-chave: Laboratory experiments; Coastal processes; Physical-biological interactions; Benthic engineer species; Mud settling; Flocculation; Biofiltration; Organic matter. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77403/79043.pdf |
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| Registros recuperados: 48 | |
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