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| Registros recuperados: 23 | |
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| Jaud, Marion; Letortu, Pauline; Augereau, Emmanuel; Le Dantec, Nicolas; Beauverger, Mickael; Cuq, Veronique; Prunier, Christophe; Le Bivic, Rejanne; Delacourt, Christophe. |
| The georeferencing process is crucial to the accuracy of terrestrial laser scanner (TLS) data, in particular in the context of diachronic studies relying on multi-temporal surveys. The use of Ground Control Points in the georeferencing process can however be complex when confronted with the practical constraints of coastal surveying. A simple and quick alternative method called "pseudo-direct georeferencing" is proposed in the present paper. This method involves internal inclinometers to measure roll and pitch angles and a centimetric GPS to measure the position of the TLS center and the position of one backsight target. When assessing the transformational uncertainty by using a set of independent ground validation points for both classical indirect and... |
| Tipo: Text |
Palavras-chave: Terrestrial laser scanning; Coastal monitoring; Direct georeferencing; Indirect georeferencing; Multi-temporal surveys; Geomorphological evolution. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75050/75683.pdf |
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| Moussa, N.; Boiron, M.c-; Grassineau, N.v.; Asael, Dan; Fouquet, Yves; Le Gall, Bernard; Rolet, Joël; Etoubleau, Joel; Delacourt, Christophe. |
| In this paper, the mineralogy, fluid inclusions and stable isotopes of hydrothermal veins from the SE part of the Afar Rift (Djibouti) were studied. Mineralization occurs as gold-silver in quartz/carbonate veins and is mainly associated with felsic volcanism. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions. Mean homogenization temperature ranges from 150°C to 340°C and ice-melting temperatures range from -0.2°C to - 1.6°C indicating that inclusion solutions contain 0.35 to 2.7 eq. wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3 ‰, respectively. The presence of... |
| Tipo: Text |
Palavras-chave: Fluid inclusions; Stable isotopes; Hydrothermal; Epithermal system; SE Afar Rift; Djibouti. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60528/63991.pdf |
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| Mazuel, Aude; Sisavath, Emmanuelle; Babonneau, Nathalie; Jorry, Stephan; Bachelery, Patrick; Delacourt, Christophe. |
| Recent marine geophysical surveys reveal the existence of well-developed volcaniclastic deep-sea fans around La Réunion Island, Indian Ocean. The Mafate turbidite complex, located in the northwestern part of the island, is a large sedimentary system formed by two coalescent-like volcaniclastic deep-sea fans: the Mafate fan and the Saint-Denis fan. They are both connected to terrestrial rivers supplying sediment produced by erosion on the island, particularly during austral summer cyclonic floods. Through the integration of marine geophysical data (including bathymetry, backscatter multibeam sounder images, TOBI side-scan sonar images and seismic reflection profiles) and piston cores, a submarine morpho-sedimentary map of the surface architecture of the... |
| Tipo: Text |
Palavras-chave: Deep-sea fan; Turbidite; Volcaniclastic; Land-to-sea transfer; La Reunion Island; Late Quaternary. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00312/42273/41597.pdf |
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| Fromant, G.; Floc'H, F.; Lebourges-dhaussy, Anne; Jourdin, F.; Perrot, Yannick; Le Dantec, N.; Delacourt, Christophe. |
| The study of the suspended particulate matter (SPM) transport is essential to understanding oceans and rivers, for their presence can impact the environment, from marine habitats or water quality degradations to important changes of the seabed morphology. Among a large number of surrogate techniques in traditional water sampling, acoustical methods have the advantage of providing nonintrusive measurements, with high spatial and temporal resolutions. However, the ability of fine-grained sediments to aggregate under the process of flocculation complexifies the interpretation of acoustical measurements. The objective of this paper is to design a simple backscatteringmodel for flocculated sediment suspensions, in order to interpret the information provided by... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00616/72809/72590.pdf |
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| Babonneau, Nathalie; Delacourt, Christophe; Cancouet, R.; Sisavath, Emmanuelle; Bachelery, Patrick; Mazuel, Aude; Jorry, Stephan; Deschamps, Anne; Ammann, Jerome; Villeneuve, N.. |
| Submarine canyon heads are key areas for understanding the triggering factors of gravity currents responsible for the transfer of detrital sediment to the deep basins. This contribution offers a detailed picture of canyon heads off La Réunion Island, with high-resolution multibeam bathymetry in the water depth range of 4–220 m. The present feeding of the Cilaos turbidite system, one of the largest modern volcaniclastic systems in the world, is deduced from morphological and sedimentological interpretations of newly acquired data. The study highlights small-scale sedimentary features indicating hydrodynamic and sedimentary processes. A direct connexion between the Saint-Etienne river mouth and submarine canyons is evidenced by the complete incision of the... |
| Tipo: Text |
Palavras-chave: Submarine canyon; Canyon head; Turbidity current; Hyperpycnal flow; Coastal instability. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00156/26697/24790.pdf |
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| Jaud, Marion; Kervot, Matthieu; Delacourt, Christophe; Bertin, Stephane. |
| With recent advances in photogrammetric processing methods and sensor technologies, smartphones represent a new opportunity of mainstream, low-cost sensor, with a great potential for Structure-from-Motion (SfM) photogrammetry, and in particular for participatory science programs or citizen observatories. Keeping in mind the application in citizen observatories, three smartphone models (Galaxy S7 (R), Lumia 930 (R) and iPhone 8 (R)) and a bridge camera were compared (separately and in combination) for coastal applications: A coastal cliff and a sandy beach. Various acquisition protocols, at different distances from a cliff face and using "linear" or "fan-shaped" capture mode, were also assessed in their efficiency. A simultaneous Terrestrial Laser Scanner... |
| Tipo: Text |
Palavras-chave: Smartphone; SfM photogrammetry; Coastal monitoring; DEM; Citizen observatory. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74907/76115.pdf |
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| Jaud, Marion; Grasso, Florent; Le Dantec, Nicolas; Verney, Romaric; Delacourt, Christophe; Ammann, Jerome; Deloffre, Julien; Grandjean, Philippe. |
| Intertidal mudflats play a critical role in estuarine exchange, connecting marine and continental supplies of nutrients and sediments. However, their complex morphodynamics, associated with a wide range of physical and biological processes, are still poorly understood and require further field investigation. In addition, mudflats are challenging areas for Structure-from-Motion (SfM) photogrammetric surveys. Indeed, the mudflats generally hold back residual tidal water, which can make stereo restitution particularly difficult because of poor correlations or sun-glint effects. This study aims to show the potential of light UAVs (Unmanned Aerial Vehicles) for monitoring sedimentary hydrodynamics at different spatial scales in a silty estuary. For each UAV... |
| Tipo: Text |
Palavras-chave: Coastal monitoring; Unmanned Aerial Vehicle; Photogrammetry; Estuary; Mudflat areas; Morphological features. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00326/43721/43167.pdf |
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| Jaud, Marion; Delacourt, Christophe; Le Dantec, Nicolas; Allemand, Pascal; Ammann, Jerome; Grandjean, Philippe; Nouaille, Henri; Prunier, Christophe; Cuq, Veronique; Augereau, Emmanuel; Cocquempot, Lucie; Floc'H, France. |
| In the dual context of coastal hazard intensification and the growing number of stakes exposed to these hazards, coastal observatories are in demand to provide a structured framework dedicated to long-term monitoring. This article describes the drone-based photogrammetry monitoring performed since 2006 on Porsmilin Beach (Brittany, France) in the framework of the DYNALIT (Littoral and Coastline Dynamics) observatory, focusing on data quality and the consistency of long-term time series under the influence of multiple technological evolutions: Unmanned Aerial Vehicles (UAV) platforms with the arrival of electric multirotor drones, processing tools with the development of structure-from-motion (SfM) photogrammetry, and operational modes of survey. A study... |
| Tipo: Text |
Palavras-chave: UAV; SfM photogrammetry; Coastal observatory; Beach monitoring. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74927/76116.pdf |
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| Stumpf, A.; Delacourt, Christophe; Malet, J. P.. |
| The increasing fleet of VHR optical satellites (e.g. Pleiades, Spot 6/7, WorldView-3) offers new opportunities for the monitoring of surface deformation resulting from gravitational (e.g. glaciers, landslides) or tectonic forces (coseismic slip). Image correlation techniques have been developed and successfully employed in many geoscientific studies to quantify horizontal surface deformation at sub-pixel precision. The analysis of time-series, however, has received less attention in this context and there is still a lack of techniques that fully exploit archived image time-series and the increasing flux of incoming data. This study targets the development of an image correlation processing chain that relies on multiple pair-wise matching to exploit the... |
| Tipo: Text |
Palavras-chave: Deformation measurement; Image correlation; High-performance computing; Satellite remote sensing. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00639/75146/75512.pdf |
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| Jaud, Marion; Passot, Sophie; Le Bivic, Rejanne; Delacourt, Christophe; Grandjean, Philippe; Le Dantec, Nicolas. |
| For monitoring purposes and in the context of geomorphological research, Unmanned Aerial Vehicles (UAV) appear to be a promising solution to provide multi-temporal Digital Surface Models (DSMs) and orthophotographs. There are a variety of photogrammetric software tools available for UAV-based data. The objective of this study is to investigate the level of accuracy that can be achieved using two of these software tools: Agisoft PhotoScan((R)) Pro and an open-source alternative, IGN((c)) MicMac((R)), in sub-optimal survey conditions (rugged terrain, with a large variety of morphological features covering a range of roughness sizes, poor GPS reception). A set of UAV images has been taken by a hexacopter drone above the Riviere des Remparts, a river on... |
| Tipo: Text |
Palavras-chave: Image processing; SfM photogrammetry software; Digital Surface Model; UAV; Orthophoto; Accuracy assessment. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00639/75081/75581.pdf |
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| Cocquempot, Lucie; Delacourt, Christophe; Paillet, Jerome; Riou, Philippe; Aucan, Jérôme; Castelle, Bruno; Charria, Guillaume; Claudet, Joachim; Conan, Pascal; Coppola, Laurent; Hocdé, Régis; Planes, Serge; Raimbault, Patrick; Savoye, Nicolas; Testut, Laurent; Vuillemin, Renaud. |
| To understand and predict the physical, chemical, and biological processes at play in coastal and nearshore marine areas requires an integrated, interdisciplinary approach. The case study of the French structuration of coastal ocean and nearshore observing systems provides an original overview on a federative research infrastructure named ILICO. It is a notable example of national structuration and pan-institution efforts to investigate the forefront of knowledge on the processes at work within the critical coastal zone. ILICO comprises, in a pluridisciplinary approach, eight distributed network-systems of observation and data analysis that are accredited and financially supported by French research institutions and the French Ministry for Higher... |
| Tipo: Text |
Palavras-chave: Observation infrastructure; National structuration; Interdisciplinary; Coastal ocean; Coastline. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00503/61489/65292.pdf |
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| Van Vliet-lanoe, Brigitte; Goslin, Jerome; Henaff, Alain; Hallegouet, Bernard; Delacourt, Christophe; Le Cornec, Erwan; Meurisse-fort, Murielle. |
| Holocene coastal dune formation under a continuously rising sea level (SL) is an abnormal response to increasing storm frequency. The aim of this work is to understand the coastal sedimentary budget and the present-day sand starvation, controlled by climate and man. Dating in Brittany shows that Aeolian deposition initiated from ca. 4000 cal BP, with the slowing down of the SL rise. Pre-historical dunes appeared here from ca. 3000 cal BP, without SL regression. After, further building phases recycled the same stock of sands. Historical dunes I developed from ca. 350 AD. Major storms between 900 and 1200 AD resulted in the construction of washover coastal ridges, the Historical dunes II. A part of the sand was evacuated offshore. From ca. 1350 AD, the... |
| Tipo: Text |
Palavras-chave: Dunes; Holocene; Climate; Sand starvation; Anthropic perturbation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00591/70262/68321.pdf |
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| Didier, David; Bernatchez, Pascal; Augereau, Emmanuel; Caulet, Charles; Dumont, Dany; Bismuth, Eliott; Cormier, Louis; Floc'H, France; Delacourt, Christophe. |
| Increasingly used shore-based video stations enable a high spatiotemporal frequency analysis of shoreline migration. Shoreline detection techniques combined with hydrodynamic conditions enable the creation of digital elevation models (DEMs). However, shoreline elevations are often estimated based on nearshore process empirical equations leading to uncertainties in video-based topography. To achieve high DEM correspondence between both techniques, we assessed video-derived DEMs against LiDAR surveys during low energy conditions. A newly installed video system on a tidal flat in the St. Lawrence Estuary, Atlantic Canada, served as a test case. Shorelines were automatically detected from time-averaged (TIMEX) images using color ratios in low energy conditions... |
| Tipo: Text |
Palavras-chave: Video monitoring; Shoreline detection; Beach morphology; Mobile terrestrial LiDAR; Erosion; Atlantic Canada. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75022/75656.pdf |
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| Mahabot, Marie-myriam; Jaud, Marion; Pennober, Gwenaelle; Le Dantec, Nicolas; Troadec, Roland; Suanez, Serge; Delacourt, Christophe. |
| Under natural and anthropogenic pressure, the coastal regions are evolving rapidly (population growth, erosion, modification of services, etc.), and some of these changes increase their vulnerability. Monitoring the evolution of the coastal regions has thus become essential to understand how they respond to the various pressures and to define how their resilience could be increased. Among other outcomes, such monitoring should provide continuous, high-resolution data on the spatial and temporal evolution of the coastal areas, especially the shoreline zone. One appropriate way to acquire long, continuous, time series of data is to set up a permanent observatory in the zone to be monitored. This paper aims to provide recommendations and a methodological... |
| Tipo: Text |
Palavras-chave: Carbonate beaches; Coral reef; Coastal observatory; UAV; TLS; Bathymetric Lidar. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75013/75695.pdf |
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| Garnier, Josette; Castelle, Bruno; Labille, Jérôme; Souchu, Philippe; Thieu, Vincent; Delacourt, Christophe. |
| L’interface entre l’atmosphère et les surfaces continentales est un lieu d’échanges importants d’énergie et de matière liquide, solide ou gazeuse. Aussi, comprendre et quantifier les interactions entre surfaces et atmosphère est un enjeu de premier ordre pour essayer d’anticiper au mieux les conséquences de nouvelles et futures évolutions des surfaces continentales, que ce soit sous l’effet de l’évolution du climat ou de modifications de l’usage des sols. Des processus spécifiques se produisent à l’interface surface-atmosphère, rendant nécessaire l’étude de cette interface non comme un simple lieu de transfert, mais en tant qu’objet propre. S’attacher à identifier et quantifier les processus opérant dans le continuum sol-eau-plante-atmosphère doit... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00603/71464/69919.pdf |
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| Le Bivic, Rejanne; Allemand, Pascal; Quiquerez, Amelie; Delacourt, Christophe. |
| Over the last 10 years, the accessibility of high spatial resolution remote sensing images has strongly increased. These images are available in ortho-rectified format which do not necessitate any further geometrical processing to be analyzed. In parallel, image correlation software has become more efficient and friendly. In this paper, image correlation methods are tested to evaluate their potential and limitations to measure the surface displacements in a complex case of a landslide located in a tropical environment. This studied landslide, called "Mare a Poule d'Eau", is located in the Salazie erosion watershed in Reunion Island (France). This landslide is monitored daily by a DGPS station which registers the south-north displacements. Two pairs of... |
| Tipo: Text |
Palavras-chave: SPOT-5; Image correlation; Landslide; Reunion Island. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75042/75670.pdf |
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| Le Goff, Ronan; Ropert, Michel; Bajjouk, Touria; Bein, Aymeric; Cambert, Harold; Cebeillac, Alexandre; Cuet, Pascale; Delacourt, Christophe; Duval, Magali; Maurel, Laurence; Mouquet, Pascal; Nicet, Jean Benoit; Populus, Jacques; Quod, Jean-pascal; Talec, Pascal; Turquet, Jean; Vermenot, Coralie; Zubia, Mayalen. |
| Le présent document est le rapport final du projet "Bio-Indication à la Réunion ; contribution à la définition d’indicateurs adaptés aux platiers récifaux de la Réunion". Ce projet comprend deux volets : Volet 1 : définition d’indicateurs d’enrichissement en nutriments (dystrophie) adaptés aux platiers récifaux réunionnais. Une importante phase d’acquisition de données de terrain portant sur les algues, les cyanobactéries, le corail, la faune associée et les caractéristiques hydrologiques des différents secteurs retenus a été menée entre fin 2010 et fin 2011 sur une année hydrologique complète afin d’essayer de bâtir des indicateurs d’état DCE adaptés aux masses d’eau récifales de la Réunion, et plus précisément des indicateurs de dystrophie. Ce volet... |
| Tipo: Text |
Palavras-chave: Habitats benthiques des platiers récifaux réunionnais; Indicateurs d’enrichissement en nutriments ou de dystrophie; Algues; Corail; Cartographie; Zone intertropicale; La Réunion; Océan Indien; DCE. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00209/32022/30459.pdf |
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| Registros recuperados: 23 | |
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