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Nicolas Bruneau

Imperial College London, Physics, Post-Doc

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- Tropical cyclones / typhoons and storm surges
- Wave- and tide-induced dynamics, wave-current interactions, turbulence, circulations and vortices
- Sediment transport, morphodynamics, coastal engineering and climate change
- Field experiments, data processing and analysis
- Global to regional modeling, numerical simulation, programming high performance computing
- Wave-dominated beaches and tidal inlets, lagoons, barrier islands, rip currents, southern polar ocean
Address: London

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University of Cambridge

Jayjit Majumdar

University of Kalyani

Armando Marques-Guedes

UNL - New University of Lisbon

Stefano R L Campana

University of Siena / Università di Siena

Queen Mary, University of London

Universiteit Utrecht

Cardiff University

Cardiff University

Blanca Figuerola

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

Fernando Ángel Fernández-Álvarez

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

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Papers by Nicolas Bruneau

Simulation of Morphodinamic Processes In Small Coastal Systems: Application to the Aljezur Coastal Stream (Portugal)

by Anabela Oliveira, Nicolas Bruneau, and André Fortunato

Page 1. Geophysical Research Abstracts Vol. 12, EGU2010-8753, 2010 EGU General Assembly 2010 © Au... more

Effect of Inlet Morphology and Wave Action on Pollutant Pathways and Sediment Dynamics in a Coastal Stream

by André Fortunato, Rui Taborda, and Nicolas Bruneau

The user has requested enhancement of the downloaded file.

Large-scale vorticity generation due to dissipating waves in the surf zone

Discrete and Continuous Dynamical Systems-series B, 2010

In this paper, we investigate the mechanisms which control the generation of wave-induced mean cu... more In this paper, we investigate the mechanisms which control the generation of wave-induced mean current vorticity in the surf zone. From the vertically-integrated and time-averaged momentum equations given recently by Smith [21], we obtain a vorticity forcing term related to differential broken-wave energy dissipation. Then, we derive a new equation for the mean current vorticity, from the nonlinear shallow water shock-wave theory. Both approaches are consistent, under the shallow water assumption, but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrization of the broken-wave energy dissipation.

MODELING OF COUPLED AND NONCOUPLED BEHAVIOR OF A DOUBLE SANDBAR SYSTEM: SELF-ORGANIZATION AND MORPHOLOGICAL FORCING

Coastal Engineering 2008 - Proceedings of the 31st International Conference, 2009

A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Aquitanian Coast, France

BRUNEAU, N.; BONNETON, P.; PEDREROS, R.; DUMAS, F. and IDIER, D., 2007. A New Morphodynamic Model... more BRUNEAU, N.; BONNETON, P.; PEDREROS, R.; DUMAS, F. and IDIER, D., 2007. A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Aquitanian Coast, France. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 932 - 936. Gold Coast, Australia, ISSN 0749.0208 Along coasts, waves and wave-induced currents are the main factors of morphological

Modélisation des évolutions de profil de plage

La Houille Blanche, 2010

Field observations of an evolving rip current on a meso-macrotidal well-developed inner bar and rip morphology

Continental Shelf Research, 2009

The Aquitanian Coast (France) is a high-energy meso-macrotidal environment exhibiting a highly va... more The Aquitanian Coast (France) is a high-energy meso-macrotidal environment exhibiting a highly variable double sandbar system. The inner and the outer bar generally exhibit a bar and rip morphology and persistent crescentic patterns, respectively. In June 2007, an intense five-day field experiment was carried out at Biscarrosse Beach. A large array of sensors was deployed on a well-developed southward-oriented bar and rip morphology. Daily topographic surveys were carried out together with video imaging to investigate beach morphodynamic evolution. During the experiment, offshore significant wave height ranged from 0.5 to 3 m, with a persistent shore-normal angle. This paper identifies two types of behavior of an observed rip current: (1) for low-energy waves, the rip current is active only between low and mid tide with maximum mean rip current velocity reaching 0.8 m/s for an offshore significant wave height (HsHs) lower than 1 m; (2) for high-energy waves (Hs≈Hs≈ 2.5–3 m), the rip current was active over the whole tide cycle with the presence of persistent intense offshore-directed flows between mid and high tide. For both low and high-energy waves, very low-frequency pulsations (15–30 min) of the mean currents are observed on both feeder and rip channels.A persistent slow shoreward migration of the sandbar was observed during the experiment while no significant alongshore migration of the system was measured. Onshore migration during the high-energy waves can be explained by different sediment transport processes such as flow velocity skewness, wave asymmetry or bed ventilation. High-frequency local measurements of the bed evolution show the presence of significant (in the order of 10 cm) fluctuations (in the order of 1 h). These fluctuations, observed for both low- and high-energy waves, are thought to be ripples and megaripples, respectively and may play an important but still poorly understood role in the larger scale morphodynamics. The present dataset improves the knowledge of rip dynamics as well as the morphological response of strongly alongshore non-uniform meso-macrotidal beaches.

Coupling mechanisms in double sandbar systems. Part 1: patterns and physical explanation

Earth Surface Processes and Landforms, 2010

Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understan... more Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understand localized beach and dune erosion during storms. In recent years, a paradigm shift from hydrodynamic template models to self-organization mechanisms occurred to explain the formation of these rhythmic features. In double sandbar systems, both the inner-and outerbar rip channels and crescentic planshapes are now believed to be free instabilities of the nearshore system arising through selforganization mechanisms alone. However, the occasional occurrence of one or two inner-bar rip channels within one outer-bar crescent suggests a forced, morphologically coupled origin. Here we use a nonlinear morphodynamic model to show that alongshore variability in outer-bar depth, and the relative importance of wave breaking versus wave focussing by refraction across the outer bar, is crucial to the inner-bar rip channel development. The coupling patterns simulated by our model are similar to those observed in the fi eld. Morphological coupling requires a template in the morphology (outer-bar geometry) which, through the positive feedback between fl ow, sediment transport and the evolving morphology (that is, self-organization) enforces the development of coupling patterns. We therefore introduce a novel mechanism that blurs the distinction between self-organization and template mechanisms. This mechanism may also be extended to explain the dynamics of other nearshore patterns, such as beach cusps. The impact of this novel mechanism on the alongshore variability of inner-bar rip channels is investigated in the companion paper.

Large-scale vorticity generation due to dissipating waves in the surf zone

Discrete and Continuous Dynamical Systems - Series B, 2010

In this paper, we investigate the mechanisms which control the generation of wave-induced mean cu... more In this paper, we investigate the mechanisms which control the generation of wave-induced mean current vorticity in the surf zone. From the vertically-integrated and time-averaged momentum equations given recently by Smith [21], we obtain a vorticity forcing term related to differential broken-wave energy dissipation. Then, we derive a new equation for the mean current vorticity, from the nonlinear shallow water shock-wave theory. Both approaches are consistent, under the shallow water assumption, but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrization of the broken-wave energy dissipation.

INFLUENCE OF THE WAVE REGIME IN COASTAL SEDIMENT BUDGET: PRESENT AND FUTURE SCENARIOS

Coastal Engineering Proceedings, 2012

Coupling mechanisms in double sandbar systems. Part 2: impact on alongshore variability of inner-bar rip channels

Earth Surface Processes and Landforms, 2010

Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understan... more Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understand localized beach and dune erosion during storms. In recent years, a paradigm shift from hydrodynamic template models to self-organization mechanisms occurred to explain the formation of these rhythmic features. In double sandbar systems, both the inner-and outerbar rip channels and crescentic planshapes are now believed to be free instabilities of the nearshore system arising through selforganization mechanisms alone. However, the occasional occurrence of one or two inner-bar rip channels within one outer-bar crescent suggests a forced, morphologically coupled origin. Here we use a nonlinear morphodynamic model to show that alongshore variability in outer-bar depth, and the relative importance of wave breaking versus wave focussing by refraction across the outer bar, is crucial to the inner-bar rip channel development. The coupling patterns simulated by our model are similar to those observed in the fi eld. Morphological coupling requires a template in the morphology (outer-bar geometry) which, through the positive feedback between fl ow, sediment transport and the evolving morphology (that is, self-organization) enforces the development of coupling patterns. We therefore introduce a novel mechanism that blurs the distinction between self-organization and template mechanisms. This mechanism may also be extended to explain the dynamics of other nearshore patterns, such as beach cusps. The impact of this novel mechanism on the alongshore variability of inner-bar rip channels is investigated in the companion paper.

Monitoring spatio-temporal variability of the Adour River turbid plume (Bay of Biscay, France) with MODIS 250-m imagery

Continental Shelf Research, 2014

ABSTRACT Increased loads of land-based pollutants through river plumes are a major threat to the ... more ABSTRACT Increased loads of land-based pollutants through river plumes are a major threat to the coastal water quality, ecosystems and sanitary heath. Identifying the coastal areas impacted by potentially polluted freshwaters is necessary to inform management policies and prevent degradation of the coastal environment. This study presents the first monitoring of the Adour River turbid plume (south-eastern Bay of Biscay, France) using multi-annual MODIS data Satellite data are processed using a regional algorithm that allows quantifying and mapping suspended matter in coastal waters. The results are used to investigate the spatial and temporal variability of the Adour River turbid plume and to identify the risk of exposure of coastal ecosystems to the turbid plume waters. Changes in river plume orientation and extent as well as suspended matter concentration rates discharged through the river are correlated to the main hydro-climatic forcings acting in the south-eastern Bay of Biscay. The Adour River turbid plume is shown to be a highly reactive system mainly controlled by the river discharge rates and modulated by the wind changes. Despite the relatively small size of the Adour River, the Adour River turbid plume can have a non-negligible impact on the water quality of the southern Bay of Biscay and the MSM and associated contaminant/nutrients transported within the Adour turbid river plume have the potential to be disseminated far away along the northern shoreline or offshore. The main areas of influence of the river plume are defined over multi-annual (3 years) and seasonal periods. The results presented in this study show the potential of 250-m MODIS images to monitor small river plumes systems and support management and assessment of the water quality in the south-eastern Bay of Biscay.

Future evolution of a tidal inlet due to changes in wave climate, Sea level and lagoon morphology (Óbidos lagoon, Portugal)

Continental Shelf Research, 2011

Tidal inlets are extremely dynamic, as a result of an often delicate balance between the effects ... more Tidal inlets are extremely dynamic, as a result of an often delicate balance between the effects of tides, waves and other forcings. Since the morphology of these inlets can affect navigation, water quality and ecosystem dynamics, there is a clear need to anticipate their evolution in order to promote adequate management decisions. Over decadal time scales, the position and size of tidal inlets are expected to evolve with the conditions that affect them, for instance as a result of climate change. A process-based morphodynamic modeling system is validated and used to analyze the effects of sea level rise, an expected shift in the wave direction and the reduction of the upper lagoon surface area by sedimentation on a small tidal inlet (Ó bidos lagoon, Portugal). A new approach to define yearly wave regimes is first developed, which includes a seasonal behavior, random inter-annual variability and the possibility to extrapolate trends. Once validated, this approach is used to produce yearly time series of wave spectra for the present and for the end of the 21st century, considering the local rotation trends computed using hindcast results for the past 57 years. Predictions of the mean sea level for 2100 are based on previous studies, while the bathymetry of the upper lagoon for the same year is obtained by extrapolation of past trends. Results show, and data confirm, that the Ó bidos lagoon inlet has three stable configurations, largely determined by the inter-annual variations in the wave characteristics. Both sea level rise and the reduction of the lagoon surface area will promote the accretion of the inlet. In contrast, the predicted rotation of the wave regime, within foreseeable limits, will have a negligible impact on the inlet morphology.

Modelled trends in Antarctic sea ice thickness

Journal of Climate, 2014

MODELING OF A HIGH-ENERGY RIP CURRENT DURING BISCARROSSE 2007 FIELD EXPERIMENT

Coastal Engineering 2008 - Proceedings of the 31st International Conference, 2009

Tide-induced flow signature in rip currents on a meso-macrotidal beach

Ocean Modelling, 2014

On rip-channelled beaches, intense rip currents are driven by waves due to alongshore variations ... more On rip-channelled beaches, intense rip currents are driven by waves due to alongshore variations in breaking-induced wave energy dissipation. This study addresses for the first time the potential development of tidal currents superimposed onto the wave-driven circulation. This phenomenon is observed on a rip-channelled meso-macrotidal beach (Biscarrosse, SW France). Field measurements show 20 to 45% stronger mean rip velocities during ebb than during flood. Numerical experiments reveal that this asymmetry is the signature of tidal currents developing over the rip channel morphology. This asymmetry is found to increase roughly linearly with increasing tidal range. These results are significant to beach safety and lifeguarding and stimulate further numerical exercises.

Interactions vagues-courants dans une embouchure tidale dominée par la houle

XIIèmes Journées, Cherbourg, 2012

Développement d'un nouveau modèle d'évolution de profil de plage

Ce papier présente le développement d'un modèle simple de profil de plage sableuses basé sur un c... more Ce papier présente le développement d'un modèle simple de profil de plage sableuses basé sur un couplage vagues/transport sédimentaire/évolution bathymétrique avec une approche à phase moyennée. Une nouvelle paramétrisation du transport sédimentaire résultant de l'asymétrie des vagues et de l'accélération près du fond est mise en place. Le modèle reproduit la migration de la barre vers la plage pendant les épisodes de temps calme et vers le large pendant les conditions énergétiques. La comparaison du modèle avec les expériences réalisées dans un canal à houle montre des résultats encourageants.

Importance of wave age and resonance in storm surges: The case Xynthia, Bay of Biscay

Ocean Modelling, 2012

This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude d... more This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude depression that severely hit the French central part of the Bay of Biscay on the 27-28th of February 2010. The main losses in human lives and damages were caused by the associated storm surge, which locally exceeded 1.5 m and peaked at the same time as a high spring tide, causing the flooding of low-lying coasts. A new storm surge modeling system was developed, based on the unstructured-grid circulation model SELFE and the spectral wave model WaveWatchIII. The modeling system was implemented over the North-East Atlantic Ocean and resulted in tidal and wave predictions with errors of the order of 3% and 15%, respectively. The storm surge associated with Xynthia was also well predicted along the Bay of Biscay, with only a slight underestimation of the surge peak by 3-8%. Numerical experiments were then performed to analyze the physical processes controlling the development of the storm surge and revealed firstly that the wind caused most of the water level anomaly through an Ekman setup process. The comparison between a wave-dependant and a quadratic parameterization to compute wind stress showed that the storm surge was strongly amplified by the presence of steep and young wind-waves, related to their rapid development in the restricted fetch of the Bay of Biscay. In the central part of the Bay of Biscay, both observed and predicted water level anomalies at landfall displayed $6 h oscillations, with amplitudes of up to 0.2 m (10-20% of the surge peak). An analytical shelf resonance model and numerical experiments demonstrated that the period of the observed oscillations corresponds to the resonant mode of the continental shelf in the central part of the Bay of Biscay. It is concluded that these oscillations originate from the interactions between the water level perturbation and the continental shelf and this phenomenon is expected to be relevant at other places along the world's coastlines.

Wave-current interactions in a wave-dominated tidal inlet

Journal of Geophysical Research: Oceans, 2013

ABSTRACT [1] Wave-current interactions play a major role in the dynamics of shallow tidal inlets.... more ABSTRACT [1] Wave-current interactions play a major role in the dynamics of shallow tidal inlets. This study investigates these interactions at a natural inlet, with a strong focus on current-induced changes on wave propagation. The analysis of hydrodynamic data collected at the Albufeira lagoon, Portugal, revealed spatiotemporal variations of water levels and wave heights along the inlet, attributed to wave-current interaction processes. We compared the simulations of a coupled wave-circulation modeling system, computed with and without waves, and propagated with and without current feedback. The wave-induced setup inside the lagoon represented 7%–15% of the offshore significant wave height. The accuracy of the wave&amp;#39;s predictions improved when current feedback was included. During ebb, the currents increased the wave height at the mouth of the inlet (up to 20%) and decreased the wave height in the inlet (up to 40%), due to current-induced refraction, steepness dissipation, and partial blocking. During flood, the currents decreased the wave height in the inlet (up to 10%) and increased the wave height at the exterior parts of the ebb shoal (up to 10%), due to current-induced refraction. These effects significantly attenuate seaward sediment fluxes during ebb and contribute to the sediment accretion in the inlet.

Simulation of Morphodinamic Processes In Small Coastal Systems: Application to the Aljezur Coastal Stream (Portugal)

by Anabela Oliveira, Nicolas Bruneau, and André Fortunato

Page 1. Geophysical Research Abstracts Vol. 12, EGU2010-8753, 2010 EGU General Assembly 2010 © Au... more

Effect of Inlet Morphology and Wave Action on Pollutant Pathways and Sediment Dynamics in a Coastal Stream

by André Fortunato, Rui Taborda, and Nicolas Bruneau

The user has requested enhancement of the downloaded file.

Large-scale vorticity generation due to dissipating waves in the surf zone

Discrete and Continuous Dynamical Systems-series B, 2010

In this paper, we investigate the mechanisms which control the generation of wave-induced mean cu... more In this paper, we investigate the mechanisms which control the generation of wave-induced mean current vorticity in the surf zone. From the vertically-integrated and time-averaged momentum equations given recently by Smith [21], we obtain a vorticity forcing term related to differential broken-wave energy dissipation. Then, we derive a new equation for the mean current vorticity, from the nonlinear shallow water shock-wave theory. Both approaches are consistent, under the shallow water assumption, but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrization of the broken-wave energy dissipation.

MODELING OF COUPLED AND NONCOUPLED BEHAVIOR OF A DOUBLE SANDBAR SYSTEM: SELF-ORGANIZATION AND MORPHOLOGICAL FORCING

Coastal Engineering 2008 - Proceedings of the 31st International Conference, 2009

A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Aquitanian Coast, France

BRUNEAU, N.; BONNETON, P.; PEDREROS, R.; DUMAS, F. and IDIER, D., 2007. A New Morphodynamic Model... more BRUNEAU, N.; BONNETON, P.; PEDREROS, R.; DUMAS, F. and IDIER, D., 2007. A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Aquitanian Coast, France. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 932 - 936. Gold Coast, Australia, ISSN 0749.0208 Along coasts, waves and wave-induced currents are the main factors of morphological

Modélisation des évolutions de profil de plage

La Houille Blanche, 2010

Field observations of an evolving rip current on a meso-macrotidal well-developed inner bar and rip morphology

Continental Shelf Research, 2009

The Aquitanian Coast (France) is a high-energy meso-macrotidal environment exhibiting a highly va... more The Aquitanian Coast (France) is a high-energy meso-macrotidal environment exhibiting a highly variable double sandbar system. The inner and the outer bar generally exhibit a bar and rip morphology and persistent crescentic patterns, respectively. In June 2007, an intense five-day field experiment was carried out at Biscarrosse Beach. A large array of sensors was deployed on a well-developed southward-oriented bar and rip morphology. Daily topographic surveys were carried out together with video imaging to investigate beach morphodynamic evolution. During the experiment, offshore significant wave height ranged from 0.5 to 3 m, with a persistent shore-normal angle. This paper identifies two types of behavior of an observed rip current: (1) for low-energy waves, the rip current is active only between low and mid tide with maximum mean rip current velocity reaching 0.8 m/s for an offshore significant wave height (HsHs) lower than 1 m; (2) for high-energy waves (Hs≈Hs≈ 2.5–3 m), the rip current was active over the whole tide cycle with the presence of persistent intense offshore-directed flows between mid and high tide. For both low and high-energy waves, very low-frequency pulsations (15–30 min) of the mean currents are observed on both feeder and rip channels.A persistent slow shoreward migration of the sandbar was observed during the experiment while no significant alongshore migration of the system was measured. Onshore migration during the high-energy waves can be explained by different sediment transport processes such as flow velocity skewness, wave asymmetry or bed ventilation. High-frequency local measurements of the bed evolution show the presence of significant (in the order of 10 cm) fluctuations (in the order of 1 h). These fluctuations, observed for both low- and high-energy waves, are thought to be ripples and megaripples, respectively and may play an important but still poorly understood role in the larger scale morphodynamics. The present dataset improves the knowledge of rip dynamics as well as the morphological response of strongly alongshore non-uniform meso-macrotidal beaches.

Coupling mechanisms in double sandbar systems. Part 1: patterns and physical explanation

Earth Surface Processes and Landforms, 2010

Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understan... more Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understand localized beach and dune erosion during storms. In recent years, a paradigm shift from hydrodynamic template models to self-organization mechanisms occurred to explain the formation of these rhythmic features. In double sandbar systems, both the inner-and outerbar rip channels and crescentic planshapes are now believed to be free instabilities of the nearshore system arising through selforganization mechanisms alone. However, the occasional occurrence of one or two inner-bar rip channels within one outer-bar crescent suggests a forced, morphologically coupled origin. Here we use a nonlinear morphodynamic model to show that alongshore variability in outer-bar depth, and the relative importance of wave breaking versus wave focussing by refraction across the outer bar, is crucial to the inner-bar rip channel development. The coupling patterns simulated by our model are similar to those observed in the fi eld. Morphological coupling requires a template in the morphology (outer-bar geometry) which, through the positive feedback between fl ow, sediment transport and the evolving morphology (that is, self-organization) enforces the development of coupling patterns. We therefore introduce a novel mechanism that blurs the distinction between self-organization and template mechanisms. This mechanism may also be extended to explain the dynamics of other nearshore patterns, such as beach cusps. The impact of this novel mechanism on the alongshore variability of inner-bar rip channels is investigated in the companion paper.

Large-scale vorticity generation due to dissipating waves in the surf zone

Discrete and Continuous Dynamical Systems - Series B, 2010

In this paper, we investigate the mechanisms which control the generation of wave-induced mean cu... more In this paper, we investigate the mechanisms which control the generation of wave-induced mean current vorticity in the surf zone. From the vertically-integrated and time-averaged momentum equations given recently by Smith [21], we obtain a vorticity forcing term related to differential broken-wave energy dissipation. Then, we derive a new equation for the mean current vorticity, from the nonlinear shallow water shock-wave theory. Both approaches are consistent, under the shallow water assumption, but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrization of the broken-wave energy dissipation.

INFLUENCE OF THE WAVE REGIME IN COASTAL SEDIMENT BUDGET: PRESENT AND FUTURE SCENARIOS

Coastal Engineering Proceedings, 2012

Coupling mechanisms in double sandbar systems. Part 2: impact on alongshore variability of inner-bar rip channels

Earth Surface Processes and Landforms, 2010

Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understan... more Crescentic sandbars and rip channels along wave-dominated sandy beaches are relevant to understand localized beach and dune erosion during storms. In recent years, a paradigm shift from hydrodynamic template models to self-organization mechanisms occurred to explain the formation of these rhythmic features. In double sandbar systems, both the inner-and outerbar rip channels and crescentic planshapes are now believed to be free instabilities of the nearshore system arising through selforganization mechanisms alone. However, the occasional occurrence of one or two inner-bar rip channels within one outer-bar crescent suggests a forced, morphologically coupled origin. Here we use a nonlinear morphodynamic model to show that alongshore variability in outer-bar depth, and the relative importance of wave breaking versus wave focussing by refraction across the outer bar, is crucial to the inner-bar rip channel development. The coupling patterns simulated by our model are similar to those observed in the fi eld. Morphological coupling requires a template in the morphology (outer-bar geometry) which, through the positive feedback between fl ow, sediment transport and the evolving morphology (that is, self-organization) enforces the development of coupling patterns. We therefore introduce a novel mechanism that blurs the distinction between self-organization and template mechanisms. This mechanism may also be extended to explain the dynamics of other nearshore patterns, such as beach cusps. The impact of this novel mechanism on the alongshore variability of inner-bar rip channels is investigated in the companion paper.

Monitoring spatio-temporal variability of the Adour River turbid plume (Bay of Biscay, France) with MODIS 250-m imagery

Continental Shelf Research, 2014

ABSTRACT Increased loads of land-based pollutants through river plumes are a major threat to the ... more ABSTRACT Increased loads of land-based pollutants through river plumes are a major threat to the coastal water quality, ecosystems and sanitary heath. Identifying the coastal areas impacted by potentially polluted freshwaters is necessary to inform management policies and prevent degradation of the coastal environment. This study presents the first monitoring of the Adour River turbid plume (south-eastern Bay of Biscay, France) using multi-annual MODIS data Satellite data are processed using a regional algorithm that allows quantifying and mapping suspended matter in coastal waters. The results are used to investigate the spatial and temporal variability of the Adour River turbid plume and to identify the risk of exposure of coastal ecosystems to the turbid plume waters. Changes in river plume orientation and extent as well as suspended matter concentration rates discharged through the river are correlated to the main hydro-climatic forcings acting in the south-eastern Bay of Biscay. The Adour River turbid plume is shown to be a highly reactive system mainly controlled by the river discharge rates and modulated by the wind changes. Despite the relatively small size of the Adour River, the Adour River turbid plume can have a non-negligible impact on the water quality of the southern Bay of Biscay and the MSM and associated contaminant/nutrients transported within the Adour turbid river plume have the potential to be disseminated far away along the northern shoreline or offshore. The main areas of influence of the river plume are defined over multi-annual (3 years) and seasonal periods. The results presented in this study show the potential of 250-m MODIS images to monitor small river plumes systems and support management and assessment of the water quality in the south-eastern Bay of Biscay.

Future evolution of a tidal inlet due to changes in wave climate, Sea level and lagoon morphology (Óbidos lagoon, Portugal)

Continental Shelf Research, 2011

Tidal inlets are extremely dynamic, as a result of an often delicate balance between the effects ... more Tidal inlets are extremely dynamic, as a result of an often delicate balance between the effects of tides, waves and other forcings. Since the morphology of these inlets can affect navigation, water quality and ecosystem dynamics, there is a clear need to anticipate their evolution in order to promote adequate management decisions. Over decadal time scales, the position and size of tidal inlets are expected to evolve with the conditions that affect them, for instance as a result of climate change. A process-based morphodynamic modeling system is validated and used to analyze the effects of sea level rise, an expected shift in the wave direction and the reduction of the upper lagoon surface area by sedimentation on a small tidal inlet (Ó bidos lagoon, Portugal). A new approach to define yearly wave regimes is first developed, which includes a seasonal behavior, random inter-annual variability and the possibility to extrapolate trends. Once validated, this approach is used to produce yearly time series of wave spectra for the present and for the end of the 21st century, considering the local rotation trends computed using hindcast results for the past 57 years. Predictions of the mean sea level for 2100 are based on previous studies, while the bathymetry of the upper lagoon for the same year is obtained by extrapolation of past trends. Results show, and data confirm, that the Ó bidos lagoon inlet has three stable configurations, largely determined by the inter-annual variations in the wave characteristics. Both sea level rise and the reduction of the lagoon surface area will promote the accretion of the inlet. In contrast, the predicted rotation of the wave regime, within foreseeable limits, will have a negligible impact on the inlet morphology.

Modelled trends in Antarctic sea ice thickness

Journal of Climate, 2014

MODELING OF A HIGH-ENERGY RIP CURRENT DURING BISCARROSSE 2007 FIELD EXPERIMENT

Coastal Engineering 2008 - Proceedings of the 31st International Conference, 2009

Tide-induced flow signature in rip currents on a meso-macrotidal beach

Ocean Modelling, 2014

On rip-channelled beaches, intense rip currents are driven by waves due to alongshore variations ... more On rip-channelled beaches, intense rip currents are driven by waves due to alongshore variations in breaking-induced wave energy dissipation. This study addresses for the first time the potential development of tidal currents superimposed onto the wave-driven circulation. This phenomenon is observed on a rip-channelled meso-macrotidal beach (Biscarrosse, SW France). Field measurements show 20 to 45% stronger mean rip velocities during ebb than during flood. Numerical experiments reveal that this asymmetry is the signature of tidal currents developing over the rip channel morphology. This asymmetry is found to increase roughly linearly with increasing tidal range. These results are significant to beach safety and lifeguarding and stimulate further numerical exercises.

Interactions vagues-courants dans une embouchure tidale dominée par la houle

XIIèmes Journées, Cherbourg, 2012

Développement d'un nouveau modèle d'évolution de profil de plage

Ce papier présente le développement d'un modèle simple de profil de plage sableuses basé sur un c... more Ce papier présente le développement d'un modèle simple de profil de plage sableuses basé sur un couplage vagues/transport sédimentaire/évolution bathymétrique avec une approche à phase moyennée. Une nouvelle paramétrisation du transport sédimentaire résultant de l'asymétrie des vagues et de l'accélération près du fond est mise en place. Le modèle reproduit la migration de la barre vers la plage pendant les épisodes de temps calme et vers le large pendant les conditions énergétiques. La comparaison du modèle avec les expériences réalisées dans un canal à houle montre des résultats encourageants.

Importance of wave age and resonance in storm surges: The case Xynthia, Bay of Biscay

Ocean Modelling, 2012

This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude d... more This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude depression that severely hit the French central part of the Bay of Biscay on the 27-28th of February 2010. The main losses in human lives and damages were caused by the associated storm surge, which locally exceeded 1.5 m and peaked at the same time as a high spring tide, causing the flooding of low-lying coasts. A new storm surge modeling system was developed, based on the unstructured-grid circulation model SELFE and the spectral wave model WaveWatchIII. The modeling system was implemented over the North-East Atlantic Ocean and resulted in tidal and wave predictions with errors of the order of 3% and 15%, respectively. The storm surge associated with Xynthia was also well predicted along the Bay of Biscay, with only a slight underestimation of the surge peak by 3-8%. Numerical experiments were then performed to analyze the physical processes controlling the development of the storm surge and revealed firstly that the wind caused most of the water level anomaly through an Ekman setup process. The comparison between a wave-dependant and a quadratic parameterization to compute wind stress showed that the storm surge was strongly amplified by the presence of steep and young wind-waves, related to their rapid development in the restricted fetch of the Bay of Biscay. In the central part of the Bay of Biscay, both observed and predicted water level anomalies at landfall displayed $6 h oscillations, with amplitudes of up to 0.2 m (10-20% of the surge peak). An analytical shelf resonance model and numerical experiments demonstrated that the period of the observed oscillations corresponds to the resonant mode of the continental shelf in the central part of the Bay of Biscay. It is concluded that these oscillations originate from the interactions between the water level perturbation and the continental shelf and this phenomenon is expected to be relevant at other places along the world's coastlines.

Wave-current interactions in a wave-dominated tidal inlet

Journal of Geophysical Research: Oceans, 2013

ABSTRACT [1] Wave-current interactions play a major role in the dynamics of shallow tidal inlets.... more ABSTRACT [1] Wave-current interactions play a major role in the dynamics of shallow tidal inlets. This study investigates these interactions at a natural inlet, with a strong focus on current-induced changes on wave propagation. The analysis of hydrodynamic data collected at the Albufeira lagoon, Portugal, revealed spatiotemporal variations of water levels and wave heights along the inlet, attributed to wave-current interaction processes. We compared the simulations of a coupled wave-circulation modeling system, computed with and without waves, and propagated with and without current feedback. The wave-induced setup inside the lagoon represented 7%–15% of the offshore significant wave height. The accuracy of the wave&amp;#39;s predictions improved when current feedback was included. During ebb, the currents increased the wave height at the mouth of the inlet (up to 20%) and decreased the wave height in the inlet (up to 40%), due to current-induced refraction, steepness dissipation, and partial blocking. During flood, the currents decreased the wave height in the inlet (up to 10%) and increased the wave height at the exterior parts of the ebb shoal (up to 10%), due to current-induced refraction. These effects significantly attenuate seaward sediment fluxes during ebb and contribute to the sediment accretion in the inlet.