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The aim of this study is to analyse and to quantify the fine particles transfer (i.e.< 63 μm) in the marine part of the man-altered macrotidal Seine estuary (France) by (i) an analysis of a two year time-series of altimeter data, which reveals the bed elevation variations on an intertidal mudflatd located at the Seine mouth and (ii) measurements of the concentration of suspended particulate matter (SPM) contained within the turbidity maximum (TM). The results of this analysis reveal that sedimentation on the mudflat is mainly controlled by the dynamics of the TM such that during the largest spring tides (i.e. tidal ranges > 7.1 m). Then, deposition of SPM from the turbidity maximum becomes important, allowing fine particles to settle on the mudflat, where the current velocities are low (< 0.4 m s− 1). On tides of lower range (< 7.1 m) bed elevation levels suggest that erosion of the mudflat surface dominates, however dewatering processes also occur in the soft mud deposits resulting in compaction. During periods of wave activity and periods of increasing river discharge, the mudflat surface experiences rapid erosion. These periods of erosion (sudden or progressive) imply a transfer of fine-grained material from the mudflat surface back into the TM.The long term (∼ 22 months), high frequency (1 measurement every 10 min) and high resolution (0.6 mm) dataset obtained from the altimeter allows quantification of the volume of material exchanged between the intertidal area and the estuarine standing stock of SPM. The maximum of deposition on the studied mudflat during the study was of 27 cm, with highest deposition occurring after the periods of highest river flow and implying that between 25 and 40% of the maximum estimated mass of SPM held within the estuarine TM (300,000–500,000 T) had been temporarily deposited on the mudflat. Likewise following periods of resuspension by wave activity, bed elevations reduced by an order of ∼ 1 cm, suggesting a release of between 1–1.5% of the TM load from the mudflat back into suspension.The study shows that lateral exchanges of sediment between the intertidal reaches of the estuary and the water column are an important part of the sediment budget, and that the supply of sediment available for deposition (i.e. the TM) has a causal relationship with sedimentation rates experienced by intertidal mudflats.

International audience

Physical modelling has been developed in order to simulate the effects of periglacial erosion processes on the degradation of slopes and scarps. Data from 41 experimental freeze–thaw cycles are presented. They attest to the efficiency of periglacial processes that control both erosion and changes in scarp morphology: (i) cryoexpulsion leads to an increase of scarp surface roughness and modifies significantly the internal structure of the active layer; (ii) combined effects of frost creep and gelifluction lead to slow and gradual downslope displacements of the active layer (0·3 cm/cycle); (iii) debris flows are associated with the most significant changes in scarp morphology and are responsible for the highest rate of scarp erosion; (iv) quantification of the erosion rate gives values close to 1 cm3 cm−2 for 41 freeze–thaw cycles. These experimental results are consistent with field data acquired along the La Hague fault scarp (Normandy, France) where an erosion rate of 4·6 ± 1 m3 m−2 per glacial stage has been computed from the volume of natural slope deposits stored during the Weichselian glacial stage. These results show that moist periglacial erosion processes could lead to an underestimation of Plio-Quaternary deformation in the mid-latitudes. Copyright © 2006 John Wiley & Sons, Ltd.

19 pages; The conclusions from the research project in the Laigne valley show the relevance of the geoarchaeological approach conducted on two scales of investigation. The first, over the entire alluvial plain, allows general data to be collected which characterise the specific functions of each catchment basin during the Holocene period : determination of sedimentary sequences, evolution of vegetation and phases of human occupation. The second is a geoarchaeological approach on the scale of a test site : it demonstrates and dates as precisely as possible interactions between natural events and human activities which reveal changes to the entire catchment basin.; Les conclusions issues de l'expérience menée dans la vallée de la Laigne mettent en évidence la pertinence de la démarche géoarchéologique menée à deux échelles d'investigation. La première, conduite sur l'ensemble de la plaine alluviale, permet de recueillir les données générales qui caractérisent le fonctionnement spécifique de ce bassin versant pendant la période holocène : détermination des séquences sédimentaires, végétales et des phases d'occupation. La seconde est celle d'une démarche géoarchéologique menée à l'échelle d'un site-test : elle met en évidence et date le plus précisément possible des interactions entre événements naturels et activités humaines, interactions révélatrices des mutations de l'ensemble du bassin versant. Le contrôle anthropique de la sédimentation alluviale au cours du 1er s., c'est-à-dire lors de la phase de romanisation de ce terroir, est ainsi clairement mis en évidence.

Burgundian vineyards are affected by erosion phenomena that induce sediment transfer along hillslopes. The vineyard under study has occupied the western Bressan rift border for 1000 years, benefiting from marly limestone bedrock and its silt-sand covering. The combined effects of rainstorms and monoculture on slopes reaching 25°, induce a high level of erosion in the arable soil layer. Quantification of erosion rates on a pluri-decennial scale, using vine roots'as a palaeo-surface marker, has been performed on three parcels on three sites along the Côtes-de-Nuits and Côtes-de-Beaune. Assessed erosion rates of around 1 mm.yr-1 characterise current erosive dynamics involving a critical situation for soil sustainability, and consequently for terroir conservation., I vigneti della costa della Borgogna presentano fenomeni di erosione lungo i versanti. Questi vigneti occupano il bordo degli altopiani che sono sospesi sulla pianura della Bresse, caratterizzate da substrati marno-calcarei giurassici e da coperture superficiali limoso-sabbiose. L’effetto combinato di una monocultura su forti pendenze e di forti temporali provoca l’erosione di strati arabili dove sono state piantate le viti. Una quantificazione dell’erosione è stata realizzata su tre zone della Côte de Nuits e della Côte de Beaune. I tassi d’erosione che raggiungono 1 mm.an-1 indicano che la dinamica attuale di tali altopiani è in una situazione critica per la conservazione del suolo e dunque del territorio.

From the late 1970s, many scientific publications have made more comprehensible the production and transportation mechanisms of woody debris in the rivers. Most of these studies were geographically held on creeks in North America, in regions characterized by wood industry and old temperate forests. The knowledge about the woody debris process in greater rivers is still deficient. The goal is now to identify, on the hydrographic network scale, the origin and the transportation factors of woody debris, in order to point the mechanisms and the areas of production and stocking. The results of this study should lead in a near future to suitable solutions for the maintenance of the hydrographic system and prevention of the associated risks. The Isère River upstream of Grenoble is concerned by all these questions. Thus, a global study was engaged for this thesis on this specific hydrographic network. It considers three thematic axis. A first step was to cover the Isère River between the dam of Aigueblanche and Grenoble, the Arc River from Saint-Jean-de-Maurienne to the confluence with the Isère River, the Arly River from Ugine to the Isère River. The result allowed to map the different forms of woody debris accumulation along the riverbed, and to identify the preferential stocking zones (and vice-versa) as well as certain parameters controlling the woody debris spatial distribution along the riverbed. The second step considered the highly woody crowded zones. Measurements were taken of the trunks piled in the different riverbeds to elaborate the identity card of the woody debris. Three methodological tests were then done to identify the geographic origin of the woody debris stocked in the Isère riverbed below Albertville. The third step presents the results of a test started in 2002 that consisted in tracing debris and of the experimentation held in June 2003 while operating a dam release. Then we studied the woody debris dynamic according to the hydrology of the rivers. From the results obtained, management propositions were made. There objectives are to diminish the flooding and damaging risks of buildings and built areas, to diminish the costs of debris removal and exploitation constraints of dams and bridges. Another aim was to find a solution to avoid systematic maintenance on the full-length bed, which is financially and ecologically expensive, and to offer some rules promoting the impact of the maintenance policy applied., Depuis la fin des années 1970, de nombreuses publications scientifiques ont permis de mieux comprendre les mécanismes de production et de transport des bois morts dans les cours d'eau. La plupart de ces travaux se sont concentrés géographiquement sur des torrents ou des petits cours d'eau localisés en Amérique du Nord, dans des régions caractérisées par l'industrie forestière et la présence de vieilles forêts tempérées. Les connaissances relatives à la dynamique du bois mort dans les cours d'eau de grande taille sont encore très lacunaires. Il s'agit aujourd'hui d'identifier, à l'échelle du réseau hydrographique, l'origine, les conditions de mobilité et de transfert du bois mort, afin de mieux cibler les mécanismes et les secteurs de production et de stockage. Ces démarches devraient permettre à moyen terme de proposer des solutions adaptées en termes d'entretien des cours d'eau et de gestion des risques associés. Toutes ces questions se posent sur l'Isère à l'amont de Grenoble. Une démarche holistique est ainsi engagée dans le cadre de cette thèse à l'échelle de ce bassin. Elle s'est organisée autour de trois axes thématiques. Une première étape a consisté à parcourir les linéaires de l'Isère entre le barrage d'Aigueblanche et Grenoble, de l'Arc entre Saint-Jean-de-Maurienne et la confluence de l'Isère, de l'Arly entre Ugine et la confluence de l'Isère. Le résultat a permis de cartographier les différentes formes d'accumulation du bois mort le long du linéaire et d'identifier les zones préférentielles de dépôts (et inversement) ainsi que certains paramètres contrôlant la distribution spatiale des accumulations de bois mort le long de ce linéaire. La deuxième étape s'est appuyée sur les secteurs où de fortes concentrations en bois mort ont été déterminées. Sur ces sites, des mesures ont été réalisées sur les troncs stockés dans les chenaux des différents cours d'eau afin d'élaborer la carte d'identité des bois morts en transit. Trois tests méthodologiques ont ensuite été effectués afin d'identifier l'origine géographique des bois morts stockés dans le chenal de l'Isère à l'aval d'Albertville. La troisième étape présente les résultats issus d'un test de suivi des bois par traçage mis en place en 2002 et de l'expérimentation réalisée en juin 2003 lors d'un lâcher de barrage. Nous avons étudié ensuite la dynamique des bois morts en rapport avec l'hydrologie des cours d'eau. A partir des résultats obtenus, des propositions de gestion ont été formulées. Elles ont eu pour objectifs de réduire les risques d'inondations et de dommages au niveau des ouvrages et des zones urbaines, de réduire les coûts d'extraction et les contraintes d'exploitation aux barrages et aux ponts. Il s'agissait, en outre, de trouver une solution permettant d'éviter une systématisation de l'entretien sur tout le linéaire qui est financièrement et écologiquement coûteuse, et de proposer quelques règles permettant de promouvoir l'impact des politiques d'entretien mises en place.

Floodplain forests present a complex and diversified mosaic of vegetation units, which result from a combination of physical and temporal gradients, biotic interactions and human pressures. Qualitatively, the links between vegetation and hydro-morphological processes have been explored by several authors, but some aspects remain poorly documented (Chapter 1). In this thesis, we analyse, quantitatively, the impact of the hydro-morphological evolution of the channel on water and sediments fluxes, and thus on floodplain forests of Rhodanian hydrosystems. At first, a temporal framework for examining the vegetation dynamics during the second part of the 20th century is developed (Chapter 2). At the landscape scale (Chapter 2-A), human control is fundamental to both the evolution of the surfaces and the structural characteristics of the corridor. Thus, we show that abandonment of forestry and pastoral practices can lead to an increase in floodplain vegetation cover (Ain River). Conversely, human activities can reduce forested cover and lead to its fragmentation (Arve River). Where lateral channel mobility occurs, the diversity of the landscape mosaic is increased. However, we highlight a strong geographical decoupling between the internal zone of the corridor and the external one. Finally, the transitory nature of the structure and diversity are discussed. At the individual scale (Chapter 2-B), radial growth analysis of ash along the Rhône River and its tributaries also show that hydro-morphological and human processes are the dominant controls. The altitude of a site is the most important control on the degree of hydrological connection; on the Ain River a threshold has been identified between a flow of 750 m3.s-1 and 1000 m3.s-1. Furthermore, the spatial pattern of sediment deposits can greatly affect ash growth. Indeed, analysis of the root systems shows a double control: an edaphic control (pebble layer as an impenetrable horizon) and hydrologic control (high groundwater level). Obviously, process and pattern are strongly linked and our results show that bed mobility, by modifying topographical pattern connection and sediment dynamics, changes ecological conditions within the floodplain. In highly human-influenced systems, human activities alter the distribution of temporal and spatial fluxes.Second (Chapter 3), we worked at a smaller timescale and at the community level. For both the understory strata of post-pioneer forests of the Ain River (Chapter 3-A) and pioneer communities of Drôme River, we demonstrate that ecological conditions are influenced not only by the spatial position of a unit, but also by the geometrical evolution of the bed. This evolution depends on reach dynamics: bed mobility on the Ain River; embankment on the Drôme River. For riparian communities, contrasts in the degree of connection and disturbance result in different community composition, structure, regeneration and diversity. We highlight the role of fine sediment dynamics within forested ecosystems. Thus sediment erosion and deposition is a main process in term of disturbance impact. In pioneer communities, sediment grain size and thickness act as an important filter for ligneous species selection. We also show how fine sediment dynamics are controlled by reach-scale processes.The examples developed in this work show a geographical pattern of key factors linked with hydro-morphological conditions and human influences. They constitute a significant argument for promoting a consistent management strategy for fluvial systems and floodplain forests, with practices that consider the evolution of all hydrosystem components (bed, groundwater etc.). For this purpose, after noting the specificities of floodplain forests, a strategic framework is proposed that addresses the spatial coherence of forests, functional diagnosis, the choice of management, taking into account the hydro-morphological context, site rehabilitation, and the legal and financial tools available (Chapter 4). Finally, the results obtained within the framework of this thesis make it possible to discuss the concepts of physical connection (hydrological and morphological), human pressures, and riparian path (Conclusion)., L'effet combiné des gradients physiques, des interactions biotiques et des impacts anthropiques, le tout dans un cadre temporel évolutif, donne aux forêts alluviales l'aspect d'une mosaïque complexe où se juxtaposent, dans l'espace et dans le temps, des milieux variés et diversifiés. Si, depuis plus de trente ans, les études ont décrit, qualitativement, les liens qui unissent la végétation des plaines alluviales et la dynamique hydro-morphologique du chenal, certains aspects ont été peu abordés (Chapitre 1). C'est pourquoi, nous avons analysé, quantitativement, l'impact de l'évolution hydro-morphologique du chenal sur les flux d'eau et de sédiments et donc sur les boisements riverains dans les hydrosystèmes rhodaniens. Dans ce contexte, les contrôles anthropiques ont été explicitement intégrés dans l'analyse de l'évolution des structures et des flux. De fait, deux questions scientifiques ont été abordées.Dans un premier temps (Chapitre 2), une approche temporelle de la dynamique de la végétation riveraine à l'échelle de la seconde moitié du 20e s a été développée. Au niveau du paysage (Chapitre 2-A), le contrôle anthropique apparaît très important, aussi bien pour l'évolution des surfaces boisées, que pour la structuration spatiale du corridor naturel. Ainsi, nous avons montré que l'abandon des pratiques sylvicoles et pastorales peut être le moteur de la végétalisation des lits majeurs (Ain). A l'inverse, l'implantation de structures anthropiques dans le paysage réduit la superficie des milieux forestiers et provoque une fragmentation de l'ensemble du corridor (Arve). Lorsque la dynamique latérale du chenal peut s'exprimer, elle est à l'origine d'une plus grande diversité des unités paysagères. Cependant, nous avons mis en lumière un fort découplage géographique entre la dynamique de la zone interne du corridor et celle de la zone externe. Enfin, le caractère transitoire de la structure et de la diversité de la mosaïque paysagère a également été montré. A l'échelle des individus (Chapitre 2-B), l'analyse de la croissance ligneuse du frêne montre également que les contrôles hydro-morphologiques et anthropiques sont prépondérants pour la dynamique de la végétation riveraine à moyen terme. De fait, la position altitudinale d'une placette contrôle en grande partie son degré de connexion hydrologique ; sur l'Ain, un effet de seuil a pu être identifié pour la croissance du frêne entre des débits de connexion de 750 m3.s-1 et de 1000 m3.s-1. De plus, la structuration spatiale du substrat est également, pour le frêne, un facteur important contrôlant sa croissance radiale. L'analyse de la prospection racinaire de cette essence met en évidence un double contrôle au niveau du substrat : un contrôle édaphique (présence d'horizons impénétrables, ex. : le toit de galets) et un contrôle hydrologique (présence d'une nappe permanente ou semi-permanente). Evidemment, structure et fonctionnement sont intimement liées et nos résultats indiquent que la mobilité du chenal, en modifiant de façon significative le patron hydrologique et sédimentaire, affecte les conditions écologiques au sein de la plaine. De même, dans les corridors riverains soumis à une pression anthropique importante, le développement d'activités consommatrices d'eau entraîne une modification de la répartition spatiale et temporelle des flux au sein de l'hydrosystème. Dans un deuxième temps (Chapitre 3), nous avons travaillé à une échelle de temps plus courte et à l'échelle spatiale de la communauté végétale. Dans la strate basse des boisements post-pionniers (frênaie) du corridor de l'Ain (Chapitre 3-A) aussi bien que dans les unités pionnières (saulaies) de la Drôme (Chapitre 3-B), nous avons montré que les conditions écologiques d'une unité varient non seulement en fonction de sa position dans l'hydrosystème à un instant donné, mais aussi au gré de l'évolution de la géométrie du chenal. Cette évolution résulte de l'ajustement aux conditions de débits, solide et liquide, au sein du chenal ; elle est donc liée à la dynamique de l'ensemble du tronçon fluvial : mobilité du chenal (incision sur l'Ain), effet des aménagements anthropiques (endiguement sur la Drôme). Concernant les communautés végétales, la position spatiale et la dynamique du tronçon se traduisent par des niveaux contrastés de connexion hydro-sédimentaire et donc de régime de perturbation. L'expression des processus hydrologiques et sédimentaires se répercute ainsi sur la communauté, en termes de composition, de structure, de régénération ou de diversité. Le rôle important joué par la dynamique des sédiments fins dans les forêts alluviales est alors souligné par nos résultats. En effet, l'érosion et le dépôt de sédiments constituent les processus primordiaux du caractère perturbant d'une crue. De plus, la granulométrie et l'épaisseur du substrat constituent un filtre à l'origine d'une sélection des espèces arbustives dans les milieux pionniers. Notons que cette dynamique des sédiments fins est sous le contrôle de la dynamique hydro-morphologique de l'ensemble du tronçon. Les exemples développés dans notre travail font apparaître une véritable géographie des facteurs de contrôle liée à l'expression différenciée des conditions hydro-morphologiques mais aussi une empreinte anthropique toujours présente. Par exemple, l'influence de la mobilité du chenal sur la croissance et la régénération ligneuse ainsi que le contrôle exercé par la dynamique sédimentaire sur le paysage et les communautés riveraines constituent des arguments importants pour développer une gestion cohérente des lits fluviaux et de leurs marges boisées. Pour cela, après avoir rappelé la spécificité des boisements alluviaux, nous proposons des éléments stratégiques de gestion, concernant notamment : la cohérence géographique des boisements à gérer, le diagnostic fonctionnel de ces forêts, le choix des objectifs de gestion, la prise en compte du contexte hydro-morphologique et de son évolution, la réhabilitation des sites et la cohérence des outils législatifs et financiers permettant d'agir dans ce domaine (Chapitre 4).Enfin, les résultats obtenus dans le cadre de cette thèse permettent de discuter les notions de connexion physique (hydrologique et sédimentaire), de contraintes anthropiques et de trajectoire écologique (Conclusion).

In the context of recent work by Brocchini & Peregrine [1,2], this paper aims to document free surface profiles, and turbulence length scales in hydraulic jumps with Froude numbers between 1.98 and 4.82. Although information on bubble size, frequency and velocities in hydraulic jumps is available in the literature, there is not much data on the features of the free surface, or on mixing layer thickness. In the present case, measurements at the free surface have been realized with two miniature resistive wire gauges each comprising two parallel 50 micron diameter wires with a separation of 1mm. These instruments were calibrated dynamically over a range of frequencies up to 20 Hz. Furthermore optical probes were used to measure properties of the air phase within the jump, including void fractions (up to 98%). The present results extend the range of Froude numbers for which two-phase measurements in hydraulic jumps are available, and, in most respects, confirm earlier results obtained with different experimental techniques. Length scales at the free surface are deduced from cross-correlation analysis of wire gauge measurements, and are compared with similar data obtained from images of the surface.Copyright © 2004 by ASME

Very high-resolution seismic data was acquired along the microtidal wave-dominated littoral zone of the western Gulf of Lions (SE France) with a view to estimate the volume of sand present in the upper shoreface under conditions of stable high sea level. An upper sand unit is thus identified at the top of the shoreface, bound at its base by a hard floor made of beach-rock layers or geological substrate. This upper sand unit (USU) is mobile and represents the available sand stock used for internal exchanges and beach supply. Estimate of the USU volume takes place within each sedimentary compartment and cell defined along the littoral zone. Two main results are obtained from this quantification. (1) The distribution of the sand stock fits with the littoral drift pattern, updrift source zones being characterized by low volume USU, while downdrift sink areas are characterized by much larger sand reservoirs. This distribution pattern is verified at all scales, the regional, the compartment and the cell scales; (2) the volume of the upper shoreface sand reservoir seems to match the adjacent beach behaviour. Wherever the beach evolution trend is negative, the stock is depleted and, on the contrary, the beaches associated to voluminous reservoirs do not suffer erosion.

International audience; The structural evolution of the English Channel area is controlled by structure and particularly by the pre-existing Cadomian and Variscan crustal discontinuities, which have been reactivated repeatedly in post-Variscan times. They controlled the crustal subsidence that produced basin development in the Mesozoic, prior to the sea-floor spreading in the North Atlantic region. They were then reactivated during the Cenozoic compression and basin inversion. The English Channel development is ascribed to mid-Tertiary differential uplift (Oligocene to Miocene). During late Tertiary to Quaternary times the Channel displays characteristics of a tectonically controlled fluvial basin periodically invaded by the sea. At the lithospheric scale, the Channel can be considered as an active intraplate area influenced by the NW–SE ‘Alpine push', the NW–SE ‘Atlantic ridge push' and glacial rebound stresses.

National audience

The degradation of the Jobourg fault-scarp occurred by cryoclastic processes in a periglacial environment during a part of Quaternary time. An attempt of quantification indicates a bulk scarp erosion of about 39 m 3 m −2 , while the head accumulated at the bottom of the fault scarp only represents 4.6 m 3 m −2 . To cite this article: M. Font et al., C. R. Geoscience 334 (2002) 171–178.

le pdf ne reproduit pas exactement la mise en page du mémoire; The study of the Zagros chain is envisaged under three different aspects, with in the first place a step on paleoenvironnement, in the second place a hydroclimatic approach, and finally an analysis of relationships between man and karst. Relation ships between three tectonic zones of the Zagros are envisaged to retrace its morphological evolution. For this, three zones of studies have been retained : Alisadr to the north of Hamadan, Kuh-e-Garrin to the south of Nahavand and Sabz Poshan to the south of Shiraz. From geological and geomorphological indices preserved by the immunization karst, confronted with endokarst indices, the paleoenvironnement and paleoclimatic evolution of these mountains can be retraced in order to specify the general evolution of the Zagros. The study is approached by the synthesis of a large variety of indices observed at different scales. More over, different paleoenvironnement indices are apprehended by means of analytic sedimentologic techniques and physico-chemical analysis (mineralogical clay analysis and sands, concretions lamina analysis, texture analysis, calcareous mesurement, sands morphoscopy, soil densimetry, datings with microfossils and datings with isotopics).This study is also associated to a precise characterization of the current hydroclimatic fonctioning of Zagros mountains in order to better understand their current evolution. Thus precipitations, that still remain not well appreciated in the total area of the Zagros, are apprehended at different spacial and temporal scales : scale of the Zagros and that of an endoreic of 4000 km² (region of Shiraz) with also the use of a pluviometric model (PLUVIA). The water balance of this basin is then approached more precisely with the modeling of variations of its water level. The hydrochemical balance and notably the specific dissolution of the three study zones are also apprehended. Finally the analysis of the adaptation of local populations to the karst is presented through two different axes : the study of lours nomads and qanat (SW of Shiraz).; L'étude de la chaîne du Zagros est envisagée sous trois aspects différents avec successivement une démarche paléoenvironnementale, une approche hydroclimatique et une analyse des relations entre l'homme et l'environnement karstique. Les relations entre les trois zones tectoniques du Zagros sont appréhendées pour retracer son évolution morphologique. Pour cela, trois zones d'études ont été retenues : celle d'Alisadr au nord d'Hamadan, celle du Kuh-e-Garrin au sud de Nahavand et celle du Sabz Poshan au sud de Shiraz. A partir d'indices géologique et géomorphologique, bien conservés par l'immunisation karstique, confrontés à des informations endokarstiques, l'évolution paléoenvironnementale et paléoclimatique de ces massifs peut être retracée et permet ainsi de préciser l'évolution générale du Zagros. L'étude est abordée par la synthèse d'une grande variété d'indices observée à différentes échelles. De plus, différents marqueurs paléoenvironnementaux sont mis en lumière par le biais de techniques analytiques sédimentologiques et physico-chimiques (analyse minéralogique des argiles et des sables, analyse des lamines des concrétions, analyse texturale, calcimétrie, morphoscopie des sables, densimétrie des sols, datations avec les microfossiles et datations isotopiques...).Cette étude est aussi associée à une caractérisation précise du fonctionnement hydroclimatique actuel des massifs du Zagros afin de mieux cerner leur karstogenèse actuelle. Ainsi les précipitations, qui restent encore aujourd'hui mal appréciées et peu connues sur l'ensemble du Zagros, sont appréhendées à différents niveaux d'échelles spatiales et temporelles : à l'échelle du Zagros et à l'échelle d'une cuvette endoréique de 4 000 km² (région de Shiraz) avec alors l'utilisation d'un modèle pluviométrique (PLUVIA). Le bilan hydrologique de cette cuvette est ensuite abordée de manière plus précise avec la modélisation des variations de son plan d'eau. Le bilan hydrochimique et notamment la dissolution spécifique des trois zones d'études sont aussi précisés.Enfin l'adaptation des populations locales au milieu naturel karstique est présentée à travers deux axes différents : l'étude des nomades lours et l’étude d'un qanat (SW de Shiraz).

International audience; Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile's deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan 'depeopling', reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction. Citation: Marriner N, Flaux C, Morhange C, Stanley J (2013) Tracking Nile Delta Vulnerability to Holocene Change. PLoS ONE 8(7): e69195.

The Magdalenian occupation levels at Grand Canton and Tureau des Gardes at Marolles-sur-Seine (Seine-et-Marne) fit perfectly into the regional Lateglacial context - from late Boiling to early Alleród. Both technologically and typologically, the lithic industry indicates a close relationship between these two sites and with the « classical » sites of the region, in particular Marsangy. The topography and large quantity of bones found suggest these were hunting sites, specialised in horse- hunting. Although it is difficult to decide whether there was a single occupation or periodic reoccupation of the sites, it seems reasonable to consider these two sites not as mere hunting halts, but as places where activities were carried out for later consumption., RESUME Les occupations magdaléniennes du Grand Canton et du Tureau des Gardes, à Marolles-sur-Seine (Seine-et-Marne), s'intègrent parfaitement dans le contexte régional du Tardiglaciaire, de la fin du Boiling au début de l'Allerôd. Technologiquement et typologiquement, l'industrie lithique dénote une étroite parenté entre ces deux sites et avec les sites « classiques » de la région, en particulier Marsangy. La topographie et l'abondance des restes osseux permettent de penser à des sites de chasse, spécialisés sans doute dans la chasse au cheval. S'il est difficile de trancher entre une occupation unique et une réoccupation périodique des sites, il paraît fondé de voir dans ces deux gisements non pas de simples haltes de chasse, mais des lieux d'activités effectuées pour une consommation différée., Alix Philippe, Averbouh Aline, Binter Laurent, Bodu Pierre, Boguszewski Andrzej, Cochin Christine, Deloze Valérie, Gouge Patrick, Krier Vincent, Leroyer Chantal, Mordant Daniel, Philippe Michel, Rieu Jean-Luc, Rodriguez Patrick, Valentin Boris. Nouvelles recherches sur le peuplement magdalénien de l'interfluve Seine-Yonne. Le Grand Canton et Le Tureau des Gardes à Marolles-sur-Seine (Seine-et-Marne). In: Bulletin de la Société préhistorique française, tome 90, n°3, 1993. pp. 196-218.

Most of the experimental work carried on pile behavior on centrifuge has been limited to monotonic or cyclic loading, or both. As dynamic loads generated by shocks and earthquakes are difficult to model in centrifuge, not much work has been reported in the literature on the impact mechanism to produce shock in-flight, though seismic loads can be well simulated by in-flight shakers. A complete experimental procedure, i.e., hammering system, measurements, and test procedures, has been developed to test on centrifuge lateral impact on piles. In the first part of the paper following the test procedure, the experimental set-up is detailed from the soil preparation and piles equipment to the horizontal hammering or impact system. Innovative parts of the system such as the impact system and its monitoring are described. The second part describes the feasibility and the practice of the impact device and the adopted procedure to test on centrifuge different types of piles _jacked, cast-in, and 1 g driven_ in sand. The first series of tests are focused on the evaluation of possible errors and influences due to pile position, boundary effects, and repeatability of tests. Scale effects have been studied by carrying out a series of modeling of models tests at 40 and 60 g. In conclusion, all these preliminary centrifuge tests have demonstrated that the complete experimental set-up including the impact system and its use procedure is achieved and able to perform horizontal impacted piles tests on centrifuge.

International audience; Evolution of tidal inlets or river outlets has been widely described all over the world. However, most conceptual models are based on the long term perspective and field measurements to confirm these evolution schemes are scarce. The objective of the present study is to quantify the processes occurring at a small river outlet, the Bevano, during fair weather conditions. Subtidal fluorescent sand tracer method involving a new detection tool were used in the inlet and along the adjacent coast to assess sediment transport and bypassing processes. At the river mouth, sediment fluxes confirm an efficient bypass of sand through the inlet's channel. However, this sediment transport is combined with migration processes of the channel (40min 2 months), and yields a self-alimentation of both updrift and downdrift coasts. As it has already been observed at small tidal inlets, migration of the Bevano river mouth results from the erosion of the downdrift coast, and readjustment of the cross-section by the longshore transport on the updrift coast. The detection device used for subtidal tracing has given encouraging results and will be improved in order to work in more dynamic environments.

International audience; This work aims to better understand the physical processes governing the wave propagation in a vertically shearedcurrent and the resulting nearshore circulation patterns. It is based on a high resolution hydro-morphodynamic fieldcampaign, ROUSTY2014, collecting a comprehensive hydro-morphodynamical dataset during a full winter season.The overall analysis highlights three main circulation patterns, largely controled by the bathymetric features and byco-working or competing wind and waves forcings. Regarding the vertical structuration of the circulation, most of fieldobservations shown seaward directed circulation with onshore component close to the air/sea surface whose intensityvaries according to incoming wave conditions. Forth, vertical shear increase when breaking happen close to sensorlocation and orientation of mean circulation depend on wind direction.