Marissa YATES

Chercheur LHSV

Joined the laboratory in 2011

Education

HDR at Université Paris-Est, Margne-La-Vallée, France, 2020
PhD in Coastal Oceanography, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA, 2009
B.S. Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, 2003

Fields of interest

Coastal oceanography, nonlinear wave propagation, wave breaking, coastal morphodynamics, littoral evolution

Research projects

Modeling nonlinear and dispersive wave propagation, modeling wave breaking in fully nonlinear potential flow models
Experimental measurements of wave breaking statistics and wave loads on structures
Equilibrium modeling of shoreline evolution
Estimating the impacts of climate change on shoreline evolution

Teaching

Ecole des Ponts ParisTech (3rd year students):
- Coastal and Port Project
ENSTA ParisTech (3rd year students, class shared with the WAPE and STEEM IP-Paris Masters):
- Sea States, Wave Propagation, and Ocean Wave Energy
- Coastal Engineering, Anchors, and Cables

Students and postdocs

Sunil Mohanlal (thesis co-advisor), 2020-2023
Marc Igigabel (thesis co-advisor), 2022
Teddy Chataigner (thesis director, co-advised + post-doc co-advisor), 2018-2021, 2022
Cécile Raoult (thesis co-advisor), 2014-2017
Mathieu Gervais (post-doc co-advisor), 2015
Christos Papoutsellis (post-doc co-advisor), 2017
Bruno Simon (post-doc co-advisor, at the l'IRPHE/ECM), 2018-2019
Philip Balitsky (post-doc co-advisor Cerema/FEM Projet ANR-FEM DiMe), 2020-2021

Publications

L'hydrodynamique des vagues du large jusqu'à la côte : modélisation et impacts
- Benoit Michel
- Harris Jeffrey
- Yates Marissa
Transitions. Les nouvelles Annales des Ponts et Chaussées, École des Ponts ParisTech et Presses des Ponts , 2025 (5), pp.44-48 .
MODELLING SHORELINE DYNAMICS IN COMPLEX MACROTIDAL ENVIRONMENTS USING NEURAL NETWORKS
- Mingorance Gabriel
- Sénéchal Nadia
- Bertin Stéphane
- Floc'H France
- Suanez Serge
- Yates Marissa L.
, 2025 . <div><p>The aim of this work is to test an artificial intelligence approach with basic hydrodynamic and morphological variables, in order to assess the effectiveness of such methods in modelling complex beach dynamics. A simple feedforward neural network is used to evaluate the impact of selected variables on the prediction of the dynamics of specific shoreline isocontour proxies extracted from beach profiles, and to build a predictive model that could simulate the position of the proxies. The model was trained on datasets from two sites from the French coastal monitoring program DYNALIT, Porsmilin and Vougot beaches, and their profile measurements, water levels and wave measurements over 20 years. These two sites were selected due to differences in their morphology and hydrodynamics, as a means to assess the performance of neural networks over a larger variety of situations. A range of temporalities encompassing 3 days, 7 days, 14 days, and 30 days of selected hydrodynamic and morphological variables were used to study the impact time scales can have on modelled shoreline positions. The shoreline proxies used for Porsmilin and Vougot beaches correspond respectively to the berm and the contact between the dune toe and the upper beach, which can be assessed and followed along each beach profile. The shallow feedforward network included 1 hidden layer and 5 nodes, and was ran 50 times in order to assess the models' performance. The models were generally successful, with a blind shoreline prediction R of 0.88 in Porsmilin and 0.72 in Vougot. This artificial neural network (ANN) approach showed all-around better performance than previous beach equilibrium models, which is very encouraging regarding the prediction of future beach morphodynamics and the use of Machine Learning algorithms therein.</p></div>
Observation morphodynamique à long terme pour l'étude des évènements extrêmes dans l'évolution et la projection morphologiques des côtes
- Suanez Serge
- Stéphan Pierre
- Hénaff Alain
- Letortu Pauline
- Rouan Mathias
- David Laurence
- Pierson Julie
- Floc'H France
- Bertin Stéphane
- Le Dantec Nicolas
- Jaud Marion
- Ammann Jérôme
- Augereau Emmanuel
- Prunier Christophe
- Delacourt Christophe
- Dodet Guillaume
- Accensi Mickaël
- Ardhuin Fabrice
- André Gaël
- Leballeur Laurent
- Yates Marissa L.
, 2024 . Depuis plus de 20 ans, des suivis topomorphologiques sont réalisés sur plusieurs sites littoraux de Bretagne caractérisés par des morphologies très variées comme des systèmes de plage/dune, des cordons de galets, ou des falaises rocheuses. Ces observations ont été facilitées par le développement et la généralisation de techniques de mesures pertinentes dès les années 2000 (GPS, TLS, drone, LiDAR, imageries satellitaires, etc.). Pour chacune de ces morphologies, le choix d’un indicateur permettant d’enregistrer les changements morphologiques liés à la variation des conditions météo-marines (évènements extrêmes vs temps calme) est observé à des fréquences mensuelle à annuelle. La compilation de ces données permet de proposer un inventaire des évènements extrêmes ayant eu un impact significatif sur la morphologie des côtes en terme d’érosion et/ou de submersion au cours des deux dernières décennies. Ces données permettent également d’estimer les périodes de retour de ces épisodes morphogènes et/ou de faire des projections à plus ou moins long terme de l’évolution du littoral, notamment pour l’érosion.
Using 17 years of beach/dune profile monitoring to characterize morphological dynamics related to significant extreme water level events in North Brittany (France)
- Suanez Serge
- Yates Marissa L.
- Floc'H France
- Accensi Mickaël
Geomorphology, Elsevier , 2023, 433, pp.108709 . Long-term in situ monitoring of beach morphology is crucial for understanding the physical processes of coastal changes and defining the strategies of sustainable coastal management. Monthly surveys based on the beach/dune profile measurements started in July 2004 along six transects distributed along the Vougot beach (North Brittany). The analysis of these data from 2004 to 2021 shows that the eastern part of the beach has experienced chronic erosion during the 17-year period. This erosion has led to a lowering of the beach profile by about –1 to –1.5 m, and has resulted in the removal of beach sand such that waves now impact the underlying Holocene peat and Pleistocene silts or pebbles during most of the year. Conversely, the western part of the beach has accreted. Vougot beach is thus experiencing a rotation phenomenon characterized by a longshore sediment flux from the east to the west. The multidecadal evolution of the beach/dune system is punctuated by events causing significant retreat of the dune, especially when storm waves are combined with high spring tide levels. The event causing the most significant morphological changes was associated with extreme water levels (EWL) up to 9.6 m (i.e., Anne storm in February 2014), causing 14.5 m3 l.m-1 of dune sediment loss. The analysis of 17 years of hydrodynamic conditions (waves and water levels) indicates an increase in the wave runup height (+65%) and EWL (+17%). Calculation of the water level that exceeds the dune toe position (Δzexceedance) helps to further quantify the impacts of storm events on dune volume changes. The Anne storm had an EWL with a return period of approximately 13 years, but when combined with the dune toe position, showed the largest dune toe exceedance value (3.0 m), corresponding to a return period of approximately 21 years. Lastly, the events causing the most significant dune erosion during this 17-year study period have also caused shoreline erosion and/or landward barrier migration at many other sites in North Brittany, showing the broader scale impacts of observations at individual study sites. (10.1016/j.geomorph.2023.108709)
DOI : 10.1016/j.geomorph.2023.108709
Morphodynamic Evolution and Sustainable Development of Coastal Systems
- Dissanayake Pushpa
- Brown Jennifer
- Yates Marissa L.
Journal of Marine Science and Engineering, MDPI , 2022, 10 (5), pp.647 . Coastal systems are highly dynamic morphological environments due to erosion and sedimentation at different spatio-temporal scales as a result of natural forcing [...] (10.3390/jmse10050647)
DOI : 10.3390/jmse10050647
Sensitivity of a one-line longshore shoreline change model to the mean wave direction
- Chataigner T.
- Yates Marissa L.
- Le Dantec N.
- Harley M.D.
- Splinter K.D.
- Goutal N.
Coastal Engineering, Elsevier , 2022, 172, pp.104025 . (10.1016/j.coastaleng.2021.104025)
DOI : 10.1016/j.coastaleng.2021.104025
Time-scales of a dune-beach system and implications for shoreline modelling
- Montaño Jennifer
- Coco Giovanni
- Chataigner Teddy
- Yates Marissa L.
- Le Dantec Nicolas
- Suanez Serge S.
- Gagigal Laura
- Floc'H France
- Townend Ian
Journal of Geophysical Research: Earth Surface, American Geophysical Union/Wiley , 2021, 126 (11), pp.e2021JF006169 . Understanding the interactions between dune systems and beaches is critical to determining the short-term shoreline response and the long-term resilience. In this study, almost 15 years of monthly beach/dune measurements were analysed for three diﬀerent proﬁles at Vougot Beach, France to understand and predict shoreline changes from intra- to multi-annual time- scales. Four migration modes: advance/retreat (translation modes) and steepening/flattening (rotation modes) were identified through a centroid analysis. The analysis showed that translation and rotation can occur simultaneously, with long-term trends of beach retreat and profile steepening (lower beach retreating and upper beach advancing), which was interrupted by two energetic wave events causing profile ﬂattening (lower beach advancing and upper beach retreating). These two observations are evidence of how the sediment contribution resulting from the dune erosion events temporarily caused a large advance in the shoreline position. A recent modelling approach that accounts for diﬀerent time-scales is applied to predict the shoreline changes, showing signiﬁcant improvements in comparison to a traditional shoreline equilibrium model when time-scales related with the dune erosion and recovery are considered. The results showed that the dune system aﬀects the beach proﬁle evolution both spatially, with diﬀerent impacts at diﬀerent elevations along the cross-shore proﬁle, and temporally, by periodically redistributing the sediment in the system. (10.1029/2021JF006169)
DOI : 10.1029/2021JF006169
Climate change impacts on coastal wave dynamics at Vougot Beach, France
- Dissayanake Pushpa
- Yates Marissa L.
- Suanez Serge S.
- Floc'H France
- Krämer Knut
Journal of Marine Science and Engineering, MDPI , 2021, 9 (9), pp.1009 . Wave dynamics contribute significantly to coastal hazards and are thus investigated at Vougot Beach by simulating both historical and projected future waves considering climate change impacts. The historical period includes a major storm event. This period is projected to the future using three globally averaged sea level rise (SLR) scenarios for 2100, and combined SLR and wave climate scenarios for A1B, A2 and B1 emissions paths of the IPCC. The B1 wave climate predicts an increase in the occurrence of storm events. The simulated waves in all scenarios show larger relative changes at the beach than in the nearshore area. The maximum increase of wave energy for the combined SLR and wave scenarios is 95%, while only 50% for the SLR-only scenarios. The effective bed shear stress from waves and currents shows different spatial variability than that of the wave height, emphasizing the importance of interactions between nearshore waves and currents. Increases in the effective bed shear stress (combined scenarios: up to 190%, and SLR-only scenarios: 35%) indicate that the changes in waves and currents will likely have significant impacts on the nearshore sediment transport. This work emphasizes that combined SLR and future wave climate scenarios need to be used to evaluate future changes in local hydrodynamics and their impacts. These results provide preliminary insights into potential future wave dynamics at Vougot Beach under different climate change scenarios. Further studies are necessary to generalize the results by investigating the wave dynamics during different storm periods and to evaluate potential changes in sediment transport and morphological evolution due to climate change. (10.3390/jmse9091009)
DOI : 10.3390/jmse9091009
A new definition of the kinematic breaking onset criterion validated with solitary and quasi-regular waves in shallow water
- Varing Audrey
- Filipot Jean-Francois
- Grilli Stephan
- Duarte Rui
- Roeber Volker
- Yates Marissa L.
Coastal Engineering, Elsevier , 2021, 164, pp.103755 . A large body of work has been devoted to the accurate detection and simulation of wave breaking in coastal areas. It is a key process for a wide range of engineering activities and environmental issues. This has motivated the development of a variety of breaking onset criteria, such as kinematic criteria based on a maximum value (usually unity) of the ratio u c /c, of the horizontal particle velocity at the wave crest u c to its phase velocity c, both taken in the direction of wave propagation. Here, we investigate numerically the validity of this criterion in capturing breaking onset for solitary and quasi-regular two-dimensional shallow water waves using the Fully Nonlinear Potential Flow (FNPF) model by Grilli and Subramanya (1996). With this model, the propagation up to overturning of solitary waves over plane slopes, and solitary and quasiregular waves over a submerged bar, both initially specified as numerically exact FNPF waves, is simulated. In all cases, waves break as spilling or plunging breakers, initiated by the formation of a breaker jet near the wave crest. Results show that the location of the maximum fluid velocity u m on the free surface closely coincides with the location where the overturning jet is initiated. Based on this, a new breaking onset criterion is proposed as u m /c 1, which is shown to be more universal for accurately detecting wave breaking initiation than existing criteria based on the crest velocity. (10.1016/j.coastaleng.2020.103755)
DOI : 10.1016/j.coastaleng.2020.103755
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
Comparing methods of modeling depth-induced breaking of irregular waves with a fully nonlinear potential flow approach
- Simon Bruno
- Papoutsellis Christos
- Benoit Michel
- Yates Marissa L.
Journal of Ocean Engineering and Marine Energy, Springer , 2019 . The modeling of wave breaking dissipation in coastal areas is investigated with a fully nonlinear and dispersive wave model. The wave propagation model is based on potential flow theory, which initially assumes non-overturning waves. Including the impacts of wave breaking dissipation is however possible by implementing a wave breaking initiation criterion and dissipation mechanism. Three criteria from the literature, including a geometric, kinematic, and dynamic-type criterion, are tested to determine the optimal criterion predicting the onset of wave breaking. Three wave breaking energy dissipation methods are also tested: the first two are based on the analogy of a breaking wave with a hydraulic jump, and the third one applies an eddy viscosity dissipative term. Numerical simulations are performed using combinations of the three breaking onset criteria and three dissipation methods. The simulation results are compared to observations from four laboratory experiments of regular and irregular waves breaking over a submerged bar, irregular waves breaking on a beach, and irregular waves breaking over a submerged slope. The different breaking approaches provide similar results after proper calibration. The wave transformation observed in the experiments is reproduced well, with better results for the case of regular waves than irregular waves. Moreover, the wave statistics and wave spectra are predicted well in general, and in particular for regular waves. Some differences are observed for irregular wave cases, in particular in the low-frequency range. This is attributed to incomplete absorption of the long waves in the numerical model. Otherwise, the wave spectra in the range [0.5fp, 5fp] are reproduced well, before, inside, and after the breaking zone for the three irregular wave experiments. (10.1007/s40722-019-00154-7)
DOI : 10.1007/s40722-019-00154-7
Modelling of depth-induced wave breaking in a fully nonlinear free-surface potential flow model
- Papoutsellis Christos
- Yates Marissa L.
- Simon Bruno
- Benoit Michel
Coastal Engineering, Elsevier , 2019, 154, pp.103579 . (10.1016/j.coastaleng.2019.103579)
DOI : 10.1016/j.coastaleng.2019.103579
Development and validation of a 3D RBF-spectral model for coastal wave simulation
- Raoult Cécile
- Benoit Michel
- Yates Marissa L.
Journal of Computational Physics, Elsevier , 2019, 378, pp.278-302 . With the objective of simulating wave propagation in the nearshore zone for engineering-scale applications, a two dimensional (2DV) model based on the Euler-Zakharov equations (Yates and Benoit, 2015; Raoult et al., 2016) is extended to three dimensions (3D). To maintain the flexibility of the approach with the goal of applying the model to irregularly shaped domains, the horizontal plane is discretized with scattered nodes. The horizontal derivatives are then estimated using the Radial Basis Function-Finite Difference (RBF-FD) method, while a spectral approach is used in the vertical dimension. A sensitivity analysis examined the robustness of the RBF-FD approach as a function of RBF parameters when estimating the derivatives of a representative function. For a targeted stencil size between 20 and 30 nodes, Piecewise-Smooth (PS) polyharmonic spline (PHS) functions are recommended, avoiding the use of Infinitely-Smooth (IS) RBFs, which are less appropriate for the desired applications because of their dependence on a shape parameter. Comparisons of simulation results to observations from two wave basin experiments show that nonlinear effects induced by complex bottom bathymetries (10.1016/j.jcp.2018.11.002)
DOI : 10.1016/j.jcp.2018.11.002
Coastal Wave Hydrodynamics and Morphological Evolution
- Yates Marissa L.
, 2019 . Ce manuscrit présente un résumé de mes travaux de recherche qui sont focalisés sur deux thèmes principaux : l’évolution morphologique des plages et l’hydrodynamique de vagues en zone côtière. Ces deux thèmes sont fortement liés, avec l’objectif commun d’améliorer, à la fois la connaissance des processus physiques qui contrôlent la dynamique en zone côtière, et aussi les modèles numériques capables de reproduire l’hydrodynamique et l’évolution morphologique dans cet environnement complexe. Le premier chapitre présente succinctement ces deux thèmes, mes projets de recherche, les collaborations que j’ai développées et l’évolution de mes travaux de recherche pendant les 10 dernières années depuis la n ma thèse. Pendant cette période, j’ai suivi une gamme d’approches diérentes pour aborder ces thèmes, allant de l’analyse des observations in situ et des expériences en laboratoire, à la modélisation empirique et numérique des processus observés. Ces approches complémentaires m’ont d’abord permis d’étudier les processus physiques qui contrôlent la dynamique en zone côtière à plusieurs échelles d’espace et de temps pour développer une vision globale de cet environnement complexe. Ces travaux ont de plus contribué à mon deuxième objectif, à savoir le développement des modèles empiriques et numériques pour une variété d’applications, allant de l’évaluation des risques côtiers et l’estimation de la ressource des énergies marines renouvelables, au dimensionnement et à la gestion des structures marines et côtières. Le deuxième chapitre est dédié au thème de la morphodynamique en zone côtière, avec deux grands axes de travail : (1) l’analyse de l’évolution morphologique des plages, basée sur des observations morphologiques de plusieurs sites d’étude et sur des mesures expérimentales eectuées en laboratoire, pour améliorer la compréhension des variations spatiales et temporelles observées, et (2) la modélisation empirique et numérique de l’évolution des prols de plage, validés avec les observations, pour améliorer les outils de prédiction. Ses travaux m’ont permis d’identier des questions fondamentales qui continuent de structurer mes thèmes de recherche, en particulier une amélioration de la compréhension des processus d’érosion et d’accrétion, et notamment des variations en espace et en temps à une variété d’échelles. Ces connaissances me permettent de valider des modèles numériques basés sur des processus physiques et de les appliquer aux échelles spatiales locales et aux échelles temporelles des événements, mais aussi de proposer des modèles simpliés, de type empirique, applicables aux échelles spatiales d’une plage ou d’un secteur du littoral et aux échelles temporelles des saisons, des années, des décennies. Mes travaux en cours explorent diérents axes d’amélioration de ces types de modélisation, notamment pour améliorer la prise en compte des processus physiques dans un modèle empirique d’équilibre, incluant le transport longshore, les interactions entre les vagues et le niveau de l’eau et les impacts du changement climatique.
FULLY NONLINEAR MODELING OF NEARSHORE WAVE PROPAGATION INCLUDING THE EFFECTS OF WAVE BREAKING
- Papoutsellis Christos
- Yates Marissa L.
- Simon Bruno
- Benoit Michel
, 2018, 1 (36) . INTRODUCTION Nearshore wave modeling over spatial scales of several kilometers requires balancing the fine-scale modeling of physical processes with the model's accuracy and efficiency. In this work, a fully nonlinear potential flow model is proposed as a compromise between simplified linear, weakly nonlinear or weakly dispersive models and direct CFD approaches. (10.9753/icce.v36.waves.78)
DOI : 10.9753/icce.v36.waves.78
FULLY NONLINEAR MODELING OF NEARSHORE WAVE PROPAGATION INCLUDING THE EFFECTS OF WAVE BREAKING
- Papoutsellis Christos E
- Yates Marissa L.
- Simon Bruno
- Benoit Michel
, 2018, 1 (36), pp.78 . INTRODUCTION Nearshore wave modeling over spatial scales of several kilometers requires balancing the fine-scale modeling of physical processes with the model's accuracy and efficiency. In this work, a fully nonlinear potential flow model is proposed as a compromise between simplified linear, weakly nonlinear or weakly dispersive models and direct CFD approaches. (10.9753/icce.v36.waves.78)
DOI : 10.9753/icce.v36.waves.78
Développement d’un modèle numérique non-linéaire et dispersif pour la propagation des vagues en zone côtière
- Raoult Cécile
- Benoit Michel
- Yates Marissa L.
Revue Paralia, Editions Paralia CFL , 2018, 11, pp.n01.1 - n01.14 . (10.5150/revue-paralia.2018.n01)
DOI : 10.5150/revue-paralia.2018.n01
Analysis of the linear version of a highly dispersive potential water wave model using a spectral approach in the vertical
- Benoit Michel
- Raoult Cécile
- Yates Marissa L.
Wave Motion, Elsevier , 2017, 74, pp.159 - 181 . h i g h l i g h t s • Highly dispersive potential flow model for water wave propagation. • Linear dispersion relation accurate in very deep water conditions (kh up to 100). • Accurate prediction of wave kinematics (orbital velocities) in deep water. • Validation of linear shoaling properties of the model. • Good prediction of reflected and transmitted waves on a Roseau-type bottom profile. a b s t r a c t The properties and accuracy of the linearized version of the fully dispersive and nonlinear wave model developed in Yates and Benoit (2015) and Raoult et al. (2016) are analyzed for both flat and variable bottom bathymetries. This model considers only a single layer of fluid and uses a basis of orthogonal Chebyshev polynomials to project the vertical structure of the potential. This approach results in an exponential convergence rate with the maximum degree of the Chebyshev polynomial, denoted N T , while only first-and second-order derivatives in space need to be evaluated. For the constant water depth case, the linear dispersion relation of the model is derived analytically, and expressions are established for N T ranging from 2 to 15. The analysis shows a rapid increase in accuracy in the deep water range with increasing N T. For instance, the relative error in the calculated wave celerity (in comparison with Stokes' analytical solution) remains smaller than 2.5% for deep water cases with kh up to 100 using N T ≥ 9 (k and h are the representative wavenumber and water depth, respectively). The wave kinematics, vertical profiles of the horizontal and vertical orbital velocities, converge to the Stokes profiles for kh up to 60 when using a sufficiently high value of N T. The vertically-averaged relative errors of the horizontal and vertical velocities remain below 6% and 3%, respectively, for kh up to 60 when using N T ≥ 11. The presented model shows better dispersive properties in deep water than several high-order Boussinesq-type models. For variable bottom bathymetries, the shoaling properties of the model are studied numerically, exhibiting good agreement with results from Stokes linear theory in the case of mild bottom slopes, using a sufficiently high value of N T with respect to the offshore relative water depth. For an offshore water depth of kh = 10 (i.e. more than 3 times the deep water limit), accurate wave heights in shallow water (kh = 0.25) are obtained with N T = 6 (or higher). Finally, the linear version of the model is validated with comparisons to analytical solutions of the reflection and transmission coefficients of regular waves over Roseau-type bathymetric profiles. Two bottom profiles are considered, including one with a steep slope, whose maximum value reaches about 1:0.7 (i.e. an angle of about 54.9 deg.). Using N T = 7, small differences (<0.4%) with the analytical solution are observed for the four considered cases, confirming the ability of the linear model to represent accurately the effects of steep bottom gradients on wave propagation dynamics. (10.1016/j.wavemoti.2017.07.002)
DOI : 10.1016/j.wavemoti.2017.07.002
Equilibrium modeling of the Beach Profile on a Macrotidal Embayed Beach
- Lemos Clara
- Floc'H France
- Yates Marissa L.
- Le Dantec Nicolas
- Marieu Vincent
- Hamon Klervi
- Cuq Véronique
- Suanez Serge S.
- Delacourt Christophe
, 2017 (No. 057), pp.pp. 760-771 . Predicting the pluriannual variability of shoreline position in response to hydrodynamic forcing (waves and tides) is of primordial interest scientists, engineers, and beach managers. 11-year time series of monthly profile beach survey and hourly incident wave conditions are analyzed on a macrotidal sandy embayed beach in Brittany (France). An equilibrium model is applied to study the variation of the beach profile position over the whole intertidal zone as a function of the energy wave, wave power and water level. The predictive ability of the equilibrium model is around 60% in the upper intertidal zone but decreases with decreasing elevation in the lower intertidal zone. The predicted result on the lower part taking into account of the still water level is not improved, but the erosion and accretion parameters are more reliable, according to the physical processes and could be compared to other study sites.
Validation of a fully nonlinear and dispersive wave model with laboratory non-breaking experiments
- Raoult Cécile
- Benoit Michel
- Yates Marissa L.
Coastal Engineering, Elsevier , 2016, 114, pp.194 - 207 . With the objective of modeling coastal wave dynamics taking into account nonlinear and dispersive effects, a highly accurate nonlinear potential flow model was developed. The model is based on the time evolution of two surface quantities: the free surface position and the free surface velocity potential. A spectral approach is used to resolve vertically the velocity potential in the domain, by decomposing the potential using an orthogonal basis of Cheby-shev polynomials. With this approach, a wide range of relative water depths can be simulated, as demonstrated here with the propagation of nonlinear regular waves over a flat bottom with kh = 2π and 4π (where k is the wave number and h the water depth). The model is then validated by comparing the simulation results to experimental data for four non-breaking wave test cases: (1) nonlinear dynamics of a wave train generated by a piston-type wavemaker in constant water depth, (2) shoaling of a regular wave train on beach with constant slope up to the breaking point, (3) propagation of regular waves over a submerged bar, and (4) propagation of nonlinear irregular waves over a barred beach. The test cases show the ability of the model to reproduce well nonlinear wave interactions and the dynamics of higher-order bound and free harmonics. The simulation results agree well with the experimental data, confirming the model's ability to simulate accurately nonlinear and dispersive effects for non-breaking waves. (10.1016/j.coastaleng.2016.04.003)
DOI : 10.1016/j.coastaleng.2016.04.003
Observations and modeling of San Diego beaches during El Niño
- Doria André
- Guza R.T.
- O 'Reilly William C
- Yates Marissa L.
Continental Shelf Research, Elsevier , 2016, 124, pp.153-164 . Subaerial sand levels were observed at five southern California beaches for 16 years, including notable El Niños in 1997–98 and 2009–10. An existing, empirical shoreline equilibrium model, driven with wave conditions estimated using a regional buoy network, simulates well the seasonal changes in subaerial beach width (e.g. the cross-shore location of the MSL contour) during non-El Niño years, similar to previous results with a 5-year time series lacking an El Niño winter. The existing model correctly identifies the 1997–98 El Niño winter conditions as more erosive than 2009–10, but overestimates shoreline erosion during both El Niños. The good skill of the existing equilibrium model in typical conditions does not necessarily extrapolate to extreme erosion on these beaches where a few meters thick sand layer often overlies more resistant layers. The modest over-prediction of the 2009–10 El Niño is reduced by gradually decreasing the model mobility of highly eroded shorelines (simulating cobbles, kelp wrack, shell hash, or other stabilizing layers). Over prediction during the more severe 1997–98 El Niño is corrected by stopping model erosion when resilient surfaces (identified with aerial imagery) are reached. The trained model provides a computationally simple (e.g. nonlinear first order differential equation) representation of the observed relationship between incident waves and shoreline change. (10.1016/j.csr.2016.05.008)
DOI : 10.1016/j.csr.2016.05.008
Accuracy and efficiency of two numerical methods of solving the potential flow problem for highly nonlinear and dispersive water waves
- Yates Marissa L.
- Benoit Michel
International Journal for Numerical Methods in Fluids, Wiley , 2015, 77, pp.616-640 . SUMMARY The accuracy and efficiency of two methods of resolving the exact potential flow problem for nonlinear waves are compared using three different 1DH test cases. The two model approaches use high-order finite difference schemes in the horizontal dimension and differ in the resolution of the vertical dimension. The first model uses high-order finite difference schemes also in the vertical, while the second model applies a spectral approach. The convergence, accuracy, and efficiency of the two models are demonstrated as a function of the temporal, horizontal, and vertical resolution for (1) the propagation of regular nonlinear waves in a periodic domain, (2) the motion of nonlinear standing waves in a domain with fully reflective boundaries, and (3) the propagation and shoaling of a train of waves on a slope. The spectral model approach converges more rapidly as a function of the vertical resolution. In addition, with equivalent vertical resolution, the spectral model approach shows enhanced accuracy and efficiency in the parameter range used for practical model applications. (10.1002/fld.3992)
DOI : 10.1002/fld.3992
Approaches to evaluate the recent impacts of sea-level rise on shoreline changes
- Le Cozannet Gonéri
- Garcin Manuel
- Yates Marissa L.
- Idier Déborah
- Meyssignac Benoit
Earth-Science Reviews, Elsevier , 2014, 138, pp.47-60 . While global sea level has risen by 20 cm since the mid-19th century, the role of this process in present-day and past shoreline mobility is still debated. In this paper, we review previous studies that explored the relations between sea-level rise and shoreline changes over the last few decades. Existing methods can be classified into two groups: (1) approaches based on the analysis of trends and variability in shoreline change observations, which investigate whether a correlation with the temporal or spatial patterns sea level changes can be established; and (2) approaches based on the comparison of shoreline observations with a coastal model outcome, which attempt to evaluate the contribution of sea-level rise to shoreline mobility using coastal evolution modeling tools. The existing applications of these methods face two common difficulties: first, shoreline data are often lacking or insufficiently resolved temporally to capture the dynamics of coastlines; and second, relative sea level along the coast is generally only known in a limited number of areas where tide gauges are available. These two challenges can be met, owing to the increasing amount of shoreline change observations and complementary geodetic techniques. The wide range of different interpretations regarding the role of sea-level rise in recent shoreline changes highlights the necessity to conduct specific studies that rely on local observations and models applicable in the local geomorphological context. (10.1016/j.earscirev.2014.08.005)
DOI : 10.1016/j.earscirev.2014.08.005
An AHP-derived method for mapping the physical vulnerability of coastal areas at regional scales
- Le Cozannet Gonéri
- Garcin Manuel
- Bulteau Thomas
- Mirgon Carola
- Yates Marissa L.
- Méndez Marta
- Baills Audrey
- Idier Déborah
- Oliveros Carlos
Natural Hazards and Earth System Sciences, Copernicus Publ. / European Geosciences Union , 2013, 13, pp.1209-1227 . Assessing coastal vulnerability to climate change at regional scales is now mandatory in France since the adoption of recent laws to support adaptation to climate change. However, there is presently no commonly recognised method to assess accurately how sea level rise will modify coastal processes in the coming decades. Therefore, many assessments of the physical component of coastal vulnerability are presently based on a combined use of data (e.g. digital elevation models, historical shoreline and coastal geomorphology datasets), simple models and expert opinion. In this study, we assess the applicability and usefulness of a multi-criteria decision-mapping method (the analytical hierarchy process, AHP) to map physical coastal vulnerability to erosion and flooding in a structured way. We apply the method in two regions of France: the coastal zones of Languedoc-Roussillon (north-western Mediterranean, France) and the island of La Réunion (south-western Indian Ocean), notably using the regional geological maps. As expected, the results show not only the greater vulnerability of sand spits, estuaries and low-lying areas near to coastal lagoons in both regions, but also that of a thin strip of erodible cliffs exposed to waves in La Réunion. Despite gaps in knowledge and data, the method is found to provide a flexible and transportable framework to represent and aggregate existing knowledge and to support long-term coastal zone planning through the integration of such studies into existing adaptation schemes. (10.5194/nhess-13-1209-2013)
DOI : 10.5194/nhess-13-1209-2013
Multidecadal Atoll Shoreline Change on Manihi and Manuae, French Polynesia
- Yates Marissa L.
- Le Cozannet Gonéri
- Garcin Manuel
- Salai Emilie
- Walker Patrice
Journal of Coastal Research, Coastal Education and Research Foundation , 2013, 29 (4), pp.870-882 . As interest in the impact of sea-level rise on atoll islands increases, this study contributes to the growing database of observations of shoreline changes on South Pacific Islands, where few observations are currently available. Historical aerial photographs and recent satellite images were used to evaluate multidecadal surface area and shoreline changes on two atolls in French Polynesia: Manihi and Manuae. During the 40- to 50-year study period, atoll island surface area primarily increased or remained stable on Manihi and decreased on Manuae. Distinct ocean and lagoon shoreline changes were observed in different geographical regions of each atoll. On Manihi, ocean shoreline accretion rates were larger on the NW rim than the SE rim. On Manuae, atoll islands on the NE rim were eroding on the lagoon side and accreting on the ocean side, whereas islands on the SE rim showed the opposite trend. Sea-level rise is often thought to cause atoll erosion, but in this study, lagoon and ocean shorelines both eroded and accreted over a period when sea-level rise rates were greater than the global mean. Surface area changes related directly to anthropogenic activities were identified on only two of the 47 atoll islands. After completing a classification of the incident wave field, it was hypothesized that waves have an important role in controlling the shoreline change variability. Additional field surveys and in situ observations are needed to validate this hypothesis and to understand better island response to changing forcing factors. (10.2112/JCOASTRES-D-12-00129.1)
DOI : 10.2112/JCOASTRES-D-12-00129.1