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Coastal and Continental Morphodynamics laboratory

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The "Coastal and Continental Morphodynamics" laboratory (M2C) is a Joint Research Unit (UMR 6143) created in 1996, under the supervision of the French National Center for Scientific Research (CNRS), the university of Caen Normandie (UNICAEN) and the university of Rouen Normandy (URN). The staff of the laboratory includes 86 persons: 37 researchers, 21 engineers and technicians, 28 PhD students. The research of the M2C laboratory focuses on the characterization and modeling of natural processes dynamics in different compartments along the LAND-SEA continuum, at different scales of time and space. The research is organized into 5 themes:
  • Watershed
  • Estuary
  • Coastal


This research is carried out with an interdisciplinary approach integrating researchers specialized in mechanics, geosciences, oceanography, hydrology, microbiology and ecology of organisms. Our research combines in-situ measurements with numerous dedicated equipment, experimental approaches and numerical moodeling.

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Last publications

The Central English Channel troughs correspond to elongated incisions up to 250 m-deep, at several locations at the bottom of this sea corridor. Depending on their location, they are usually interpreted as part of the submerged quaternary paleovalley network or as resulting from megaflood events. Shedding light on these features, their age, and the processes underlying their development is key for understanding their significance in terms of event geology. The interpretation of a dense grid of high-resolution marine seismic data acquired in the Bay of Seine area reveals that the extensive Quaternary paleovalley and trough network commonly as associated to the "Channel River" system is actually subdivided into at least two superimposed and unrelated incised networks. The overlying network corresponds to fluvial incisions developing during low sea-level conditions of Pleistocene time and connects to the present day fluvial network. The underlying network corresponds to the troughs and appears as a complex, deeper, relatively discontinuous and isolated network. This older network shows unexpected local incision depth up to c.350-400 m-deep and complex sedimentary infill involving several sedimentary processes and environments from fluvial to tidal and shallow-marine. We discuss these observations and their implications for understanding the origin, age and development of the troughs all over the English Channel, from the Dangeard Troughs in the Dover Strait to the Hurd Deep at the western end. We also raise questions about the significance of these large incised features in terms of source-to-sink system of northwestern Europe.

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A prediction model for the turbulent kinetic energy (TKE) induced by tidal-currents is proposed as a function of the barotropic velocity only, along with a robust method evaluating the different parameters involved using Acoustic Doppler Current Profiler (ADCP) measurements from Alderney Race. We find that the model is able to reproduce correctly the TKE profiles with coefficients of correlation on average higher than 0.90 and normalised root-mean-square errors (NRMSE) less than 14%. Different profiles are also tested for the mean velocity, no satisfactory prediction model is found but we are able to have decent estimates of the velocity shear and friction velocity. Two applications are then carried out. First the turbulent budget terms are estimated and discussed. We identify the turbulent production and dissipation of TKE as the most important mechanisms, then we discuss the validity of several theoretical results derived for isotropic turbulence for this application. A strong departure for the estimation of the turbulent dissipation is notably found and explained by the turbulent anisotropy. At last the prediction model for the TKE is used to infer the wave-induced TKE. We show the importance of removing the tidal component, waves can have a strong influence down to mid-depth.

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Surface-wave methods have a wide range of possible applications in the monitoring of near-surface media. In classical monitoring methods, data measured at different times are inverted separately and independently, and the difference in the inversion results reflects the temporal changes in the medium. However, the results obtained in this way can be affected by the reproducibility of experimental measurements, measurement and inversion uncertainties, etc. In this study, we introduce Differential Inversion in surface-wave methods, which uses the difference between measured data as inversion input data, instead of the measured data themselves. More precisely, a linear approximation of Rayleigh wave phase velocity associated with its sensitivity kernel is used to relate the data difference with the model variations. This differential inversion approach is firstly tested with numerical data generated in a series of two-layer models in order to estimate the limitations of the linear approximation with a global inversion approach. It is shown that when the shear-wave velocity variation is more than 5%, the linear assumption is no longer relevant. With respect to the 5% of variation, we apply the differential inversion approach on laboratory data, obtained from three reduced-scale epoxy-resin two-layer models. The results show the feasibility of the differential inversion to estimate the shear-wave velocity differences between epoxy-resin models. The short calculation time is one of its advantages. However, a good estimation on the baseline is required in order to calculate the sensitivity kernel. Finally, the robustness of the proposed approach is verified by numerical data, using the Spectral Element Method to simulate wave propagation in the presence of an under-surface cavity. Keywords: Surface-wave methods, Differential inversion, Small scale models, Rayleigh wave sensitivity kernel, Spectral Element Method.

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Coastal ecosystems provide a wide range of valuable ecosystem services (ES) for human wellbeing. Such services depend on the functioning and structure of ecosystems. Unfortunately, these ecosystems are threatened by humans, directly impairing their ability to provide these services. In order to predict such changes, we used a food web model to forecast potential spatial changes in ES supply in the Seine Bay (English Channel), due to climate change effects (CC) and the setup of an offshore wind farm (OWF). Three ES were studied, food production from fishing, top predator production for cultural purposes and the potential resistance of the ecosystem inferred from its organization. The ability of the Seine Bay ecosystem to produce food appears to be negatively impacted by the effect of climate change. Because of the important economic role of fishing in Normandy, such changes could percolate on the entire social and economic system of the bay. The Courseulles-sur-Mer offshore wind farm appears to increase the supply of services and limit the impact of climate change at the local spatial scale, which could give stakeholders insights into mitigating the effects of climate change. Such ecosystem approach enables for a more integrative view of ES supply, through the characterization of the entire system functioning.

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Turbulence in the water flow causes small-scale variations in the mechanical stress acting on submerged tidal turbines. As such it increases their fatigue loading and impacts greatly their lifetime. It is therefore essential for engineers to have an accurate knowledge and characterisation of turbulence at a given site as they design the structures to be deployed. The strength of the tidal currents is the main parameter influencing the intensity of turbulence through their friction with the sea bed. However, most potential tidal energy sites are located in a coastal environment with shallow enough water depths so that the direct impact of waves on turbulence can not be overlooked. Steepness-induced wave breaking is indeed observed to increase the turbulent mixing for such applications. In this context, we propose to estimate the contribution of surface processes to the total turbulence in Alderney Race, France, the most energetic tidal site in western Europe. The turbulent kinetic energy (TKE) specifically induced by waves and wind is characterised using measurements from a 5-beams ADCP deployed between 27/02/2018 and 06/07/2018.Analytical profiles are fitted to the data, the only fitting parameter of the model is an evaluation of the turbulence penetration depth, it determines how deep surface processes impact the water column. Its dependence towards mean wave and current parameters is studied. The results do not allow to conclude on the nature of turbulence observed in the mid water column.

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Abstract The southeastern tip of Cuba Island is limited to the south by the N‐Caribbean boundary. By revisiting the impressive sequences of coastal terraces of this region, we decipher the Quaternary deformation pattern of this plate boundary. We present a detailed mapping of coastal terraces uplifted over a hundred kilometers of coastline, and U/Th dating. At Punta de Maisí, the deformation pattern shows (a) a faster uplift close to the transform boundary and (b) a northward propagation of folding produced by the convergence of the Bahamas platform toward the Caribbean plate. Along the southern coast of Punta de Maisí, the sequence displays 29 coastal terraces up to 520 m in elevation and a upper Pleistocene uplift rate of 0.23 ± 0.07 mm yr −1 . We interpret this deformation as resulting from an offshore north‐dipping reverse fault near the coast. This uplift rate corresponds to 3% to 1.6% of the short‐term horizontal slip rate of Septentrional Oriente Fault Zone (10 ± 0.1 mm yr −1 ). Along the northern coast of Punta de Maisí, the sequence displays height coastal terraces up to 220 m in elevation and the uplift rates amount to 0.1 ± 0.05 mm yr −1 and likely result from the reverse faulting and folding associated with the offshore North Hispaniola Fault Zone. Uplift rates quickly decrease to the West, in agreement with the westward decrease in the activity of the North Hispaniola Fault Zone due to the docking of the Bahamas Platform against Cuba, while the platform more gently underthrusts Cuba to the East.

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La couverture sédimentaire de la Manche est le résultat de l’héritage complexe des cycles climato-eustatiques plio-quaternaires, dont la dernière transgression post-glaciaire, d’un contexte hydrodynamique dominé par un forçage tidal intense, et d’une forte production carbonatée. On observe ainsi sur une couverture silicoclastique peu épaisse, à l’exception du remplissage des paléo-vallées du fleuve Manche et du prisme sédimentaire picard, des sédiments bioclastiques issus d’assemblages de type « Foramol » dont la teneur en carbonate peut atteindre plus de 70 %. Les sédiments mixtes, résultat d’une production carbonatée au sein d’un substrat sédimentaire silicoclastique, sont mobilisés par les processus hydrodynamiques prévalant dans le milieu littoral. Les sédiments transportés dans le domaine subtidal et intertidal par les courants de marée se structurent en dunes ou en bancs, et les sédiments se trouvant dans la zone d’action des houles participent à la construction des barrières littorales. Les différences de propriétés physiques entre les particules bioclastiques et silicoclastiques induisent des différences de comportement hydrodynamique. Elles engendrent une ségrégation qui produit de l’hétérogénéité au sein des corps sédimentaires, et des morphologies de dépôts carbonatés qui diffèrent de leurs équivalents silicoclastiques. Comprendre et caractériser le fonctionnement des environnements sédimentaires mixtes silico-bioclastiques, comme la Manche, est essentiel pour mieux interpréter les enregistrements fossiles et la nature des réservoirs géologiques, mais également pour mieux modéliser et prédire la dynamique des environnements côtiers actuels. Dans cet exposé, nous présenterons les travaux expérimentaux menés ces dernières années au laboratoire de Morphodynamique Continentale et Côtière (CNRS / Univ. Caen) sur cette thématique. Nous évoquerons la variabilité interspécifique des seuils de mise en mouvement et des vitesses de sédimentation de débris de mollusques, ainsi que les processus de ségrégation qui structurent les dunes tidales ou les barrières littorales constituées de sédiments mixtes silico-bioclastiques. Nous conclurons sur les perspectives de recherche qui s’ouvrent sur les sédiments carbonatés de la Manche, et en particulier sur l’importance de quantifier cette production carbonatée dans un contexte de changement global et d’élévation du niveau marin.

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Recent sampling of the upper part of the Seine estuary (oligohaline, freshwater reaches) has led to the observation of the non-indigenous amphipod Chelicorophium curvispinum for the first time in the downstream part of the Seine Basin (between the Tancarville Bridge and Paris). Specimens were collected using a suprabenthic sledge along a salinity gradient ranging from freshwater to mesohaline, with observations of C. curvispinum all along this gradient. Samples collected were characterized by a relatively small number of individuals, reaching a maximum abundance of 15 individuals / 100 m 3 when temperatures were the highest, during the summer. The sex ratio was dominated by females, with approximately twice as many females than males. Interestingly, adults reach a size which allowed the reproduction of the species, but no ovigerous females were observed. Despite the rapid expansion of C. curvispinum in the Seine estuary, this study cannot assess whether this species should be considered as invasive in the Seine Basin. Nevertheless, as the sampling was carried out within the navigation channel, further observations will be necessary to determine the abundance of this species on soft and hard bottoms of the riverbanks.

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International collaboration (co-authors)



M2C lab. in Caen

Morphodynamique Continentale et Côtière
Université de Caen Normandie (Campus 1)
24 rue des Tilleuls
14000 Caen Cedex

M2C lab. in Rouen

Morphodynamique Continentale et Côtière
Université de Rouen Normandie (bâtiment Blondel Nord)
Place Emile Blondel
76821 Mont-Saint-Aignan Cedex