Publications

2020

• Projection du film "Le risque de submersion, une forte vulnérabilité régionale : de la recherche scientifique à la gestion des risques
  
  • Pouzet Pierre
  • Athimon Emmanuelle
  , 2020.
• Air entrainment modeling in the SPH method: a two-phase mixture formulation with open boundaries
  
  • Fonty Thomas
  • Ferrand Martin
  • Leroy Agnès
  • Violeau Damien
  Flow, Turbulence and Combustion, Springer Verlag, 2020, 105 (4), pp.1149-1195. (10.1007/s10494-020-00165-7)
  DOI : 10.1007/s10494-020-00165-7
• Le risque de submersion, une forte vulnérabilité régionale
  
  • Quezin Eric
  • Pouzet Pierre
  • Dupont Stéphane
  • Kerguillec Riwan
  • Robin Marc
  • Maanan Mohamed
  • Athimon Emmanuelle
  • Martinet Claude
  • Brohan Manon
  • Magne Jean
  , 2020. Ce film présente un programme de recherche original sur les tempêtes historiques en Pays de la Loire. Dans le cadre des travaux menés dans l’axe "Histoire des Risques" pour l’Observatoire Régional des Risques Côtiers en Pays de la Loire, des carottes sédimentaires ont été prélevées en différents points du littoral et des cernes d’arbres ont été analysées, ces données sont croisées avec le travail des historiens et l’analyse des archives historiques pour mieux comprendre et prévenir les risques actuels.
• Equilibrium modeling of current and future beach evolution: Vougot beach, France
  
  • Chataigner Teddy
  • Yates Marissa L.
  • Dantec Nicolas Le
  • Suanez Serge S.
  • Floch France
  • Bouvard Gabin
  • Leary Matt
  • Petton Coretin
  • Cailler Nicolas
  Coastal Engineering Proceedings, 2020 (36v), pp.sediment.17. (10.9753/icce.v36v.sediment.17)
  DOI : 10.9753/icce.v36v.sediment.17
• Drafting of two passive swimmer scale models for open-water races
  
  • Bolon B
  • Pretot C
  • Clanet Christophe
  • Larrarte Frédérique
  • Carmigniani R
  Soft Matter, Royal Society of Chemistry, 2020, 16 (31), pp.7270-7273. The interaction between two passive human swimmer scale models is investigated both experimentally and numerically. The Froude number, comparing the swimming velocity to the characteristic wave velocity, is conserved in the study. The interaction is quantified for a large range of relative positions and for three speeds corresponding to cruising, average, and sprint swimming. The associated computational fluid dynamics study using OpenFoam allows us to determine the relative positions that optimize the drafting during an open-water race: just behind a lead swimmer or at the level of the hip of a neighbor, with reductions of drag of 40% and 30%, respectively. (10.1103/PhysRevFluids.00.004800)
  DOI : 10.1103/PhysRevFluids.00.004800
• Hydraulics and bridges: A French case study of monitoring of a bridge affected by scour
  
  • Larrarte Frédérique
  • Chevalier Christophe
  • Battist Louis
  • Chollet Hugues
  Flow Measurement and Instrumentation, Elsevier, 2020, 74, pp.101783. Bridges are one of the oldest types of civil engineering structures and the interaction between the transport and hydrographic networks represents a significant issue in a country such as France. Recently, various cases highlight the importance and vulnerability of civil transport works in relation to their environmental hazards, e.g. floods, and therefore the need to develop integrated observation tools and warning systems in the aim both of optimizing the management system and of increasing the knowledge on real scour processes. This paper reports on the field approach task of a research project aiming at improving continuous monitoring in order to follow the evolution of the scour processes of a given bridge or abutment. The first step has been to identify a pilot site, representative of scour vulnerability. After a report of the scour parameters to be monitored, the benchmark study and the choice of monitoring devices available on the market are detailed. Instrumentation, sensor adaptability, limitations (actual measurement ranges, ergonomics, energy supply limits ...) and in situ implementation are then presented and discussed. Finally, preliminary measurements, post-treatments and interpretation are detailed. (10.1016/j.flowmeasinst.2020.101783)
  DOI : 10.1016/j.flowmeasinst.2020.101783
• Large Eddy Simulation for flows through emerged or slightly sub-merged square obstacles
  
  • Oukacine Marina
  • Rtimi Rajae
  • Goutal Nicole
  • Larrarte Frédérique
  • Loizeau Vincent
  • Benhamadouche Sofiane
  • Proust Sébastien
  , 2020, pp.8 p.. As a result of climate change, we believe that extreme floods will become more frequent and more intense. The flows through obstacles representing an urbanized floodplain is realised in a laboratory at Re = 4766 and 8580. The purpose of the present study is first to validate a numerical model using Large Eddy Simulation (LES) against experimental data regarding the average longitudinal velocity and the secondary vortices formation. Then, additional data can be obtained and quantified. Therefore the geometrical parameters can be changed and their influence analysed and compared to the literature. A good agreement was found between simulated and experimental vertical profiles of time averaged velocity for the flow through emerged or slightly submerged obstacles. The additional simulations highlight that the flow structure is mostly driven by the transverse aspect ratio using the distance between two adjacent obstacles.
• Downstream erosion and deposition dynamics of fine suspended sediments due to dam flushing
  
  • Antoine G.
  • Camenen B.
  • Jodeau M.
  • Némery J.
  • Esteves M.
  Journal of Hydrology, Elsevier, 2020, 585 (5), pp.124763. Fine sediment dynamics downstream dams is a key issue when dealing with environmental impact of hydraulic flushing. This paper presents an analysis of six field campaigns carried out during dam flushing events (in June 2006, 2007, 2009, 2010, 2011, and 2012) in the Arc- Isere river system in the Northern French Alps. Suspended sediment concentrations (SSC) and discharges were evaluated using direct measurements or/and 1D hydraulic modelling at up to 14 locations along the 120 kilometres-long river channel. The total suspended sediment flux (SSF) is analysed along the Arc and Isere rivers for each Arc dam flushing event. Uncertainties were quantified based on a propagation method of both measurement and modelling errors. The resulting confidence interval provides elements of discussion on the significance of the sediment mass balance between two consecutive measurement sites. Whereas the discharge time-series of each flushing event is roughly the same, the quantity of fine sediments removed from the reservoirs varied from 10,000 tons in 2007 to 40,000 tons in 2006. Also, a significant erosion is observed in the river system for some events (20,000 tons in 2007) while the SSF barely varied for other events (in 2009 and 2011). This detailed data set allows to identify specific locations in the river network where deposition or erosion occurred. This dynamics is closely related to both the hydrology in the upper Isere River and the morphology of the Arc and Isere rivers, which have been affected by the 2008 and 2010 floods. (10.1016/j.jhydrol.2020.124763)
  DOI : 10.1016/j.jhydrol.2020.124763
• A new criterion for the evaluation of the velocity field for rainfall-runoff modelling using a shallow-water model
  
  • Taccone Florent
  • Antoine Germain
  • Delestre Olivier
  • Goutal Nicole
  Advances in Water Resources, Elsevier, 2020, 140, pp.103581. The aim of this work is to evaluate the accuracy of physically based models using the 2D Shallow Water Equations (SWE) for the simulation of rain-induced runoff. A key expectation of these models is to be able to reproduce properly both hydrograph at the outlet of the watershed and the associated velocity field within the spatial domain for a given rain event. However, this ability can be very challenging in mountainous environments, which include heterogeneous and high values of bottom slope and transient rain inputs. In this paper, we focused on both the error due to the numerical resolution of the SWE for low water depths runoff on steep slopes and that due to the physical representation of friction on the bottom for various water depth to roughness height ratios. Four test cases have been used, at different scales, to evaluate the model in comparison with experimental data. The first test case (from [Kirstetter et al., 2015]) was a rain induced flow in a straight channel. It allows to evaluate the error made for the chosen numerical resolution of the SWE and its impact on the velocity distribution in the domain (metric scale). A criterion defining an acceptable numerical error has been proposed. A second test case (from [Cea et al., 2014]), has been chosen for being also metric scaled and in the right range of the numerical error criterion. It allowed to evaluate the ability of a new friction law (adapted from [Lawrence, 1997]) to represent the measured velocity field in several inundation regimes at the metric scale. The third test case was a 40 m 2 real plot studied by [Tatard et al., 2008]. On this test case, measured velocities have been compared with the simulated ones. Thanks to an infiltration source term added to the mass conservation equation, hydrographs at the outlet of the plot have been well reproduced, as well as the main part (including the highest values) of the measured velocities. In particular, the velocities are well represented when the criterion given in the first test case is satisfied. Finally, the model is applied to a real watershed with an area of 1 km 2 on which hydrographs at the outlet have been successfully reproduced for two extreme rainy events [Le Bouteiller et al., 2015]. It appeared that both physical and numerical error were low in the hydrographic network and that the local velocities are correctly reproduced there, unlike in the hillslopes where the velocities are not well reproduced even if the mass fluxes are correct. (10.1016/j.advwatres.2020.103581)
  DOI : 10.1016/j.advwatres.2020.103581
• Bar pattern and sediment sorting in a channel contraction/expansion area: Application to the Loire River at Bréhémont (France)
  
  • Cordier Florian
  • Tassi Pablo
  • Claude Nicolas
  • Crosato Alessandra
  • Rodrigues Stéphane
  • Pham van Bang Damien
  Advances in Water Resources, Elsevier, 2020, 140, pp.103580. (10.1016/j.advwatres.2020.103580)
  DOI : 10.1016/j.advwatres.2020.103580
• Tidal Patterns and Sediment Dynamics in a Hypertidal Estuary Influenced by a Tidal Power Station
  
  • Rtimi Rajae
  • Sottolichio Aldo
  • Tassi Pablo
  Journal of Coastal Research, Coastal Education and Research Foundation, 2020, 95 (sp1), pp.1520. (10.2112/SI95-293.1)
  DOI : 10.2112/SI95-293.1
• Coordination changes in front-crawl swimming
  
  • Carmigniani R.
  • Seifert L.
  • Chollet D.
  • Clanet C.
  Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Royal Society, The, 2020, 476 (2237), pp.20200071. (10.1098/rspa.2020.0071)
  DOI : 10.1098/rspa.2020.0071
• Morphodynamics of alternate bars in the presence of riparian vegetation
  
  • Jourdain Camille
  • Claude Nicolas
  • Tassi Pablo
  • Cordier Florian
  • Antoine Germain
  Earth Surface Processes and Landforms, Wiley, 2020, 45 (5), pp.1100-1122. Abstract Alpine gravel‐bed rivers are dynamic systems that have been subjected to many anthropic alterations in the past centuries. Riparian vegetation development on previously bare sediment bedforms has been a common adjustment, raising important management issues in terms of flood risks and biodiversity. Many of these rivers are also channelized, and as a result present a pattern of alternate bars. Considering recent advances in numerical biomorphodynamic modeling, this study aims at exploring numerically the morphodynamics of alternate bars in the presence of riparian vegetation. To this end, a dynamic vegetation module has been implemented on top of an existing morphodynamic model, accounting for ecological processes of seed dispersal, seedling recruitment, growth, and mortality. Numerical simulations have been performed on a simplified reach of a gravel‐bed river with free migrating alternate bars at initial state. In this work 96 scenarios have been simulated, each representing 50 years of channel evolution, with different flood regimes characterized by various peak discharges and flood durations. Yearly peak discharge variability is explicitly modeled in 48 scenarios. Model outcomes present two possible equilibrium biomorphodynamic behaviors: stationary vegetated bars, or free migrating bars in the case of frequent vegetation removal during floods. This binary behavior holds true when the stochasticity of annual peak discharges is represented, and for a wide range of parameter values included in vegetation dynamic modeling. Transient mobility of vegetated bars is observed in specific configurations where large sediment deposits deflect the flow field, eroding bar heads. Modeled bar wavelengths are in the range of values predicted for free bars by linear bar theory, and remain far from the theoretical values of hybrid, steady bars. The shift from unvegetated migrating bars to steady vegetated bars seems to show that in these simulations vegetation constitutes a hydraulic forcing, leading to a shift from free bars to forced bars, with a final configuration largely inherited from the initial state. © 2019 John Wiley & Sons, Ltd. (10.1002/esp.4776)
  DOI : 10.1002/esp.4776
• Quantification d'incertitudes et assimilation de données pour la modélisation hydrodynamique bidimensionnelle : application au modèle de prévision des hautes eaux de l’estuaire de la Gironde
  
  • Laborie Vanessya
  , 2020. Cette thèse s'inscrit dans le cadre du développement de techniques d'assimilation de données dans les codes de calcul bidimensionnels d'hydraulique à surface libre et, plus particulièrement, de l'évaluation des possibilités d'amélioration de la prévision des hautes eaux sur l'estuaire de la Gironde par le développement et l'utilisation de ces méthodes. Les caractéristiques principales de ces travaux concernent le caractère instationnaire de l'hydrodynamique, liée à la fois à la propagation de la marée et à l'événement hydrométéorologique considéré, et la corrélation entre les observations des différentes stations de mesures disponibles. Les travaux réalisés pendant la première partie de la thèse ont porté sur la proposition d'une méthodologie de traitement des incertitudes par analyse globale de sensibilité par décomposition de variance pour un code d'hydrodynamique alimenté par des variables fonctionnelles. Cette méthodologie a permis la classification des sources d'incertitudes à partir d'un échantillon des réalisations du modèle Telemac2D de prévision des hautes eaux de l'estuaire de la Gironde, dans le but de hiérarchiser l'influence des forçages et des paramètres du modèle. Dans un second temps, en lien avec les résultats de l'étude précédente, une méthodologie a été proposée pour développer une chaîne de simulation intégrant le code de calcul étudié et une méthode ensembliste d'assimilation de données fondée sur le Filtre de Kalman d'Ensemble, dans l'objectif de réduire les incertitudes du modèle liées à ses forçages fonctionnels et à sa paramétrisation par l'utilisation d'observations. Dans un premier temps, cette méthodologie a été appliquée au modèle Telemac2D de l'estuaire de la Gironde sous la forme d'un protocole d'expériences jumelles dont l'objectif est, d'une part, de procéder à sa validation et, d'autre part, de déterminer de manière optimale le vecteur de contrôle, le réseau de mesures et les paramètres liés à la méthodologie proposée. Les gains de la méthodologie proposée sont ensuite évalués en utilisant les observations disponibles pour plusieurs événements réels
• Simulating wave overtopping on a complex coastal structure using SPH
  
  • Mokos Athanasios
  • Carmigniani Rémi
  • Leroy Agnès
  • Violeau Damien
  Journal of Applied Water Engineering and Research, Taylor & Francis Online, 2020, 8 (1), pp.55-65. (10.1080/23249676.2020.1719221)
  DOI : 10.1080/23249676.2020.1719221
• Simulating wave overtopping on a complex coastal structure using SPH
  
  • Mokos Athanasios
  • Carmigniani Rémi
  • Leroy Agnès
  • Violeau Damien
  Journal of Applied Water Engineering and Research, Taylor & Francis Online, 2020, 8 (1), pp.55-65. (10.1080/23249676.2020.1719221)
  DOI : 10.1080/23249676.2020.1719221
• Energy Transfers and Reflection of Infragravity Waves at a Dissipative Beach Under Storm Waves
  
  • Bertin Xavier B
  • Martins Kévin
  • de Bakker Anouk
  • Chataigner Teddy
  • Guérin Thomas
  • Coulombier Thibault
  • Viron Olivier
  Journal of Geophysical Research. Oceans, Wiley-Blackwell, 2020, 125 (5), pp.e2019JC015714. This study presents unpublished field observations of infragravity waves, collected at the dissipative beach of Saint‐Trojan (Oléron Island, France) during the storm Kurt (3 February 2017), characterized by incident short waves of significant heights reaching 9.5 m and peak periods reaching 22 s. Data analysis reveals the development of exceptionally large infragravity waves, with significant heights reaching 1.85 m close to shore. Field observations are complemented by numerical modeling with XBeach, which well reproduces the development of such infragravity waves. Model results reveal that infragravity waves were generated mainly through the bound wave mechanism, enhanced by the development of a phase lag with the shortwave energy envelope. Spectral analysis of the free surface elevation shows the generation of superharmonic and subharmonic infragravity waves, the latter dominating the free surface elevation variance close to shore. Modeling results suggest that subharmonic infragravity waves result, at least partly, from infragravity‐wave merging, promoted by the combination of free and bound infragravity waves propagating across a several kilometer‐wide surf zone. Due to the steeper slope of the upper part of the beach profile, observed and modeled reflection coefficients under moderate‐energy show a strong tidal modulation, with a weak reflection at low tide (R2<0.2) and a full reflection at high tide (R2∼1.0). Under storm waves, the observed reflection coefficients remain unusually high for a dissipative beach (R2∼0.5−1.0), which is explained by the development of subharmonic infragravity waves with frequencies around 0.005 Hz, too long to suffer a substantial dissipation. (10.1029/2019JC015714)
  DOI : 10.1029/2019JC015714
• Decadal-scale morphological evolution of a muddy open coast
  
  • Orseau Sylvain
  • Zorrilla Noelia Abascal
  • Huybrechts Nicolas
  • Lesourd Sandric
  • Gardel Antoine
  Marine Geology, Elsevier, 2020, 420, pp.106048. Analysis of the long-term morphological evolution of a muddy open-coastSediment transport suggests a growth of mudbanks migrating along the coast.Cross-shore exchange of sediment is equally significant as longshore transport.Mudbank and shoreline erosion/accretion trends are reversed. (10.1016/j.margeo.2019.106048)
  DOI : 10.1016/j.margeo.2019.106048
• Two-dimensional modeling of fine sediment transport with mixed sediment and consolidation: Application to the Gironde Estuary, France
  
  • Orseau Sylvain
  • Huybrechts Nicolas
  • Tassi Pablo
  • Pham van Bang Damien
  • Klein Fabrice
  International Journal of Sediment Research, Elsevier, 2020. In order to optimize ship navigation in the macrotidal Gironde Estuary, a recent project funded by the port of Bordeaux aims at better understand and forecast hydrodynamic and fine sediment transport within the estuary. In the framework of this project, a two-dimensional hydro-sedimentary model is built. The model includes hydrodynamic forcings, mixed-sediment transport, and consolidation processes. The harmonic analysis of the astronomical tides reveals a strong distortion of the tidal wave inducing the growth of overtide constituents and the non-significant effect of tide-surge interactions in annual-scale prediction. Depending on hydrological conditions, river discharge can considerably alter the model accuracy due to the migration of the turbidity maximum zone modifying the bottom roughness. Comparison with measurements shows the ability of the model to reproduce suspended-sediment concentrations in the central Estuary. Sensitivity of the model to sediment features has also been discussed in regard of suspended-sediment concentrations and fluid mud deposits. The model will be further coupled with ship squat predictions and a morphodynamic model.p { margin-bottom: 0.25 cm; line-height: 115%; } (10.1016/j.ijsrc.2019.12.005)
  DOI : 10.1016/j.ijsrc.2019.12.005