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| Registros recuperados: 21 | |
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| Diaz, Melanie; Grasso, Florent; Le Hir, Pierre; Caillaud, Matthieu; Thouvenin, Benedicte. |
| Coastal environments are directly influenced by terrigenous inputs coming from rivers through estuaries. Quantifying the amount of nutrients and contaminants brought by sediments from continental areas to the sea is of major interest for marine resource protection. The complexity of the intra-estuarine dynamics, associated with the strong variability of meteorological forcing makes it difficult to quantify the residence time of particles within the estuary and the accumulation and dispersion areas offshore the mouth. Moreover, the dynamics of fine sediment trapping areas in the adjacent continental shelf (e.g. temporary or permanent storage such as the “West-Gironde Mud Patch” (WGMP) ) remains extremely challenging to address. Based on a realistic... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00514/62559/66913.pdf |
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| Grasso, Florent; Bismuth, Eliott; Verney, Romaric. |
| En se basant sur les travaux des programmes de recherche Seine-Aval 4 & 5, et plus particulièrement le modèle numérique hydro-sédimentaire MARS3D « CurviSeine » (HYMOSED-SA5), le projet ARES (« Analyse de Rejeux hydro-sédimentaires en Estuaire de Seine ») du programme de recherche Seine-Aval 6 avait pour objectifs de produire un référentiel de données validées de la dynamique hydro-sédimentaire de l’estuaire pour deux périodes de 11 ans (1990-2000 et 2005-2015). Le présent document décrit : (i) le modèle ainsi que les paramètres de modélisation (forçages, grille bathymétrique, etc…) utilisés ; (ii) la comparaison des sorties hydrologiques (température, salinité, sédiments en suspension) du modèle avec les données du réseau PHRESQUES (bouée SCENES et... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00664/77610/79628.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... |
| Tipo: Text |
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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| 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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| Grasso, Florent; Le Hir, Pierre. |
| Estuaries are subject to extensive morphological changes through human activities, such as deepening and narrowing via dredging and channelization. The estuary sediment load, characterised by the estuarine turbidity maximum (ETM), can severely increase in response to channel deepening, shifting the estuary from a natural to hyperturbid state. The main processes driving the estuarine circulation, hydrology and sediment dynamics are relatively well known. However, their relative influence on suspended sediment concentration (SSC), as well as their role in the transition toward hyperturbid estuaries, is still a subject of debate. Therefore, this study aims at investigating the relative contribution of key estuarine drivers (gravitational circulation and tidal... |
| Tipo: Text |
Palavras-chave: Estuary deepening and narrowing; Sediment dynamics; Turbidity maximum; Tidal asymmetry; Stratification; Numerical modelling; Morphological changes. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00479/59046/65965.pdf |
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| Diaz, Melanie; Grasso, Florent; Le Hir, Pierre; Sottolichio, Aldo; Caillaud, Matthieu; Thouvenin, Benedicte. |
| Coastal environments are directly influenced by terrigenous inputs coming from rivers through estuaries. Quantifying the amount of nutrients and contaminants transported by sediments from continental areas to the sea is crucial for marine resources protection. However, the complexity of estuarine dynamics makes it difficult to quantify sediment fluxes from field measurements alone and requires numerical modeling. Thus, using a realistic 3D hydrodynamic and sediment transport model, this study aims at evaluating the influence of model empirical parameters on sediment fluxes and estimating uncertainties on mud and sand transfers at a macrotidal estuary mouth. A sensitivity analysis, considering changes in sediment transport parameters, revealed that the... |
| Tipo: Text |
Palavras-chave: Sensitivity analysis; Sediment fluxes; Numerical modeling; Mud; Sand; Gironde Estuary. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00617/72897/71906.pdf |
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| Grasso, Florent; Verney, Romaric. |
| Le volet Mesures du projet SA5 HYMOSED se décompose en deux axes distincts : le suivi des évolutions morphodynamiques des vasières latérales intertidales et la quantification des matières en suspension (MES) de surface par télédétection couleur de l’eau. L’objectif du premier axe est d’évaluer notre capacité à observer les modifications morphodynamiques des vasières en comparant et combinant trois approches complémentaires (altimétrie ponctuelle ALTUS, topographie TLS (scanner laser terrestre), topographie par drone). Un suivi ALTUS sur 2 ans de trois vasières intertidales à l’aval de Tancarville (Tancarville, Pointe de la Roque, Vasière Nord) a été réalisé, permettant de quantifier l’influence des forçages hydrodynamiques et hydrologiques sur les phases... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00414/52523/53292.pdf |
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| Grasso, Florent; Le Hir, Pierre. |
| Le projet HYMOSED (« Modélisation du fonctionnement HYdro-MOrpho-SEDimentaire de l’estuaire de la Seine ») du programme de recherche Seine-Aval 5 (déc. 2013 – mar. 2017) a eu pour objectif d’apporter une meilleure compréhension du fonctionnement hydro-morpho-sédimentaire de l’estuaire de la Seine des échelles de temps événementielle à annuelle. Cela s’est traduit par : (1) une analyse fine de la dynamique du bouchon vaseux, (2) la quantification des flux et bilans sédimentaires (sables/vase) pour différents scénarios hydrométéorologiques caractéristiques et (3) l'analyse de l’évolution morpho-sédimentaire à l'embouchure. Afin de répondre de manière pertinente à ces questions, ce projet s’est appuyé sur un important travail de validation du modèle... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00412/52381/53170.pdf |
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| Bacq, Nicolas; Cugier, Philippe; Grasso, Florent; Le Gendre, Romain; Le Hir, Pierre; Lemoine, Jean-philippe; Riou, Philippe; Schulz, Elisabeth; Thouvenin, Benedicte; Verney, Romaric. |
| Dans le cadre du programme de recherche Seine-Aval 5, différentes stratégies de modélisation numérique sont mises en place pour aider à répondre aux questionnements scientifiques et sociétaux associés au fonctionnement physique, biologique, chimique et écologique de l'estuaire de la Seine (ex. projets RESET et HYMOSED). Les forçages météo-marins (vent, vague, marée) et hydrologique (débit) contrôlent le fonctionnement hydro-morpho-sédimentaire et biogéochimique de l'estuaire, modifiant ainsi les paramètres environnementaux de l’estuaire amont jusqu’à la baie de Seine (ex. nature des fonds, courant, turbidité, salinité, température, oxygène dissous, chlorophylle-a). La modélisation de ces paramètres, ainsi que leur évolution face à différents scénarios... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00284/39480/37966.pdf |
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| Grasso, Florent; Mengual, Baptiste; Le Hir, Pierre; Walther, Régis; Verney, Romaric. |
| L'embouchure de l’estuaire de la Seine a subi de fortes altérations morphosédimentaires au cours du dernier siècle et son évolution se poursuit encore actuellement. La question du devenir du système et des habitats associés est donc posée, en tenant compte d'éventuels changements environnementaux ou climatiques. La modélisation morphosédimentaire a pour ambition de simuler le devenir de la morpho-bathymétrie, en rendant compte des couplages entre processus hydrodynamiques, transports de sédiment et évolution de la morphologie. Le projet MORPHOSEINE vise à exploiter l'outil de modélisation MARS3D CurviSeine mis en place par l’Ifremer dans le cadre des programmes Seine-Aval (SA) 4 et 5, afin de répondre à l'attente concernant l'évolution possible de... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00684/79630/82353.pdf |
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| Dubarbier, Benjamin; Castelle, Bruno; Marieu, Vincent; Michallet, Hervé; Grasso, Florent; Ruessink, Gerben. |
| The recent advances of numerical beach profile models allowed the simulation of on/offshore sandbar migrations on timescales of weeks to months with fair success. These models were systematically applied to natural, persistently evolving, beaches. In this contribution, we apply our model to small-scale laboratory experiments for which coarse and lightweight sediment is used to satisfy the laws of similitude in the flume. Such experiments can result in equilibrium beach profiles and provide detailed information on the respective role of undertow and wave nonlinearities on sediment transport and the resulting cross-shore sandbar migration. Here we first apply the coupled, wave-averaged, cross-shore waves-currents-bathymetric evolution model 1DBeach to an... |
| Tipo: Text |
Palavras-chave: Beach profile; Numerical model; Physical modelling; Equilibrium profile; Sandbar migration. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00180/29089/27503.pdf |
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| Grasso, Florent; Le Hir, Pierre; Bassoullet, Philippe. |
| Sediment transport modelling in estuarine environments, characterised by cohesive and non-cohesive sediment mixtures, has to consider a time variation of erodibility due to consolidation. Generally, validated by settling column experiments, mud consolidation is now fairly well simulated; however, numerical models still have difficulty to simulate accurately the sedimentation and consolidation of mixed sediments for a wide range of initial conditions. This is partly due to the difficulty to formulate the contribution of sand in the hindered settling regime when segregation does not clearly occur. Based on extensive settling experiments with mud-sand mixtures, the objective of this study was to improve the numerical modelling of mixed-sediment consolidation... |
| Tipo: Text |
Palavras-chave: Mud-sand mixtures; Hindered settling; Consolidation; Experiments; Numerical modelling; Segregation. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00254/36539/35168.pdf |
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| Brinkkemper, J. A.; Lanckriet, T.; Grasso, Florent; Puleo, J. A.; Ruessink, B. G.. |
| Current coastal-evolution models generally lack the ability to accurately predict bed level change in shallow (<~2 m) water, which is, at least partly, due to the preclusion of the effect of surface-induced turbulence on sand suspension and transport. As a first step to remedy this situation, we investigated the vertical structure of turbulence in the surf and swash zone using measurements collected under random shoaling and plunging waves on a steep (initially 1:15) field-scale sandy laboratory beach. Seaward of the swash zone, turbulence was measured with a vertical array of three Acoustic Doppler Velocimeters (ADVs), while in the swash zone two vertically spaced acoustic doppler velocimeter profilers (Vectrino profilers) were applied. The vertical... |
| Tipo: Text |
Palavras-chave: Turbulence; Plunging breakers; Swash; Laboratory experiment. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00277/38812/37538.pdf |
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| Grasso, Florent; Michallet, H.; Barthelemy, E.; Certain, R.. |
| Laboratory experiments on cross-shore beach morphodynamics are presented. A lightweight sediment (density rho(s) = 1.19 g cm(-3)) model is used in order to fulfill a Shields number and Rouse number scaling. This choice aims at correctly reproducing bed load transport as well as suspension dynamics. Terraces and barred beach profiles obtained in the experiments also present close similarities with profiles observed in the field. In order to question the concept of equilibrium beach profile, wave forcings conforming to a JONSWAP spectrum were imposed over long periods (up to more than a hundred hours). An average bottom evolution velocity is defined and used to determine when the profile reaches equilibrium. Usually, beach profiles are characterized... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00092/20345/17988.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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| Grasso, Florent; Michallet, H.; Barthelemy, E.. |
| The waveshape effects on sediment transport are investigated for cross-shore beach profile changes. This study is based on experiments performed in the Laboratoire des Ecoulements Geophysiques et Industriels wave flume for irregular waves. The interest of such experiments resides in presenting complex combinations of wave skewness and asymmetry in bed load, ripple, and sheet flow regimes. Net sediment transport rates on typical beach morphodynamics are analyzed in regard to wave skewness and asymmetry, undertow, and ripple occurrence. Onshore bar migration is mainly associated with onshore-directed sediment transport, whereas terrace profile and offshore bar formation correspond to offshore sediment transport. As for natural beaches, energetic (moderate)... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00092/20341/17991.pdf |
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| Lamarque, Bastien; Deflandre, Bruno; Galindo Dalto, Adriana; Schmidt, Sabine; Romero-ramirez, Alicia; Garabetian, Frédéric; Dubosq, Nicolas; Diaz, Melanie; Grasso, Florent; Sottolichio, Aldo; Bernard, Guillaume; Gillet, Hervé; Cordier, Marie-ange; Poirier, Dominique; Lebleu, Pascal; Derriennic, Hervé; Danilo, Martin; Murilo Barboza Tenório, Márcio; Grémare, Antoine. |
| The spatial distributions of (1) surface sediment characteristics (D0.5, Sediment Surface Area (SSA), Particulate Organic Carbon (POC), Chlorophyll-a (Chl-a), Phaeophytin-a (Phaeo-a), Total and Enzymatically Hydrolyzable Amino Acids (THAA, EHAA), δ13C) and (2) sediment profile image (apparent Redox Potential Discontinuity (aRPD), numbers and depths of biological traces) characteristics were quantified based on the sampling of 32 stations located within the West Gironde Mud Patch (Bay of Biscay, NE Atlantic) in view of (1) assessing the spatial structuration of a temperate river-dominated ocean margin located in a high-energy area, (2) disentangling the impacts of hydrodynamics and bottom trawling on this structuration, and (3) comparing the West Gironde... |
| Tipo: Text |
Palavras-chave: RiOMar; Surface sediment; Spatial distribution; Sedimentary organics; Bioturbation. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00681/79336/81848.pdf |
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| Grasso, Florent; Verney, Romaric; Le Hir, Pierre; Thouvenin, Benedicte; Schulz, Elisabeth; Kervella, Youenn; Fard, I. Khojasteh Pour; Lemoine, J. -p.; Dumas, Franck; Garnier, Valerie. |
| Tidal pumping, baroclinic circulation and vertical mixing are known to be the main mechanisms responsible for the estuarine turbidity maximum (ETM) formation. However, the influence of hydro-meteorological conditions on ETM dynamics is still not properly grasped and requires further investigation to be quantified. Based on a realistic 3-dimensional numerical model of the macrotidal Seine Estuary (France) that accounts for mud and sand transport processes, the objective of this study is to quantify the influence of the main forcing (river flow, tides, waves) on the ETM location and mass changes. As expected, the ETM location is strongly modulated by semidiurnal tidal cycles and fortnightly timescales with a high sensitivity to river flow variations. The ETM... |
| Tipo: Text |
Palavras-chave: Estuary; Mud; Sand; Hydrodynamics; Turbidity maximum; Waves; Measurement; Modeling. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00416/52770/53638.pdf |
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| Registros recuperados: 21 | |
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