Search

Your search keyword '"Emmanuel Malet"' showing total 86 results
Start Over Author "Emmanuel Malet"
86 results on '"Emmanuel Malet"'

1. Ice aprons on steep high-alpine slopes: insights from the Mont-Blanc massif, Western Alps

Author

Ludovic Ravanel, Grégoire Guillet, Suvrat Kaushik, Susanne Preunkert, Emmanuel Malet, Florence Magnin, Emmanuel Trouvé, Maurine Montagnat, Yajing Yan, and Philip Deline

Subjects
Cold ice, glacial heritage, ice aprons, ice melting, Mont-Blanc massif, Environmental sciences, GE1-350, Meteorology. Climatology, QC851-999
Abstract

Ice aprons are defined as very small ice bodies covering steep rock slopes. They have only been the subject of increased scientific interest for a few years, despite the fact that they are a condition for mountaineering and obvious elements in the high-alpine landscapes. However, very little is known about their distribution, evolution and physical characteristics. In this paper, we review the existing knowledge on ice aprons, which have almost exclusively been investigated in the Mont-Blanc massif, Western Alps. We supplement this review with novel results from recent surveys of ice aprons. We used a wide array of methodologies, from remote sensing (multi-source imagery) to in situ (stakes and thermal monitoring) and laboratory (radiocarbon dating and texture analysis) glaciological investigations. In the Mont-Blanc massif, ice aprons occupy 4.2 km2 within the alpine permafrost zone. Temperature measured at the ice–rock interface is indeed largely negative. Thinness of ice aprons coupled with the cold context implies a quasi-stationary shear regime without basal Sliding. Only ice at the surface can possibly melt in warm periods. After a shrinking period from the end of the Little Ice Age to the mid-to-late-1960s, ice aprons experienced a short period of expansion, followed by an accelerated shrinkage since the beginning of the 21st century. This shrinkage now favours rockfall triggering and poses a serious threat to a glaciological heritage since ice aprons host several-thousand-year-old ice. Finally, we synthesize this information to assess the existing definition of ice aprons, and propose some future research directions.

Published
2023
Full Text
View/download PDF

2. Temporal Consolidation Strategy for Ground-Based Image Displacement Time Series: Application to Glacier Monitoring

Author

Guilhem Marsy, Flavien Vernier, Emmanuel Trouve, Xavier Bodin, William Castaings, Andrea Walpersdorf, Emmanuel Malet, and Blaise Girard

Subjects
Displacement measurement, glacier monitoring, photogrammetry, time series analysis, Ocean engineering, TC1501-1800, Geophysics. Cosmic physics, QC801-809
Abstract

In this article, we present a method for combining image-based displacements to build time series. This method takes advantage of the redundancy of these displacements, which comes from multiple possible combinations between images. The proposed method combines common master series with a different master date to construct a single time series of relative displacements. We were able to test this method on displacements computed using images from a stereo time-lapse device recording images of the Argentière glacier during the summer and fall of 2019. Our method was compared to two other displacement aggregation strategies: a simple common master approach and the classical inversion method. In order to perform this comparison, displacement data from four permanent GPS are used. The results show that our method provides a more accurate time series of relative displacements than those obtained with the other methods. The higher accuracy of the proposed method makes the detection of seasonal variations in glacier velocity possible.

Published
2021
Full Text
View/download PDF

3. A tribute to Bruno Wilhelm’s legacy in reading the geological record of lakes

Author

Fabien Arnaud, Pierre Sabatier, Jérôme Poulenard, Charline Giguet-Covex, Jean-Philippe Jenny, Erwan Messager, Jean-Jacques Delannoy, Emmanuel Malet, Cécile Pignol, Françoise Allignol, and Bruno Wilhelm

Abstract

On April 7th 2022 we learnt the devastating news: our friend and colleague, Bruno Wilhelm, had passed in the mountain while ascending a steep slope in the aim of skiing it. One year after, our group, within which he came and grow to science up to the defence of his PhD thesis in 2012, is still graving. In that context, we are grateful to the organisers of this session for offering us the opportunity of reminding our scientific community the multiple advancements it owes to Bruno.Bruno Wilhelm indeed did a hard and innovative work in the aim of reading the geological record of lakes. He focused himself on the recording of extreme events in lake sediments. In this keynote, we will emphasize how Bruno proposed original ways of characterising what we call “instant deposits”, mostly in the early stages of his too short career. He then particularly worked the question of distinguishing among triggering factors of those “alien” layers that often interbed within lake sediment calm sedimentation. Bruno also proposed a detailed reflexion aiming at quantifying or, at least, ranking the intensity of those triggering events. He hence proposed several ways of assessing past floods intensity. In the same spirit, he explicitly proposed a procedure to assess the “recordability” of past earthquake events within a given lake system, based on historical chronicles. He also led a common reflexion about the ability of lake sediment to record a regional flood signal. After his PhD he committed himself in the scientific animation of the PAGES’ “Floods” working group which led him to coordinate the establishment of a comprehensive database and to participate in the redefinition of a collaborative work to better understand past flood patterns in the iam of anticipating future changes due to global warming.It is undeniable that Bruno Wilhelm had a brilliant and far too short career. However, with this speech we hope that the community will be even more aware about the important legacy he left us.

Published
2023
Full Text
View/download PDF

4. Estimating surface water availability in high mountain rock slopes using a numerical energy balance model

Author

Matan Ben-Asher, Florence Magnin, Sebastian Westermann, Emmanuel Malet, Johan Berthet, Josué Bock, Ludovic Ravanel, and Philip Deline

Abstract

Water takes part in most physical processes that shape the mountainous periglacial landscapes and initiation of mass wasting. An observed increase in rockfall activity in several mountainous regions was previously linked to permafrost degradation in high mountains, and water that infiltrates into rock fractures is one of the likely drivers of these processes. However, there is very little knowledge on the quantity and timing of water availability for infiltration in steep rock slopes. This knowledge gap originates from the complex meteorological, hydrological and thermal processes that control snowmelt, and also the challenging access and data acquisition in the extreme alpine environments. Here we use field measurement and numerical modeling to simulate the energy balance and hydrological fluxes in a steep high elevation permafrost affected rock slope at Aiguille du Midi (3842 m a.s.l), in the Mont-Blanc massif. Our results provide new information about water balance at the surface of steep rock slopes. Model results suggest that only ~25 % of the snowfall accumulates in our study site, the remaining ~75 % are redistributed by wind and gravity. Snow accumulation depth is inversely correlated with surface slopes between 40° to 70°. Snowmelt occurs between spring and late summer and most of it does not reach the rock surface due to the formation of an impermeable ice layer at the base of the snowpack. The annual effective snowmelt, that is available for infiltration, is highly variable and ranges over a factor of six with values between 0.05–0.28 m in the years 1959–2021. The onset of the effective snowmelt occurs between May and August, and ends before October. It precedes the first rainfall by one month on average. Sublimation is the main process of snowpack mass loss in our study site. Model simulations at varying elevations show that effective snowmelt is the main source of water for infiltration above 3600 m a.s.l.; below, direct rainfall is the dominant source. The change from snowmelt-dominated to rainfall-dominated water availability is nonlinear and characterized by a rapid increase in water availability for infiltration. We suggest that this elevation of water availability transition is highly sensitive to climate change, if snowmelt-dominated permafrost-affected slopes experience an abrupt increase in water input that can initiate rock slope failure.

Published
2022
Full Text
View/download PDF

6. Temporal Consolidation Strategy for Ground-Based Image Displacement Time Series: Application to Glacier Monitoring

Author

A. Walpersdorf, Xavier Bodin, Emmanuel Malet, Emmanuel Trouvé, Blaise Girard, Flavien Vernier, Guilhem Marsy, William Castaings, Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance (LISTIC), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Tenevia, Institut des Sciences de la Terre (ISTerre), and Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA)

Subjects
Atmospheric Science, Series (mathematics), Consolidation (soil), QC801-809, Computer science, business.industry, Geophysics. Cosmic physics, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Inverse transform sampling, photogrammetry, Displacement (vector), Ocean engineering, [SDU]Sciences of the Universe [physics], Displacement measurement, time series analysis, glacier monitoring, Redundancy (engineering), Global Positioning System, [INFO]Computer Science [cs], Computers in Earth Sciences, Time series, Adaptive optics, business, TC1501-1800, Algorithm
Abstract

International audience; In this article, we present a method for combiningimage-based displacements to build time series. This method takesadvantage of the redundancy of these displacements, which comesfrom multiple possible combinations between images. The proposedmethod combines common master series with a differentmaster date to construct a single time series of relative displacements.We were able to test thismethod on displacements computedusing images from a stereo time-lapse device recording imagesof the Argentière glacier during the summer and fall of 2019.Our method was compared to two other displacement aggregationstrategies: a simple common master approach and the classicalinversion method. In order to perform this comparison, displacementdata from four permanent GPS are used. The results showthat our method provides a more accurate time series of relativedisplacements than those obtained with the other methods. Thehigher accuracy of the proposed method makes the detection ofseasonal variations in glacier velocity possible.

Published
2021
Full Text
View/download PDF

7. Climatic and structural controls on Late‐glacial and Holocene rockfall occurrence in high‐elevated rock walls of the Mont Blanc massif (Western Alps)

Author

Philip Deline, Christophe Ogier, Julien Carcaillet, Emmanuel Malet, Magali Rossi, David García-Sellés, Ludovic Ravanel, and Xavi Gallach

Subjects
geography, Rockfall, geography.geographical_feature_category, Geography, Planning and Development, Earth and Planetary Sciences (miscellaneous), Geochemistry, Glacial period, Mont blanc massif, Permafrost, Geology, Holocene, Earth-Surface Processes
Published
2020
Full Text
View/download PDF

8. Did the Younger Dryas to Holocene climate transition favour high seismicity rates in the north‐western Alps?

Author

Banjan, Mathilde, Christian, Crouzet, Pierre, Sabatier, Hervé, Jomard, Manon, Bajard, Francois, Demory, Anne‐Lise, Develle, Jean‐Philippe, Jenny, Bernard, Fanget, Emmanuel, Malet, Findling, Nathaniel, Philippe, Alain, Julien, Didier, Vincent, Bichet, Sylvain, Clapot, and Erwan, Messager

Subjects
YOUNGER Dryas, ROCKFALL, PLEISTOCENE-Holocene boundary, GLACIAL climates, GLACIAL lakes, LAKE sediments
Abstract

In the French north‐western Alps, several lakes of glacial origin, such as Aiguebelette and La Thuile, present some mass‐transport deposits within their sedimentary sequences. These event layers can result from lake sediment destabilization eventually triggered by earthquakes. On Lake Aiguebelette, based on sedimentological, geochemical and magnetic analyses, and high‐resolution seismic and bathymetric surveys a ca 1 m thick event layer was identified in the deepest lake basin and a synchronous ca 2 cm thick deposit in the shallow basin. Age‐depth models based on radiocarbon ages reveal that both mass‐transport deposits in Lake Aiguebelette occurred around the Younger Dryas – Early Holocene climatic transition (i.e. 11 700 cal bp) time range. In Lake La Thuile, located 30 km away, unique mass‐transport deposits (translational slide type) were recorded at the same time range in sedimentary records. Additionally, high‐resolution seismic profiles previously acquired in Lake Annecy and Lake Bourget support the hypothesis of significant mass‐transport deposits occurring at the Younger Dryas – Early Holocene time range. These outcomes on four north‐western peri‐Alpine and Alpine lakes highlight the regional occurrence of mass‐transport deposits in the Younger Dryas – Early Holocene time range. Seismic and rockfall events are discussed as potential sources of these significant and similarly aged mass‐transport deposits. Based on this study and a literature review, the authors suggest that mechanisms induced by rapid climate change and glacial retreat, such as crustal rebound and erosional unloading, could favour the triggering of earthquakes and rockfall events. In the case of mass‐transport deposits archived in north‐western Alpine lakes during this time period, this study favours the hypothesis of increased seismicity as the primary source driving process involved. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

10. Diffusion et dynamique de la culture du millet dans les Alpes ouest-européennes sur la base des concentrations en miliacine dans les sédiments lacustres

Author

Jacob, J., Anaëlle Simonneau, Manon Bajard, Erwan Messager, Yves Billaud, Claude Le Milbeau, Jérôme Poulenard, Charline Giguet-Covex, William Rapuc, Elise Doyen, Pierre Sabatier, David Etienne, Emmanuel Malet, Bernard Fanget, Fabien Arnaud, Emmanuel Chapron, Ulrich Von Grafenstein, Michel Magny, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Biogéosystèmes Continentaux - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Département des Recherches Archéologiques Subaquatiques et Sous-Marines [Marseille] (DRASSM), Ministère de la Culture (MC), Institut national de recherches archéologiques préventives (Inrap), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Géographie de l'environnement (GEODE), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Elisa Nicoud, Marie Balasse, Emmanuel Desclaux, Isabelle Théry-Parisot, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Université Toulouse - Jean Jaurès (UT2J)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Elisa Nicoud, Marie Balasse, Emmanuel Desclaux, Isabelle Théry-Parisot, Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and JACOB, Jérémy

Subjects
millet, [SDE.MCG]Environmental Sciences/Global Changes, lake sediments, sédiments lacustres, GEOF, [SDU] Sciences of the Universe [physics], [SDU.STU.CL] Sciences of the Universe [physics]/Earth Sciences/Climatology, bronze Age, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Age du Bronze, [SHS.ENVIR] Humanities and Social Sciences/Environmental studies, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.GC] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDV.EE.ECO] Life Sciences [q-bio]/Ecology, environment/Ecosystems, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, PANOPLY, agriculture, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Alps, diffusion, [CHIM.ORGA] Chemical Sciences/Organic chemistry, [SDE.ES]Environmental Sciences/Environmental and Society, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, [SDE.MCG] Environmental Sciences/Global Changes, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, [SDU.STU.ST] Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDE.ES] Environmental Sciences/Environmental and Society, Alpes
Abstract

Domestication and diffusion of cereals lead to major transformation in ancient civilizations. For broomcorn millet (Panicum miliaceum), initiatives from several research groups aim at precising the timing and pathways of its diffusion from its Asian cradle during the 6th millennium BC to Western Europe during the Bronze Age, mostly from charred seeds recovered in archaeological contexts. An alternative approach consists of detecting miliacin, a molecular biomarkers that is specific to millet in lake sediments. The first occurrence of miliacin in sediments attests to the beginning of millet cultivation in the catchment and the evolution of miliacin concentration helps unraveling the dynamics of millet cultivation and consumption. Here we provide a first regional synthesis of miliacin sedimentary records from six lakes in the European Western Alps (Ledro and Iseo; Italy, Le Bourget, La Thuile, Paladru and Aiguebelette; France). This allows us (1) providing additional milestones to the journey of millet diffusion in Europe; (3) identifying potential local differences in the dynamics of millet cultivation., La domestication et la diffusion des céréales furent deux étapes clé dans le développement des sociétés. Jusqu'à aujourd'hui, la diffusion du millet commun (Panicum miliaceum) depuis son foyer de domestication en Asie au 6ème millénaire av J.C. jusqu'en Europe de l'Ouest à l'âge du Bronze a été principalement étudiée par l'analyse de graines en contexte archéologique. Une approche alternative et complémentaire consiste à tracer la présence de la miliacine, biomarqueur moléculaire du millet, dans les sédiments lacustres afin non seulement de déterminer les dates de premières cultures et consommation dans le bassin versant des lacs, mais aussi d'évaluer les phases d'emprise et de déprise au moyen des variations de concentrations de miliacine dans les sédiments. Ici, nous proposons une première synthèse régionale des dates d'apparition de la miliacine et de l'évolution de ses concentrations dans les sédiments de six lacs des Alpes italiennes et françaises (lac de Ledro et lac d'Iseo en Italie et Le Bourget, La Thuile, Paladru et Aiguebelette en France). Cette synthèse nous permet de discuter le calendrier de diffusion du millet dans les Alpes au regard des travaux en contexte archéologique, et de cerner de potentielles hétérogénéités spatiales dans la dynamique de culture de cette céréale.

Published
2021

11. Lake Dziani Dzaha (Mayotte, Indian Ocean) : A modern analogue for type I kerogen formation

Author

Edouard Bard, Fabien Arnaud, I. Antheaume, F. Gelin, Manuela Capano, Vincent Grossi, Magali Ader, S. Mignard, F. Baudin, Didier Jézéquel, Pierre Cartigny, Laurent Simon, I. Jovovic, Emmanuel Malet, Pierre Adam, Collège de France - Chaire Evolution du climat et de l'océan, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), STMicroelectronics [Crolles] (ST-CROLLES), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Équipe 3 - Écologie, Évolution, Écosystemes Souterrains (E3S), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Total E&P, Centre scientifique et Technique Jean Feger (CSTJF), and TOTAL FINA ELF

Subjects
2HAL, δ18O, Aquatic ecosystem, Geochemistry, BARD Édouard, Anoxic waters, Diagenesis, Texte intégral (accès ouvert), chemistry.chemical_compound, web-evolution-climat-ocean, chemistry, Source rock, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Kerogen, Sedimentary rock, traité, Chaires, Green River Formation, Geology, Document sous DOI (Digital Object Identifier)
Abstract

https://hal.archives-ouvertes.fr/hal-03252301; International audience; Summary In the past, highly productive (hyper)saline and alkaline environments have proved propitious for large accumulation of sedimentary OM that led to the formation of Type I kerogens, such as those of the Green River Formation. A sediment core that covers most of the history of Lake Dziani Dzaha, a hypereutrophic saline, alkaline and mostly anoxic crater lakewhich waspostulatedto be a modern analogue of such environments, has been investigated using several analytical approaches comprising bulk (Rock-Eval and C, N, S elemental analyses), isotopic (δ13,14C, δ15N, δ18O, δ33,34,36S), and sedimentological descriptions. This study revealed that, despite strong environmental changes undergone by the lake since its formation, the conditions prevailing in the lake supported by a continuous high primary production have led to an excellent preservation of OM and to early diagenetic reductive and sulfurization processes which have yielded an exceptionally reduced character of the OM with respect to its short diagenetic history (< 6 ky). The similarities observed between the sediments of Lake Dziani Dzaha and some source rocks associated to Type I kerogens suggest that early diagenetic processes can have a strong and rapid impact on the accumulation of OM in some (semi)closed and highly productive aquatic ecosystems.

Published
2021
Full Text
View/download PDF

12. The role of early diagenesis in the shaping of geochemical records : an example from Lake Dziani Dzaha, Mayotte

Author

Emmanuel Malet, François Baudin, Vincent Grossi, Pierre Cartigny, Ingrid Antheaume, Francois Gelin, Laurent Simon, Manuela Capano, Salomé Mignard, Magali Ader, Fabien Arnaud, Edouard Bard, Pierre Adam, Ivan Jovovic, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre scientifique et Technique Jean Feger (CSTJF), and TOTAL FINA ELF

Subjects
web-evolution-climat-ocean, 2HAL, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Geochemistry, traité, Chaires, BARD Édouard, Geology, Document sous DOI (Digital Object Identifier), Diagenesis, Texte intégral (accès ouvert)
Abstract

https://hal.archives-ouvertes.fr/hal-03252301; International audience

Published
2021
Full Text
View/download PDF

13. Climate change and human lakeside adaptation in the Central Afar Region (Lake Abhe basin, Ethiopia & Djibouti) during the Later Stone Age - Neolithic transition: a multi-scalar and multi-proxy approach

Author

Gourguen Davtian, Marie Revel, Lamya Khalidi, Isabelle Crevecoeur, Laurent Bruxelles, Thibault Colombier, Carlo Mologni, Laure Schenini, Fabien Arnaud, Eric Chaumillon, Clément Ménard, Jessie Cauliez, Emmanuel Malet, Travaux et recherches archéologiques sur les cultures, les espaces et les sociétés (TRACES), Ministère de la Culture et de la Communication (MCC)-École des hautes études en sciences sociales (EHESS)-Université Toulouse - Jean Jaurès (UT2J)-Centre National de la Recherche Scientifique (CNRS), Culture et Environnements, Préhistoire, Antiquité, Moyen-Age (CEPAM), Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), École des hautes études en sciences sociales (EHESS)-Université Toulouse - Jean Jaurès (UT2J)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), De la Préhistoire à l'Actuel : Culture, Environnement et Anthropologie (PACEA), and Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)

Subjects
2. Zero hunger, Geography, Later Stone Age, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, 13. Climate action, Scalar (mathematics), Climate change, Physical geography, 15. Life on land, Adaptation, Structural basin, Multi proxy, ComputingMilieux_MISCELLANEOUS
Abstract

Throughout the last 20 ka, tropical Africa was the site of significant hydrological changes related to variations in the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that gradual long-term monsoon humid oscillations (African Humid Period ~14 – ~6 ka) were punctuated by centennial-scale episodes of hyperaridity (HS1, YD, 8.2 ka, 4.2 ka). These abrupt hydrological changes could have caused drastic transformations in landscape patterns, providing favourable ecosystems, but also produced arid environments that may have restricted human exploitation of the landscape.The Abhe Lake basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater and terrigenous inputs from the Ethiopian Highlands, and is a hydro-sedimentary system sensitive to hydroclimatic change. Since 2014, in the context of the VAPOR-Afar and PSPCA programs (in Ethiopia and Djibouti respectively), we have intensified scientific investigations over this basin with the objective of exploring the evolution of Holocene hydroclimatic change, its impact on landscapes and on prehistoric human behaviour during one of the most forcible transitions in human history, that from a dominantly hunter-gathering way of life to the food production societies one.We present the first results of this research that combines paleoclimatological, geomorphological and geoarchaeological studies based on a new set of 14C datations on two lacustrine cores, on several morpho-sedimentary outcrops and on 8 new archaeological sites spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the modalities of the African Humid Period and of the 8.2 and 4.2 ka hyperarid episodes, coupling paleolake-level reconstitution and lacustrine sediment analysis (paleolimnology, geochemistry); b) evaluate the impact of these hydroclimatic oscillations on perilacustrine sedimentary formation processes, especially for pedogenic formations; c) and better understand the relationship between environmental change and the development of one of the most important economic and cultural innovations, that of domestication.

Published
2021
Full Text
View/download PDF

14. Rockfall and vulnerability of mountaineers on the west face of the Aiguille du Goûter (classic route up Mont Blanc, France), an interdisciplinary study

Author

Guilhem Marsy, Marco Marcer, Ludovic Ravanel, Jacques Mourey, P.A Duvillard, Emmanuel Malet, and Pascal G. Lacroix

Subjects
geography, Rockfall, geography.geographical_feature_category, Mountaineering, Snowmelt, Vulnerability, Climate change, Physical geography, Couloir, Training (civil), Tourism
Abstract

In high alpine environments, climate change leads to an increase in rockfall destabilizations. They represent a threat for sports and tourism activities in high mountain and especially for mountaineering. This danger of rockfall is particularly important on the classic route up Mont Blanc (4,809 m a.s.l., Mont Blanc massif, France), on the west face of the Aiguille du Goûter (3,863 m a.s.l.), and is responsible for at least 29 % of the accidents that occur in this sector. Despite the intensity of the geomorphological processes at work and the vulnerability of climbers, few scientific studies have been carried out on the occurrence of rockfalls and their triggering factors in the Goûter area. Based on a multi-method monitoring system (5 seismic sensors, an automatic digital camera, 3 subsurface temperature sensors, a pyroelectric sensor, a high-resolution topographical survey, 2 weather stations and a rain gauge) the objective of our study is therefore to quantitatively document the occurrence of rockfalls and their triggering factors in the Grand Couloir du Goûter in order to better assess the vulnerability of mountaineers in this sector. Our results show that in the high-Alpine and permafrost-affected Aiguille du Goûter west face, rockfalls are mostly frequent during the snowmelt period which favors the action of thermo-mechanical processes linked to the infiltration of liquid water into the cracks of the rock. During periods when the couloir is completely clear of snow, rockfalls are 2.5 times less frequent, and the thermo-mechanical processes involved in the rockfall triggering are limited by the absence of moisture in the ground. These results also show that climbers' awareness of the risk of rockfalls remains limited. What’s more, they do not adapt – or only slightly – their behavior to this risk, despite a particularly high accident rate. Important work on prevention and dissemination of the knowledge here acquired (newsletters, training for professionals and amateurs, awareness campaigns) among mountaineers is therefore still really necessary.

Published
2021
Full Text
View/download PDF

15. Paravani, a puzzling lake in the South Caucasus

Author

Ulrich von Grafenstein, Jérôme Poulenard, Charline Giguet-Covex, Pierre Sabatier, Anne-Lise Develle, David Lordkipanidze, Erwan Messager, Emmanuel Malet, Jean-Pascal Dumoulin, Soumaya Belmecheri, Sébastien Nomade, Vincent Scao, Arnaud Mazuy, Fabien Arnaud, Ana Mgeladze, Mathilde Banjan, Estelle Herrscher, Bruno Wilhelm, Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes (UGA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Georgian National Museum, Laboratoire méditerranéen de préhistoire Europe-Afrique (LAMPEA), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC), Culture et Environnements, Préhistoire, Antiquité, Moyen-Age (CEPAM), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire de mesure du carbone 14 (LMC14 - UMS 2572), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Tree-Ring Research, University of Arizona, ANR-12 JSH3-003-01, ANR-12-JSH3-0003,ORIMIL,La culture du millet dans le Caucase pré- et proto-historique : Origine et développement(2012), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)

Subjects
South caucasus, 010506 paleontology, Holocene, Sediment, Vegetation, 15. Life on land, 010502 geochemistry & geophysics, medicine.disease_cause, 01 natural sciences, Natural (archaeology), Lake, Vegetation history, Erosion, Pollen, [SDE]Environmental Sciences, medicine, Tree cover, Physical geography, Environmental history, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

International audience; Sediments of Lake Paravani, the largest natural lake in the South Caucasus, were analysed to reconstruct the millennial history of the environment. Pollen analysis, previously undertaken on the first core retrieved in the middle of the lake, revealed a vegetation history for the last 12 millennia. As part of the present study, a new core was taken from the northwestern part of the lake. Pollen analysis was performed on this new core with the same methodology as for the previous one. A sedimentological and geochemical analysis was also conducted on both cores in order to gain an understanding of the dynamics of erosion in the catchment area in response to landscape modifications. The results show that the sediment deposits within Lake Paravani yield rather complex and puzzle-like palaeoecological records. Despite the differences between the two records, correlations have been made that are supported by the 14C dates. By combining all of the data from both cores, it was finally possible to reconstruct the puzzle of the environmental history recounted by the Lake Paravani sediments. This reconstructed history is composed of four main phases: 1. A steppic environment marked by pronounced erosion processes from 12 000 to 10 000 cal. BP; 2. A transition phase characterized by the expansion of grasses (Poaceae) from 10 000 to 9-8 000 cal. BP; 3. A more forested phase from 9-8 000 to 2 000 cal. BP, during which the erosion fluxes decreased; and 4. A decline in tree cover probably due to human activities over the last 2 millennia.

Published
2021
Full Text
View/download PDF

16. Permafrost in monitored unstable rock slopes in Norway – New insights from rock wall temperature monitoring, geophysical surveying and numerical modelling

Author

Michael Krautblatter, Johannes Leinauer, Emmanuel Malet, Bernd Etzelmüller, Benjamin Jacobs, Harald Øverli Eriksen, P.A Duvillard, Ingrid Skrede, Ludo Ravanel, Gudrun Dreiås Majala, Martina Böhme, Andreas Aspaas, Lene Kristensen, Florence Magnin, Christin Hilbich, Christian Hauck, R. L. Hermanns, Sebastian Westermann, and Justyna Czekirda

Subjects
Temperature monitoring, geography, geography.geographical_feature_category, Plateau, Seasonality, medicine.disease, Fault scarp, Permafrost, Spring (hydrology), medicine, Geological survey, Electrical resistivity tomography, Geomorphology, Geology
Abstract

The warming and subsequent degradation of mountain permafrost within alpine areas is an important process influencing the stability of steep slopes and rock faces. The unstable and monitored slopes of Mannen (Møre and Romsdal, southern Norway) and Gámanjunni-3 (Troms and Finnmark, northern Norway) were classified as high-risk sites by the Norwegian Geological Survey (NGU). Failure initiation has been suggested to be linked to permafrost degradation, but the detailed permafrost distribution at the sites is unknown. Rockwall (RW) temperature loggers at both sites have measured the thermal regime since 2015, showing mean rock surface temperatures between +2.5 °C and −1.6 °C depending on site and aspect. Between 2016 and 2019 we conducted 2D and 3D electrical resistivity tomography (ERT) surveys on the plateau and directly within the rock wall back scarp of the unstable slopes at both sites. In combination with geophysical laboratory analysis of rock wall samples from both sites, the ERT soundings indicate wide-spread permafrost areas, especially at Gámanjunni-3. Finally, we conducted 2D thermal modelling to evaluate the potential thermal regime. Rockwall temperatures, together with ERT measurements and modelling of the ground thermal regime strongly indicate, at least locally, the presence of permafrost. Displacement rates show a seasonality, with higher velocities during spring and early summer than the rest of the year, possibly related to snow melting.

Published
2021

17. Hydro-climatic fluctuations and their impact on Lake Abhe environments (Ethiopia & Djibouti): a lesson from the past 10,000 years

Author

Gourguen Davtian, Lamya Khalidi, Eric Chaumillon, Carlo Mologni, Fabien Arnaud, Laurent Bruxelles, Anne-Lise Develle, Marie Revel, Jessie Cauliez, Mathieu Schuster, Pierre Sabatier, and Emmanuel Malet

Subjects
2. Zero hunger, 13. Climate action, 15. Life on land, 6. Clean water
Abstract

Throughout the last 14 ka, tropical Africa experienced significant hydrological changes that were mainly driven by the orbital precession cycle, which controls the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that long-term monsoon humid oscillations (African Humid Period / AHP ~14 – ~6 ka) were punctuated by centennial-scale episodes of hyperaridity. However, the abrupt or gradual aridification modalities since the end of the AHP and the modalities of the centennial-scale episodes, as well as their impacts on past and current environments are still debated.The Lake Abhe basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater originating in the Ethiopian Highlands, and represents a hydro-sedimentary system sensitive to hydro-climatic changes in East Africa. Today it is characterized by residual lakes (Gamari and Afambo lakes) and a hyper-arid climate, while during the AHP, the Abhe basin was occupied by a Mega-lake and by humid environmental conditions. Holocene climatic disruptions drastically changed the landscapes and ways of life along this basin. The aim of this study is to describe, interpret and estimate the impact of hydro-climatic oscillations on the evolution of Lake Abhe’s littoral lacustrine environments and palaeolandscapes since the AHP from different viewpoints.Indeed, this research combines paleoclimatological and geomorphological studies based on a new set of 14C ages on two lacustrine cores and on several morpho-sedimentary outcrops spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the hydrological modalities of the AHP including short-term arid episodes linked to Younger Dryas and 8.2 ka North Atlantic events; b) recognise some paleo-shoreline geomorphic features linked to lake level fluctuations, as well as the development littoral pedological horizons and the activation/shutdown of the perilacustrine fluvial network during humid and arid events; c) track these changes until the present day, and discuss their evolution scenario in the near future.Comparing with other regional climatic records, we show how Lake Abhe basin was highly reactive to East African monsoonal regimes, and how current hydrological changes could impact its environments.

Published
2021
Full Text
View/download PDF

18. Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years

Author

Mathilde Zebracki, Pascale Louvat, Emmanuel Malet, Pierre Lefebvre, Didier Jézéquel, Pierre Le Pape, Alkiviadis Gourgiotis, John R. Bargar, Pascale Blanchart, Nicolas Menguy, Jean-Louis Reyss, Guillaume Morin, Pauline Merrot, Camille Baya, Charlotte Cazala, Pierre Sabatier, Jérôme Gaillardet, Arnaud Mangeret, Olivier Diez, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PSE-ENV/SEDRE/LELI, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), PSE-ENV/SEDRE/USDR, Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Minéralogie Environnementale (MinEnv), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), United States Department of Energy (DOE)DE-AC02-76SF00515IPGP multidisciplinary program PARIParis-IdF Region SESAME Grant12015908IRSNLS 20942, ANR-18-IDEX-0001,Université de Paris,Université de Paris(2018), Service des déchets radioactifs et des transferts dans la géosphère (IRSN/PSE-ENV/SEDRE), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Propriétés des amorphes, liquides et minéraux [IMPMC] (IMPMC_PALM), Laboratoire de recherche sur le devenir des pollutions de sites radioactifs (IRSN/PSE-ENV/SEDRE/LELI), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Unité d'expertise des sites et des déchets radioactifs (IRSN/PSE-ENV/SEDRE/USDR), and IMPMC_Minéralogie Environnementale (IMPMC_MINENV)

Subjects
media_common.quotation_subject, lake sediments, chemistry.chemical_element, 010501 environmental sciences, 010502 geochemistry & geophysics, 01 natural sciences, uranium, Coffinite, Organic matter, 0105 earth and related environmental sciences, media_common, chemistry.chemical_classification, Multidisciplinary, Isotopes of uranium, Lability, Authigenic, Uranium, diagenetic aging, noncrystalline species, Diagenesis, Speciation, chemistry, 13. Climate action, Environmental chemistry, Physical Sciences, [SDE]Environmental Sciences, uranium isotopes
Abstract

The long-term fate of uranium-contaminated sediments, especially downstream former mining areas, is a widespread environmental challenge. Essential for their management is the proper understanding of uranium (U) immobilization mechanisms in reducing environments. In particular, the long-term behavior of noncrystalline U(IV) species and their possible evolution to more stable phases in subsurface conditions is poorly documented, which limits our ability to predict U long-term geochemical reactivity. Here, we report direct evidence for the evolution of U speciation over 3,300 y in naturally highly U-enriched sediments (350–760 µg ⋅ g(−1) U) from Lake Nègre (Mercantour Massif, Mediterranean Alps, France) by combining U isotopic data (δ(238)U and ((234)U/(238)U)) with U L(3)-edge X-ray absorption fine structure spectroscopy. Constant isotopic ratios over the entire sediment core indicate stable U sources and accumulation modes, allowing for determination of the impact of aging on U speciation. We demonstrate that, after sediment deposition, mononuclear U(IV) species associated with organic matter transformed into authigenic polymeric U(IV)–silica species that might have partially converted to a nanocrystalline coffinite (U(IV)SiO(4)·nH(2)O)-like phase. This diagenetic transformation occurred in less than 700 y and is consistent with the high silica availability of sediments in which diatoms are abundant. It also yields consistency with laboratory studies that proposed the formation of colloidal polynuclear U(IV)–silica species, as precursors for coffinite formation. However, the incomplete transformation observed here only slightly reduces the potential lability of U, which could have important implications to evaluate the long-term management of U-contaminated sediments and, by extension, of U-bearing wastes in silica-rich subsurface environments.

Published
2021
Full Text
View/download PDF

19. Induced Polarization of Carbonates

Author

Emmanuel Malet, Myriam Schmutz, Adrian Cerepi, Bruno Garcia, R. Garcia-Artigas, P.A Duvillard, Stéphane Jaillet, P. Vaudelet, André Revil, Ravi Sharma, NS Panwar, Indian Institute of Technology Roorkee (IIT Roorkee), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Indian Institute of Technology Delhi (IIT Delhi), Institut Polytechnique de Bordeaux (Bordeaux INP), IFP Energies nouvelles (IFPEN), and Universitat de Barcelona (UB)

Subjects
Materials science, 010504 meteorology & atmospheric sciences, Condensed matter physics, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Hydrogeophysics, 010502 geochemistry & geophysics, 01 natural sciences, Induced polarization, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Electrical resistivity and conductivity, Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences
Abstract

International audience; Complex conductivity measurements of carbonate rocks are scarce despite the occurrence of these rocks at the surface of the Earth. The complex conductivity spectra of 57 carbonate samples were measured in a broad frequency range and at four salinities (NaCl). A simple model of induced polarization is developed to be applied to induced polarization measurements in the field. The in-phase conductivity (related to conduction) is reported as a function of the pore water conductivity to determine the (intrinsic) formation factor and the surface conductivity. The surface conductivity and the normalized chargeability are linearly correlated to the specific surface area divided by the tortuosity of the pore space. This observation is consistent with a dynamic Stern layer polarization model, the Stern layer being the inner layer of the electrical double layer coating the grains. The quadrature conductivity is observed to be proportional to the measured normalized chargeability in agreement with the prediction of the constant phase model. The effect of the texture is discussed and we observe a power-law relationship between the permeability and the formation factor. Then, we illustrate how this model can be applied to field data performed over a carbonate syncline in the French Alps. A 1.9 km long profile is used to separate the glacial till infilling the depression from the underlying limestones in terms of induced polarization properties. The induced polarization survey allows imaging the water content and the specific surface area of the formations down to a depth of 220 m.

Published
2021
Full Text
View/download PDF

20. Evolution of noncrystalline uranium in lake sediments over 3,300 years

Author

Mathilde Zebracki, Emmanuel Malet, Jean-Louis Reyss, Didier Jézéquel, Charlotte Cazala, Nicolas Menguy, Alkiviadis Gourgiotis, Pauline Merrot, John R. Bargar, Pierre Le Pape, Guillaume Morin, Pierre Lefebvre, Pascale Louvat, Pascale Blanchart, Pierre Sabatier, Camille Baya, Jérôme Gaillardet, Arnaud Mangeret, and Olivier Diez

Subjects
chemistry, Geochemistry, chemistry.chemical_element, Uranium, Geology
Published
2021
Full Text
View/download PDF

21. Pluri-millenial evolution of uranium speciation in lacustrine sediments

Author

Pierre Sabatier, Emmanuel Malet, Arnaud Mangeret, Didier Jézéquel, Olivier Diez, Mathilde Zebracki, Pascale Louvat, Pierre Le Pape, Pierre Lefebvre, Jérôme Gaillardet, Charlotte Cazala, Pauline Merrot, Guillaume Morin, Alkiviadis Gourgiotis, Jean-Louis Reyss, Camille Baya, John R. Bargar, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PSE-ENV/SEDRE/LELI, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Minéralogie Environnementale (MinEnv), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and ATHENA, Irsn

Subjects
[SDE] Environmental Sciences, Radionuclide, Environmental remediation, media_common.quotation_subject, Sediment, chemistry.chemical_element, Uranium, Anoxic waters, Deposition (geology), Diagenesis, Speciation, chemistry, Environmental chemistry, [SDE]Environmental Sciences, Environmental science, media_common
Abstract

Uranium (U) is a toxic radionuclide which environmental dissemination must be limited. In this regard, understanding U immobilization mechanisms in reducing environments is essential for improving the management of radioactive waste and the remediation of contaminated sites. In particular, determining the long-term behavior of non-crystalline U(IV) species in (sub-)surface conditions is of growing importance, as these environmentally-relevant species have been recently showed to play a major role in U mobility. For this purpose, we investigated the evolution of U speciation over a pluri-millennial period in naturally U-enriched sediments from Lake Nègre (alt. 2354 m, Mercantour, France) as an analogue of contaminated systems. Several sediment cores were sampled at 24 m of water depth and preserved under anoxic conditions. Bottom sediments were dated back to 8700 cal BP. These organic- and Si-rich sediments display increasing U concentration with depth, from 350 to more than 1000 µg/g. Sequential ultrafiltration of surface waters and uranium isotopic ratios (238U/235U and (234U/238U)) of sediments and waters suggest that the deposition mode of U did not vary significantly with time, thus giving the opportunity to follow the effect of diagenesis on U speciation over more than 1000 years. Uranium LIII-edge X-Ray Absorption Near-Edge Structure (XANES) analysis shows that U is rapidly reduced in the upper sediment layers and is fully reduced at depth. Preliminary Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy data at the U LIII-edge reveals that U speciation evolved with depth in the sediment core, suggesting an effect of diagenesis in anoxic conditions on U solid speciation. Our results may help to design long-term storage conditions that are able to enhance the formation of poorly soluble U species in U-contaminated soils and sediments.

Published
2020

22. Etablishing the first continuous Holocene tephrostratigraphy on Kerguelen Archipelago, subantarctic Indian Oean

Author

Eivind Støren, Stéphane Guédron, Bertrand Moine, Anouk Leloup, Nathalie Vanderputten, Jérôme Poulenard, Anne-Lise Develle, Elisabeth Michel, Pierre Sabatier, Emmanuel Malet, Fabien Arnaud, Nicolas Le Viavan, Bernard Fanget, Jacques-Louis de Beaulieu, Jean-Louis Reyss, Marc De Batist, Vincent Perrot, Jostein Bakke, Katrien Heirman, Aymerick Servettaz, Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Department of Earth Science and Bjerknes Centre for Climate Research, University of Bergen, Allégaten 41, 5007 Bergen, Norway, L'Institut polaire français Paul-Emile Victor (IPEV), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Universiteit Gent = Ghent University (UGENT), Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Renard Centre of Marine Geology, Department of Geology and Soil Sciences, Ghent University, Krijgslaan 281 S8, B-9000 Ghent, Belgium

Subjects
geography, Paleontology, geography.geographical_feature_category, Volcano, Outcrop, [SDE]Environmental Sciences, Archipelago, Sediment, Glacial period, Chronostratigraphy, Geology, Holocene, Chronology
Abstract

Here we present the first Holocene-long continuous chronology of volcanic eruptions on Kerguelen archipelago, where no evidence of Holocene volcanic activity has been published so far. Our chronicle is based upon sedimentological, chronological and geochemical data form two sediment cores, taken in two different depocenters of a large lake, Lake Armor, located ca. 70 km away from the archipelago’s potentially active volcanic area. This allowed us to confidently attribute the origin of pumice-rich or ash-rich layers to contemporaneous volcanic eruptions. Altogther eight main eruptions, as well as three secondary ones, were here documented and dated, among which the youngest occurred during the Middle Age, between 890 and 980 AD. The oldest eruption is also by far the strongest one and deposited more than 1.2m of up-to 3cm large pumices, 70 km away from the volcanic edifice. It occurred at the very beginnning of the Holocene (11 ka cal. BP), suggesting a climatic control after glacial retreat upon volcanic activity. Additionnal evidences from lake sediment and geological outcrops, both close to Lake Armor and in remote areas over Kerguelen mainland, open the future possibility of a better reconstruction of major eruptions deposit spreading and thus an assessment of their intensity. This established chronostratigraphy will be useful to synchronise paleoenvironment record at least at the scale of the archipelago as well as in surrounding marine areas where Holocene climate reconstructions are particularly sparse.

Published
2020
Full Text
View/download PDF

23. Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842ma.s.l., Mont Blanc massif)

Author

Sebastian Westermann, Emmanuel Malet, Paolo Pogliotti, Florence Magnin, Ludovic Ravanel, Philip Deline, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), ARPA Valle d'Aosta (Aosta Valley Regional Environmental Protection Agency), Aosta Valley Regional Environmental Protection Agency (ARPA), International Permafrost Association, and EDYTEM, Océane Giorda

Subjects
[SDE] Environmental Sciences, 010504 meteorology & atmospheric sciences, Snow field, 010502 geochemistry & geophysics, Permafrost, 01 natural sciences, Rockfall, Snow, Snow line, Geomorphology, 0105 earth and related environmental sciences, Earth-Surface Processes, Rock wall permafrost, geography, geography.geographical_feature_category, Bedrock, Firn, Bedrock temperature monitoring, Energy balance modelling, Active layer, 13. Climate action, [SDE]Environmental Sciences, human activities, Geology
Abstract

International audience; Since the early 2000s, a remarkable amount of rockfalls has been observed in permafrost areas of the mid-latitude mountain ranges concurrently to hot summers. This study explores the seasonal thaw (ST) in permafrost rock walls of the Aiguille du Midi site (3842 m a.s.l., Mont Blanc massif). We first analyse six years of temperature records in three 10 m-deep boreholes against air temperature (AT) and a four-year time series of pictures showing the snow conditions on two rock faces. Then, we test the sensitivity of the active layer against eight snow fall scenarios using the 1-D surface energy balance and heat conduction model CryoGrid 3 forced by in-situ measurements from a vertical face. Snow falls occur all the year round at this elevation and play an important role for the active layer thickness (ALT), but the snow cover and its control are highly heterogeneous. A long-lasting of a snow cover during spring/early summer delays the ST and reduces the ALT. The thicker and the more spatially-continuous is the snow cover, the stronger are the delay and ALT reduction. Convective clouds could also reinforce this pattern. The summer AT and heat waves are the dominant controlling factors of the ALT. But summer snow falls can sometimes persist for several days on the rock surface and reduce the effect of the heat waves. Active layer can thicken during the early fall, except if the snow starts to accumulate on the rock surface and favours the refreezing. The timing of the snow fall is the most critical parameter to determine the snow effect on the ALT. This study suggests that the characteristics of the bedrock and snow accumulation (steepness, surface roughness, and sun-exposure) must be taken into account to better understand the formation and changes of the active layer and its possible implications for rockfall triggering.

Published
2017
Full Text
View/download PDF

24. Past African dust inputs in Western Mediterranean area controlled by the complex interaction between ITCZ, NAO and TSI

Author

Boris Vannière, Marie Nicolle, Maxime Debret, Yoann Copard, Pierre Sabatier, Marie-Charlotte Bellingery, Charlotte Skonieczny, Jérôme Poulenard, Julien Didier, Emmanuel Malet, Anne-Lise Develle, Jean-Louis Reyss, Yves Perrette, Christophe Colin, Didier Swingedouw, Christine Piot, Benjamin Chazeau, Fabien Arnaud, Isabelle Jouffroy-Bapicot, Maëlle Kelner, and Maxime Leblanc

Subjects
Centennial, Terrigenous sediment, Climatology, Intertropical Convergence Zone, Climate system, Mediterranean area, Environmental science, Atmospheric dust, Mineral dust, Solar irradiance
Abstract

North Africa is the largest source of mineral dust on Earth, which has multiple impacts on the climate system; however, our understanding of decadal to centennial changes in African dust emissions over the last few millennia is limited. Here, we present a high-resolution multiproxy analysis of sediment core from high-elevation lake Bastani, in Corsica Island to reconstruct past African dust inputs to the Western Mediterranean area over the last 3150 yrs cal BP. Clay Mineralogy and geochemical data allows us to identify that terrigenous fluxes are almost exclusively related to atmospheric dust deposition from the West and North Sahara over this period, which is consistent with current observations. High resolution geochemical contents provide a reliable proxy of Saharan dust inputs with millennial to centennial scale variations. Millennial variations have been correlated to the long term southward migration of the Intertropical Convergence Zone (ITCZ) with an increase of dust input since 1070 yrs cal BP. This correlation suggests a strong link with ITCZ and could reflect the increased availability of dust sources to be mobilized with an increase in wind and a decrease in precipitation over West and North Africa. For centennial to decadal variations, wavelet analyses show that since 1070 yr cal BP, NAO is the main climatic forcing with an increase of Saharan dust input during positive phase, as suggested by previous study over the last decades. However, when ITCZ is in a northern position, before 1070 yr cal BP, wavelet analyses indicate that total solar irradiance (TSI) is the main forcing factor, with an increase of African dust input during low TSI. With climate reanalysis over the instrumental era, during low TSI we observe a significant negative anomaly in pressure over Africa which is known to increase the dust transport. These two climatic forcing factors (NAO, TSI) modulate Saharan dust inputs to the Mediterranean area at centennial timescale through changes in wind and transport pathways.

Published
2019

25. Supplementary material to 'Past African dust inputs in Western Mediterranean area controlled by the complex interaction between ITCZ, NAO and TSI'

Author

Pierre Sabatier, Marie Nicolle, Christine Piot, Christophe Colin, Maxime Debret, Didier Swingedouw, Yves Perrette, Marie-Charlotte Bellingery, Benjamin Chazeau, Anne-Lise Develle, Maxime Leblanc, Charlotte Skonieczny, Yoann Copard, Jean-Louis Reyss, Emmanuel Malet, Isabelle Jouffroy-Bapicot, Maëlle Kelner, Jérôme Poulenard, Julien Didier, Fabien Arnaud, and Boris Vannière

Published
2019
Full Text
View/download PDF

26. Projet VAPOR-Afar, Volcanological & Archaeological Program for Obsidian Research – Afar, Ethiopia

Author

Lamya Khalidi, Carlo Mologni, Clément Ménard, Marzia Gabriele, Gourguen Davtian, Hala Alarashi, Arnaud, F., Berhane, H., Laurent Bruxelles, Félicien Capellari, Jessie Cauliez, Coulombier, T., Chaumillon, E., Lorène Chesnaux, Cécile Doubre, Blade Engda Redae, Eugenie Gauvrit Roux, Bernard Gratuze, Hainsworth, E., Joséphine Lesur, Emmanuel Malet, Ahmad Mahammad, Clive Oppenheimer, Marie Revel, Aurélie Salavert, Mathieu Schuster, Chantal Tribolo, Vidal, C., Antoine Zazzo, Culture et Environnements, Préhistoire, Antiquité, Moyen-Age (CEPAM), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Travaux et recherches archéologiques sur les cultures, les espaces et les sociétés (TRACES), École des hautes études en sciences sociales (EHESS)-Université Toulouse - Jean Jaurès (UT2J)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), ARCHEORIENT - Environnements et sociétés de l'Orient ancien (Archéorient), Université Lumière - Lyon 2 (UL2)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherches archéologiques préventives (Inrap), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les Archéomatériaux (IRAMAT), Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS), Archéozoologie et histoire des sociétés (AHS), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Department of Geography [Cambridge, UK], University of Cambridge [UK] (CAM), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Archéozoologie, archéobotanique : sociétés, pratiques et environnements (AASPE), IRAMAT-Centre de recherche en physique appliquée à l’archéologie (IRAMAT-CRP2A), Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne-Centre National de la Recherche Scientifique (CNRS), Cauliez J., Bon F., Bruxelles L., Crevecoeur I., Khalidi L., Lesur J., Pleurdeau D., Tribolo C., Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), IRAMAT - Centre Ernest Babelon (IRAMAT-CEB), Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Montaigne-Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Montaigne-Université de Technologie de Belfort-Montbeliard (UTBM), Archéozoologie, histoire des sociétés et des peuplements animaux (AHS), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)

Subjects
[SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

27. Du blanc au-dessus du vide. Monitoring multi-paramètres de la formation et de l’évolution d’un pont de neige au-dessus d’une crevasse sur un glacier alpin

Author

Ludovic Ravanel, Emmanuel Malet, and Philippe Batoux

Subjects
glacier, crevasse, snow bridge, instrumentation, mountaineering, high mountain, alpinisme, haute montagne, pont de neige, General Medicine
Abstract

On glaciers, snow bridges that form above crevasses allow mountaineers and skiers to cross them easily, but their break represents a high risk of potentially fatal falls for practitioners. To understand the formation and evolution of these fragile structures, we sat up instrumentation at 3450 m a. s. l. in the Mont Blanc massif. The device, whose installation required complex logistics, surveys the main meteorological parameters several times a day. Moreover, the geometry of the snow bridge is surveyed by an automatic camera while an extensometer measures the evolution of the opening of the crevasse. Although the ensemble is well suited to the conditions of the high mountain environment, its maintenance is delicate due to the strong instability of the environment (movements of the glacier, extreme weather conditions) while processes unexpected as important (wind filling of the crevasse) are challenging a part of the planned instrumentation (e. g. automatic photo inside the crevasse)., Sur les glaciers, les ponts de neige qui se forment au-dessus des crevasses permettent aux alpinistes et aux skieurs de les traverser facilement mais leur rupture éventuelle fait supporter un risque élevé de chute potentiellement mortelle aux pratiquants. Pour comprendre la formation et l’évolution de ces structures fragiles, une instrumentation a été mise en place à 3450 m d’altitude dans le massif du Mont Blanc. Le dispositif, dont l’installation a requis une logistique complexe, relève plusieurs fois par jour les principaux paramètres nivo-météorologiques. Par ailleurs, un appareil photo automatique suit la géométrie du pont de neige tandis qu’un extensomètre mesure l’évolution de l’ouverture de la crevasse. Si l’ensemble apparait bien adapté aux conditions de la haute montagne, sa maintenance est toutefois rendue délicate par la forte instabilité du milieu (mouvements du glacier, conditions météorologiques extrêmes) tandis que des processus non pressentis comme importants (remplissage éolien de la crevasse) remettent en question une partie de l’instrumentation prévue (photo automatique à l’intérieure de la crevasse)., Ravanel Ludovic, Malet Emmanuel, Batoux Philippe. Du blanc au-dessus du vide. Monitoring multi-paramètres de la formation et de l’évolution d’un pont de neige au-dessus d’une crevasse sur un glacier alpin. In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 69-75.

Published
2017
Full Text
View/download PDF

28. Ruissellement et dissolution d’un bassin versant lapiazé des karsts de Patagonie, île Tarlton, archipel de Madre de Dios (Chili)

Author

Florian Chenu, Georges Marbach, Emmanuel Malet, Fabien Hoblea, Laurent Morel, Expéditions Ultima Patagonia, Richard Maire, Bernard Tourte, Denis Morales, and Stéphane Jaillet

Subjects
dissolution, karren, karst, Patagonia, runoff, instrumentation, General Medicine, ruissellement, lapié, Patagonie
Abstract

Karsts of Patagonia (Madre de Dios archipelago, Chile, 50° S) are among the more wettest in the world (> 8 000 mm. year-1). The rate of surface dissolution on bare karst is estimated at more than 100 mm/ millennium from glacial erratics, exhumed dykes or historical paintings. We have instrumented an experimental watershed on karren and recorded meteorological parameters (precipitation, temperature, wind speed, direction) and parameters of runoff into karren (discharge, conductivity, temperature) used to understand the flow on limestone in subpolar oceanic setting. The wind, spray and especially the rainfalls explain the dissolution of the limestone surface. A topographic survey shows the drainage stairs organization whose genesis and evolution seem to be conditioned by running «step pool system » resulting in high variability of flows during the flood event., Les karsts de Patagonie (archipel de Madre de Dios, Chili, 50° S) comptent parmi les plus arrosés de la planète (> 8 000 mm/ an). À partir de socles d’erratiques glaciaires, de dykes exhumés ou de peintures historiques, les taux de dissolution superficielle sur karst nu sont estimés supérieurs à 100 mm/ millénaire. Nous avons instrumenté un bassin-versant sur lapiés nu ; le suivi de paramètres météorologiques (précipitation, température, vitesse et direction du vent) et de paramètres de ruissellement dans les rigoles (débit, conductivité, température) permet d’affiner la connaissance de l’écoulement sur calcaire en contexte océanique subpolaire. Le vent, les embruns et surtout le régime des précipitations contrôlent les modalités de la dissolution des calcaires en surface. Un relevé topographique fin permet de montrer une organisation du drainage en marches d’escalier dont la genèse et l’évolution semblent conditionner un fonctionnement en « step-pool system » se traduisant notamment par une forte variabilité des débits durant l’onde de crue., Jaillet Stéphane, Morel Laurent, Maire Richard, Malet Emmanuel, Marbach Georges, Morales Denis, Chenu Florian, Hobléa Fabien, Tourte Bernard, Expéditions Ultima Patagonia. Ruissellement et dissolution d’un bassin versant lapiazé des karsts de Patagonie, île Tarlton, archipel de Madre de Dios (Chili). In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 137-146.

Published
2017
Full Text
View/download PDF

29. Pastoralism increased vulnerability of a subalpine catchment to flood hazard through changing soil properties

Author

Delphine Rioux, Pierre Sabatier, Yann Bertrand, Jérôme Poulenard, Claire Blanchet, Gentile Francesco Ficetola, Emmanuel Malet, Wentao Chen, Erwan Messager, Manon Bajard, Anne-Lise Develle, Ludovic Gielly, Fabien Arnaud, Charline Giguet-Covex, and Christian Crouzet

Subjects
010506 paleontology, Flood myth, Paleontology, Sediment, Weathering, 15. Life on land, Sedimentation, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Podzol, humanities, Pedogenesis, 13. Climate action, parasitic diseases, Erosion, Physical geography, Loss on ignition, Ecology, Evolution, Behavior and Systematics, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Soil erosion is strongly linked to both precipitation patterns and land-use. We examine the effects of erosion and its drivers (i.e. human or/and climate) on soil evolution from the study of lacustrine archives in the northern French Alps. Multi-proxy analyses of the Lake Gers sediment sequence combined with the study of soils and rocks of its catchment allowed to reconstruct its evolution over the past 4.6 kyr. This included 14C dating, short-lived radionuclides, geochemistry, loss on ignition, grain-size analyses, as well as plant and mammal DNA analyses. A total of 127 instantaneous deposits were identified among the continuous sedimentation in the lake and 93 were interpreted as flood deposits. Erosion was quantified for the whole catchment considering both the continuous sedimentation and the flood deposit thicknesses. The catchment is mainly formed by andesitic sandstones over which Andosols and Podzols can develop. However, low weathered materials from colluviation constitute the main input to the lake. Four main phases of changes in soil weathering were recorded by increases in K2O/TiO2 ratios, associated with an increase in both erosion and flood-frequency. Two phases were associated with climate cooling in the Western Alps, from 2.65 to 2.5 and from 1.45 to 1.3 cal kyr BP. The two others (1.9–1.75 and 0.9–0.4 cal kyr BP) were triggered with deforestation, with cow grazing during the Roman period, and with grazing of cows, sheep and goats during the Medieval period, amplified by the onset of the Little Ice Age. The increase in erosion and flood frequency after 950 cal yr BP indicates substantial damages to soils of the catchment including increase of their erodibility over the last millennia.

Published
2019

30. Sediment DNA helps revealing ecosystem collapse and recovery post-alien invasion on pristine Kerguelen Islands

Author

Gentile Francesco Ficetola, Jérôme Poulenard, Pierre Sabatier, Erwan Messager, Ludovic Gielly, Anouk Leloup, Etienne, D., Bakke, J., Emmanuel Malet, Bernard Fanget, Storen, B., Jean Louis Reyss, Taberlet, J. L., Fabien Arnaud, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), and Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

31. DNA from lake sediments reveals long-term ecosystem changes after a biological invasion

Author

Jostein Bakke, Gentile Francesco Ficetola, Jérôme Poulenard, Anouk Leloup, Emmanuel Malet, Pierre Taberlet, Pierre Sabatier, Ludovic Gielly, Fabien Arnaud, Eivind Støren, Bernard Fanget, David Etienne, Jean-Louis Reyss, Erwan Messager, Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Culture et Environnements, Préhistoire, Antiquité, Moyen-Age (CEPAM), Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Océan et Interfaces (OCEANIS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ESKER project IPEV, the French Polar Institute 1094-PALAS, Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 0301 basic medicine, Geologic Sediments, Climate Change, [SDE.MCG]Environmental Sciences/Global Changes, Environmental Studies, Biodiversity, Introduced species, Biology, 010603 evolutionary biology, 01 natural sciences, Invasive species, 03 medical and health sciences, C2FN, Abundance (ecology), Animals, Ecosystem, Environmental DNA, 14. Life underwater, Coprophilous fungi, Applied Ecology, Research Articles, Mammals, Multidisciplinary, Ecology, [SDE.IE]Environmental Sciences/Environmental Engineering, SciAdv r-articles, Plant community, DNA, [SHS.GEO]Humanities and Social Sciences/Geography, Plants, 15. Life on land, biology.organism_classification, [SDE.ES]Environmental Sciences/Environmental and Society, Lakes, 030104 developmental biology, 13. Climate action, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Introduced Species, Research Article
Abstract

Rabbits have had a stronger impact on the landscape and plant communities of a remote island than one century of climate change., What are the long-term consequences of invasive species? After invasion, how long do ecosystems require to reach a new equilibrium? Answering these questions requires long-term, high-resolution data that are vanishingly rare. We combined the analysis of environmental DNA extracted from a lake sediment core, coprophilous fungi, and sedimentological analyses to reconstruct 600 years of ecosystem dynamics on a sub-Antarctic island and to identify the impact of invasive rabbits. Plant communities remained stable from AD 1400 until the 1940s, when the DNA of invasive rabbits was detected in sediments. Rabbit detection corresponded to abrupt changes of plant communities, with a continuous decline of a dominant plant species. Furthermore, erosion rate abruptly increased with rabbit abundance. Rabbit impacts were very fast and were stronger than the effects of climate change during the 20th century. Lake sediments can allow an integrated temporal analysis of ecosystems, revealing the impact of invasive species over time and improving our understanding of underlying mechanisms.

Published
2018
Full Text
View/download PDF

32. Corrigendum to '6-kyr record of flood frequency and intensity in the western Mediterranean Alps - Interplay of solar and temperature forcing' [Quaternary Science Reviews 170 (2017) 121–135]

Author

Emmanuel Malet, Jean-Louis Reyss, Pierre Taberlet, Yves Perrette, Ludovic Gielly, Bruno Wilhelm, Anne-Lise Develle, Adeline Bichet, Fanny Moiroux, Fabien Arnaud, Wentao Chen, Jérôme Poulenard, Manon Bajard, Gentile Francesco Ficetola, Cécile Pignol, Pierre Sabatier, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Laboratoire de génétique et biologie cellulaire (LGBC), Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Mediterranean climate, 010506 paleontology, Archeology, Global and Planetary Change, 010504 meteorology & atmospheric sciences, Flood frequency analysis, [SDE.IE]Environmental Sciences/Environmental Engineering, [SDE.MCG]Environmental Sciences/Global Changes, Quaternary science, Geology, Forcing (mathematics), [SHS.GEO]Humanities and Social Sciences/Geography, 01 natural sciences, [SDE.ES]Environmental Sciences/Environmental and Society, C2FN, 13. Climate action, Climatology, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Ecology, Evolution, Behavior and Systematics, Intensity (heat transfer), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2018
Full Text
View/download PDF

33. Determination of warm, sensitive permafrost areas in near-vertical rockwalls and evaluation of distributed models by electrical resistivity tomography

Author

Alexandre R. Bevington, Emmanuel Malet, Ludovic Ravanel, Michael Krautblatter, Philip Deline, and Florence Magnin

Subjects
geography, geography.geographical_feature_category, Distributed element model, Snow, Mont blanc massif, Permafrost, Geophysics, Rockfall, 13. Climate action, Fracture (geology), Electrical resistivity tomography, Glacial period, Geomorphology, Geology, Earth-Surface Processes
Abstract

Alpine rockwalls with warm permafrost (near 0°C) are the most active rockfall detachment zones in the Mont Blanc massif (MBM, French Alps) with more than 380 recent events. Near-vertical rockwall permafrost is spatially controlled by variations in rock fractures, snow cover, and microtopography. A reliable method to validate the distribution of permafrost in critical and unstable areas does not yet exist. We present seven electrical resistivity tomography (ERT) surveys measured on five near-vertical rockwalls in the MBM from 2012 and 2013 that have been calibrated with measurements on a granite sample in the laboratory. ERT shows consistent measurements of remaining sensitive permafrost relating to inferred temperatures from 0 to −1.5°C. ERT results demonstrate evidence of topographic controls on permafrost distribution and resistivity gradients that appear to reflect crest width. ERT results are compared to two permafrost index maps that use topoclimatic factors and combine effects of thin snow and fractures, where index model spatial resolution is crucial for the validation with ERT. In cryospheric environments, index maps seem to overestimate permafrost conditions in glacial environments. As a consequence, the sensitive areas of permafrost may slightly deviate from the results from distributed models that are only constrained by topoclimatic factors and interpreted with consideration of local fracture and snow conditions. This study demonstrates (i) that the sensitive and hazardous areas of permafrost in near-vertical rock faces can be assessed and monitored by the means of temperature-calibrated ERT and (ii) that ERT can be used for distributed model validation.

Published
2015
Full Text
View/download PDF

34. Monitoring d'un lac de haute altitude. Le cas du lac de la Muzelle (massif des Ecrins)

Author

Laurent Fouinat, Emmanuel Malet, Pierre Sabatier, Jérôme Poulenard, Richard Bonet, Clotilde Sagot, Fabien Arnaud, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Parc national des Ecrins, Emmanuel Malet, Laurent Astrade, and Referent HAL Edytem, Christine Maury

Subjects
[SDE] Environmental Sciences, [SDE]Environmental Sciences
Published
2017

35. Instrumentation hydrométéorologique spatialisée sur le bassin versant du Vorz (massif de Belledonne)

Author

Georges-Marie Saulnier, Thierry Barth, Emmanuel Malet, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Emmanuel Malet, Laurent Astrade, and Referent HAL Edytem, Christine Maury

Subjects
hydrology, snow cover, image analysis, monitoring, meteorology, [SDE] Environmental Sciences, 13. Climate action, [SDE]Environmental Sciences, Forestry, hydrologie, météorologie, instrumentation, analyse d'image, enneigement, General Medicine, 6. Clean water, Geology, Snow cover
Abstract

The Vorz catchment in Belledonne massif is impacted by important flash flood, as for example the flashflood event of August 2005. These floods show the need to better understand this catchment and the hydrometeorological processes. Thus, a monitoring program take place on this mountain catchment of 18km ² (elevation ranges between 950 to 2 977m) and with significant nival melting contribution. The monitoring protocol is based on the bet that it is possible to monitor several hydrometeorological variables such as temperatures, rainfall, orographic and thermal gradient with a spatial distributed network of sensors at limited costs. This network allowed to collect most essential data between 2009 and 2011 that can be used to supply and force different models of snow and hydrology. The results of these models enable the study of flood (flash flood and melting flood) but also water resource management in the context of climate change., Le bassin versant du Vorz, dans le massif de Belledonne, a connu de crues conséquentes, notamment en août 2005. Ces crues ont mis en évidence la nécessité de mieux comprendre ce bassin et son fonctionnement hydrométéorologique. Ainsi, un programme d’instrumentation a été mis en place sur ce bassin de montagne d’une surface de 18 km ² (entre 760 et 2 977 m) et présentant des caractéristiques nivales marquées. Le protocole avait pour objectif d’étudier la faisabilité d’une instrumentation spatialisée à coût raisonné des différentes variables hydrométéorologiques indispensables pour bien modéliser le cycle de l’eau, c’est-à-dire les températures, précipitations, ensoleillement, gradients orographiques et thermiques ou encore l’évolution de l’enneigement. Ce réseau, installé entre 2009 et 2011, a montré qu’il permettait de recueillir l’essentiel des données nécessaires à alimenter et contraindre les modèles d’enneigement et de fonte liés aux modèles hydrologiques, permettant l’étude et la prévision des crues (fonte et orage), ainsi que les gestions des ressources en eau et la conciliation des usages, en particulier dans l’optique des évolutions climatiques actuelles., Barth Thierry, Malet Emmanuel, Saulnier Georges-Marie. Instrumentation hydrométéorologique spatialisée sur le bassin versant du Vorz (massif de Belledonne). In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 111-120.

Published
2017

36. Instrumentation thermique et cinématique des parois à permafrost du massif du Mont Blanc

Author

Ludovic Ravanel, Jan Beutel, Paolo Pogliotti, P.A Duvillard, Umberto Morra di Cella, Fabrizio Troilo, Stephan Gruber, Grégoire Guillet, Florence Magnin, Emmanuel Malet, Philip Deline, EDYTEM, Océane Giorda, Emmanuel Malet, Laurent Astrade, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Fondation Montagne Sure, ARPA Valle d'Aosta (Aosta Valley Regional Environmental Protection Agency), Aosta Valley Regional Environmental Protection Agency (ARPA), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Glaciology, Geomorphodynamics and Geochronology, Department of Geography [Zürich], and Universität Zürich [Zürich] = University of Zurich (UZH)-Universität Zürich [Zürich] = University of Zurich (UZH)

Subjects
Mont Blanc massif, rock walls, permafrost, temperature measurements, extensometry, high mountain, [SDE] Environmental Sciences, 010504 meteorology & atmospheric sciences, 13. Climate action, [SDE]Environmental Sciences, 0211 other engineering and technologies, 02 engineering and technology, General Medicine, 01 natural sciences, massif du Mont Blanc, thermométrie, fissurométrie, haute montagne, parois rocheuses, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences
Abstract

Unlike the superficial deposits in which the presence of permafrost is indicated by geomorphological evidences, its occurrence in the rock walls can only be suggested by the existence of perennial ice sheets or hanging glaciers. Everywhere else, only indirect (geophysics) or direct temperature measurements make it possible to verify its presence. In these rock walls, permafrost and its degradation due to global warming are at the origin of rock falls and rock avalanches with a devastating power. In order to know the state and the thermal evolution of the rock walls, to parameterize or validate the permafrost distribution models, or to survey the kinematics of the fractures in the bedrock, it is necessary to monitor these rock walls. This article presents the methods of instrumentation and the equipment used for more than 10 years in the Mont Blanc massif as well as the associated research questions., Contrairement aux formations superficielles au sein desquelles la présence de permafrost peut être attestée par certains indices géomorphologiques, son occurrence dans les parois rocheuses ne peut qu’être suggérée par l’existence de couvertures de glace pérennes ou de glaciers suspendus. Partout ailleurs, seules des mesures indirectes (géophysiques) ou directes de température permettent de vérifier sa présence. Dans ces parois, le permafrost et sa dégradation causée par le réchauffement climatique sont à l’origine d’écroulements et d’avalanches rocheuses aux effets dévastateurs. Pour connaître l’état et l’évolution thermique des parois, paramétrer ou valider les modèles de distribution du permafrost, ou suivre la cinématique des fractures qui découpent les massifs rocheux, il est donc nécessaire d’instrumenter les parois. Cet article présente les modalités d’instrumentation et les matériels utilisés depuis plus de 10 ans dans le massif du Mont Blanc ainsi que les questions de recherche qui leur sont associées., Ravanel Ludovic, Malet Emmanuel, Duvillard Pierre-Alain, Magnin Florence, Deline Philip, Guillet Grégoire, Troilo Fabrizio, Pogliotti Paolo, Morra di Cella Umberto, Beutel Jan, Gruber Stephan. Instrumentation thermique et cinématique des parois à permafrost du massif du Mont Blanc. In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 27-38.

Published
2017

37. Monitoring des régimes thermiques des sols en montagne. Expériences alpines actuelles

Author

Jérôme Poulenard, Philippe Choler, Emmanuel Malet, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Emmanuel Malet, and Laurent Astrade

Subjects
[SDE]Environmental Sciences
Published
2017

38. Dynamique géomorphologique des torrents. Interets de l'emploi des appareil photographiques automatiques

Author

Guillaume Piton, Johan Berthet, Coraline Bel, Firmin Fontaine, Hervé Bellot, Emmanuel Malet, Laurent Astrade, Frédéric Liébault, Alain Recking, Marie Juppet, Kristian Royer, Université Grenoble Alpes, IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Office National des Forêts (ONF), Emmanuel Malet, Laurent Astrade, and Referent HAL Edytem, Christine Maury

Subjects
[SDE] Environmental Sciences, [SDE]Environmental Sciences
Published
2017

39. L'apport d'appareils photo reflex autonomes pour le suivi quasi-continu de la dynamique des glaciers rocheux. Exemple dans les Alpes et dans les Andes

Author

Xavier Bodin, Emmanuel Malet, Flavien Vernier, Guilhem Marsy, Héla Hadhri, Dario Trombotto, Referent HAL Edytem, Christine Maury, Emmanuel Malet, Laurent Astrade, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance (LISTIC), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])

Subjects
[SDE] Environmental Sciences, photogrammétrie time-lapse rock glacier kinematics, [SDE]Environmental Sciences, suivi des déplacements de surface, surface displacement monitoring, glacier rocheux, permafrost, time-lapse photogrammetry
Abstract

Enchassés au creux de nombreux hauts vallons de montagne, les glaciers rocheux sont des formes indicatrices de la présence d'un permafrost riche en glace se déformant de façon lente et continue le long des versants. Les déplacements de surface sont en général mesurés par la répétition de levés de blocs marqués par GPS différentiel, avec une précision élevée (de l'ordre du cm) sur une sélection de quelques dizaines de point, et à un pas de temps annuel ou de quelques mois, ou par photogrammétrie aérienne, permettant alors une couverture spatiale complète de la forme selon une discrétisation (taille de pixel) dépendante du système optique utilisé, mais avec une répétition qui n'est souvent au mieux que de plusieurs années. Les vitesses d'écoulement des glaciers rocheux sont typiquement de l'ordre du mètre par an, mais de fortes fluctuations sont observées, à la fois dans le temps et dans l'espace. Afin d'apporter des éléments de compréhension nouveaux sur la variabilité spatiale et temporelle de la cinématique de surface des glaciers rocheux, nous avons développé un système de suivi (dimension temporelle) optique à haute résolution (dimension spatiale) par photogrammétrie time-lapse. Le dispositif a été installé sur deux sites, l'un dans les Andes d'Argentine (suivi par système monoscopique : avec un seul appareil photo), et l'autre dans les Alpes françaises (suivi stéréoscopique : avec deux appareils photo). Nous présentons ici une synthèse descriptive des installations ainsi qu'une analyse préliminaire de l'apport de ce système pour l'étude de mouvements lents.

Published
2017

40. Reconstitution de l’évolution du paysage du lac de La Thuile (Massif des Bauges, Savoie) durant l’Holocène. Mise en évidence d’une domination des processus érosifs liés à l’homme à l’étage montagnard

Author

Daniel Arnaud, Laurent Augustin, Jean-Louis Reyss, Bernard Fanget, Jérôme Poulenard, Fernand David, Anne-Lise Develle, Pierre Sabatier, Manon Bajard, Emmanuel Malet, Fabien Arnaud, and Christian Crouzet

Subjects
activités humaines, climat, végétation, apports terrigènes, sols, sédiments lacustres, terrigenous inputs, lake sediments, soils, vegetation, climate, human activities, Forestry, General Medicine, Geology
Abstract

Lake La Thuile, in the Northern French Prealps (874 m a. s. l.), provides an 18 m long sedimentary sequence spanning the entire Lateglacial/ Holocene period. The high resolution multi-proxy (sedimentological, palynological, geochemical) analysis of the uppermost 6.2 meters reveals the Holocene dynamics of erosion in the catchment in response to landscape modifications. The mountain belt led us to take an interest in this altitude, which is favorable to human activities and is sufficiently disconnected from large valleys to capture a specific sedimentary signal. From 12 to 4.5 ka cal. BP, the onset of hardwood species triggered a drop in erosion following the Late glacial/ Holocene transition. The forest became denser and favored slope stabilization while erosion processes were very weak. Soils were acidifying. A first erosive phase was initiated at ca. 4.5 ka cal. BP without evidence of human presence in the catchment. Then, the forest declined at approximately 3000 cal. BP, suggesting the first human influence on the landscape. Two erosive phases are related to anthropic activities : approximately 2500 cal. BP during the Roman period, and at 1600 cal. BP in the Middle Ages. In contrast, the lower erosion produced during the Little Ice Age suggests that anthropic activities dominated the erosive processes and completely masked the natural effects of climate on erosion., Le lac de La Thuile dans les préalpes du nord (874 m) fournit une séquence sédimentaire de 18 m de long. L’analyse multi-proxies haute résolution des 6,2 premiers mètres de sédiment incluant des données sédimentaires, palynologiques et géochimiques, associées à une chronologie bien établie, documente l’évolution holocène de l’érosion dans le bassin versant et les modifications du paysage. Le bassin versant est suffisamment déconnecté des grandes plaines pour capturer un signal sédimentaire spécifique à ce milieu. De 12 à 4,5 ka cal. BP, la végétation se développe avec l’apparition de feuillus alors que l’érosion diminue à la suite de la transition Tardiglaciaire-Holocène. La forêt devient plus dense, stabilise les pentes et empêche l’érosion des sols qui se développent en s’acidifiant. Une première phase érosive est initiée vers 4,5 ka cal. BP. Le paysage change avec le développement de la hêtraie-sapinière. Les taxons anthropiques font leur apparition autour de 3 000 cal. BP. Deux autres phases érosives sont à mettre en relation avec l’ouverture du milieu par les activités humaines : à partir de 2,5 ka cal. BP, à la fin de l’âge du Bronze et pendant la période Romaine, et après 1,6 ka cal. BP avec le Moyen-âge. Elles engendrent un rajeunissement et une recarbonatation des sols. L’érosion plus faible produite durant le Petit âge Glaciaire suggère que les activités anthropiques dominent les processus liés à l’érosion et masquent complètement l’impact du climat sur l’érosion à cette altitude., Bajard Manon, Sabatier Pierre, David Fernand, Develle Anne-Lise, Reyss Jean-Louis, Fanget Bernard, Malet Emmanuel, Arnaud Daniel, Augustin Laurent, Crouzet Christian, Poulenard Jerôme, Arnaud Fabien. Reconstitution de l’évolution du paysage du lac de La Thuile (Massif des Bauges, Savoie) durant l’Holocène. Mise en évidence d’une domination des processus érosifs liés à l’homme à l’étage montagnard. In: Collection EDYTEM. Cahiers de géographie, numéro 18, 2015. Sols et matières organiques. Mémoires et héritages. pp. 41-56.

Published
2015
Full Text
View/download PDF

41. Timescale-dependent interplays of solar and temperature forcing to explain 6kyrs of flood frequency and intensity in the western Mediterranean Alps

Author

Pierre Sabatier, Bruno Wilhelm, Francesco Ficetola Gentile, Moiroux, G. F., Jérôme Poulenard, Anne-Lise Develle, Bichet, A., Wentao Chen, cecile Pignol, Jean Louis Reyss, Ludovic Gielly, Manon Bajard, Yves Perrette, Emmanuel Malet, Pierre Taberlet, Fabien Arnaud, Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Océan et Interfaces (OCEANIS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), EDYTEM, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, [SDE]Environmental Sciences, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDE.ES]Environmental Sciences/Environmental and Society, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

42. 6-kyr record of flood frequency and intensity in the western Mediterranean Alps – Interplay of solar and temperature forcing

Author

Jérôme Poulenard, Ludovic Gielly, Fabien Arnaud, Gentile Francesco Ficetola, Emmanuel Malet, Yves Perrette, Fanny Moiroux, Pierre Taberlet, Bruno Wilhelm, Cécile Pignol, Wentao Chen, Jean-Louis Reyss, Anne-Lise Develle, Pierre Sabatier, Manon Bajard, Adeline Bichet, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Laboratoire de génétique et biologie cellulaire (LGBC), Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Océan et Interfaces (OCEANIS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Mediterranean climate, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Flood frequency and intensity, Human activity, [SDE.MCG]Environmental Sciences/Global Changes, Mesoscale meteorology, Forcing (mathematics), 01 natural sciences, C2FN, Paleoclimatology, Earthquakes, Precipitation, Sedimentology, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, Global and Planetary Change, Flood myth, Ancient DNA, [SDE.IE]Environmental Sciences/Environmental Engineering, Geology, [SHS.GEO]Humanities and Social Sciences/Geography, Western mediterranean alps, Lake sediment, [SDE.ES]Environmental Sciences/Environmental and Society, 13. Climate action, Climatology, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; The high-resolution sedimentological and geochemical analysis of a sediment sequence from Lake Savine(Western Mediterranean Alps, France) led to the identification of 220 event layers for the last 6000 years.200 were triggered by flood events and 20 by underwater mass movements possibly related to earthquakesthat occurred in 5 clusters of increase seismicity. Because human activity could influence theflood chronicle, the presence of pastures was reconstructed through ancient DNA, which suggested thatthe flood chronicle was mainly driven by hydroclimate variability. Weather reanalysis of historical floodsallow to identify that mesoscale precipitation events called “East Return” events were the main triggersof floods recorded in Lake Savine. The first part of this palaeoflood record (6e4 kyr BP) was characterizedby increases in flood frequency and intensity in phase with Northern Alpine palaeoflood records. Bycontrast, the second part of the record (i.e., since 4 kyr BP) was phased with Southern Alpine palaeofloodrecords. These results suggest a palaeohydrological transition at approximately 4 kyr BP, as has beenpreviously described for the Mediterranean region. This may have resulted in a change of flood-pronehydro-meteorological processes, i.e., in the balance between occurrence and intensity of local convectiveclimatic phenomena and their influence on Mediterranean mesoscale precipitation events in thispart of the Alps. At a centennial timescale, increases in flood frequency and intensity corresponded toperiods of solar minima, affecting climate through atmospheric changes in the Euro-Atlantic sector

Published
2017
Full Text
View/download PDF

43. Late Holocene glacier activity on the Kerguelen Island, South Indian Ocean - reconstructed from distal glacier-fed lake sediments

Author

Bakke, J., Eivind Støren, Fabien Arnaud, Jérôme Poulenard, Emmanuel Malet, Pierre Sabatier, University of Bergen (UiB), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDE.IE]Environmental Sciences/Environmental Engineering, [SDE.MCG]Environmental Sciences/Global Changes, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDE.ES]Environmental Sciences/Environmental and Society, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

44. L'objet emblématique Lacs de Montagne. L'étude des sédiments lacustres au laboratoire EDYTEM

Author

Bruno Wilhelm, Maxime Debret, Laurent Millet, Cécile Pignol, Sidonie Révillon, Pierre Sabatier, Marc Desmet, Bernard Fanget, Fabien Arnaud, Charline Giguet-Covex, Emmanuel Malet, Dirk Enters, Jean-Philippe Jenny, and Jérôme Poulenard

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, General Medicine, 01 natural sciences, Geology, 0105 earth and related environmental sciences
Abstract

Arnaud Fabien, Giguet-Covex Charline, Wilhelm Bruno, Jenny Jean-Philippe, Sabatier Pierre, Poulenard Jerôme, Desmet Marc, Enters Dirk, Revillon Sidonie, Millet Laurent, Debret Maxime, Pignol Cécile, Malet Emmanuel, Fanget Bernard. L'objet emblématique Lacs de Montagne. L'étude des sédiments lacustres au laboratoire EDYTEM. In: Collection EDYTEM. Cahiers de géographie, numéro 16, 2014. Environnements, dynamiques et territoires de la montagne : Dix ans de recherches au laboratoire EDYTEM. pp. 107-118.

Published
2014
Full Text
View/download PDF

45. Seasonal changes of organic matter quality and quantity at the outlet of a forested karst system (La Roche Saint Alban, French Alps)

Author

Jérôme Poulenard, Fabien Hoblea, Marc Dzikowski, Yves Perrette, Emmanuel Malet, Bernard Fanget, Grégory Tissier, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Aquifer, 010501 environmental sciences, 01 natural sciences, Hydrology (agriculture), Cross-correlogram, Organic carbon flow, Organic matter, Karst spring, 0105 earth and related environmental sciences, Water Science and Technology, chemistry.chemical_classification, Hydrology, Total organic carbon, geography, geography.geographical_feature_category, Karst, [SDE.ES]Environmental Sciences/Environmental and Society, 6. Clean water, Fluorescent organic matter, chemistry, 13. Climate action, Environmental science, Water quality, Groundwater
Abstract

International audience; Because of its impact on water quality, organic matter (OM) in karst groundwater has been widely studied. The present article describes a method for monitoring OM in karst aquifers characterized by quick responses to rainfall. This method combines weekly manual sampling and continuous monitoring to provide, qualitative and quantitative information about OM flow. Weekly samples were analyzed for Total Organic Carbon (TOC) content and spectrofluorescence, while continuous monitoring was carried out at the main spring, using a field fluorimeter (310/400-700 nm and 280/300-600 nm) to quantify chromophoric organic matter (COM). The type and quantity of COM were defined by decomposing Excitation Emission Matrices (EEMs) and by applying a 2D fluorescence decomposition method. Continuous monitoring data showed that the dominant COM was humic-like (HL). We found three types of relationship between HL and discharge and between HL and TOC, showing that caution must be exercised when using field fluorimeter measurements to quantify TOC. Each relationship was characterized by global differences in OM content and by the presence of different percentages of non-chromophoric organic matter. These three relationships are associated with changes in hydrology and microorganism activity during the year. We used these relationships to estimate the annual OM flow (about 15 kg/ha/year) and thereby quantify OM flow during the year. Our results show the importance of the non-chromophoric organic matter in such estimation. That work illustrates the need to couple qualitative and quantitative monitoring of OM in karst spring to improve the global comprehension of karst system and of the sources implies in the OM flow.

Published
2013
Full Text
View/download PDF

46. Palaeoflood activity and climate change over the last 1400 years recorded by lake sediments in the north-west European Alps

Author

Pierre Sabatier, Bernard Fanget, Edouard Bard, Jean-Jacques Delannoy, Cécile Pignol, Bruno Wilhelm, Emmanuel Chapron, Olivier Magand, Thierry Courp, Fabien Arnaud, Kazuyo Tachikawa, Emmanuel Malet, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Chaire Evolution du climat et de l'océan, Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Evolution du climat et de l'océan, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Climate change, flood frequency, 01 natural sciences, Proxy (climate), flood intensit y, Arts and Humanities (miscellaneous), Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Flood myth, Global warming, Paleontology, Sediment, Glacier, 15. Life on land, Turbidite, climate change, lake sediment, last millennium, 13. Climate action, Climatology, Sedimentary rock, Geology
Abstract

International audience; A high-resolution sedimentological and geochemical study of a high-altitude proglacial lake (Lake Blanc, Aiguilles Rouges, 2352m a.s.l.) revealed 195 turbidites, 190 of which are related to flood events over the last 1400 years. We used the coarsest sediment fraction of each turbidite as a proxy for the intensity of each flood event. Because most flood events at this locality are triggered by localized summer convective precipitation events, the reconstructed sedimentary record reveals changes in the frequency and intensity of such events over the last millennium. Comparisons with other temperature, palaeohydrological and glacier reconstructions in the region suggest that the most intense events occurred during the warmest periods, i.e. during the Medieval Climate Anomaly (AD 800-1300) and the current period of global warming. On a multi-decadal time scale, almost all the flood frequency peaks seem to correspond to warmer periods, whereas multi-centennial variations in flood frequency appear to follow the regional precipitation pattern. Consequently, this new Alpine flood record provides further evidence of a link between climate warming and an increase in the frequency and intensity of flooding on a multidecadal time scale, whereas the centennial variability in flood frequencies is related to regional precipitation patterns.

Published
2013
Full Text
View/download PDF

47. Monitoring d’un lac de haute altitude. Le cas du lac de la Muzelle (massif des Écrins)

Author

Emmanuel Malet, Clotilde Sagot, Richard Bonet, Laurent Fouinat, Fabien Arnaud, Pierre Sabatier, and Jérôme Poulenard

Subjects
automatic monitoring, high altitude lake, multiparameter probe, sediment trap, Forestry, General Medicine, Geology, lac d'altitude, sonde multi-paramètres, trappe à sédiments, mesure automatique
Abstract

Since June 2012, Lake Muzelle’s monitoring is valuable for natural area managers, by establishing the lake’s ecological state, as well as research teams trying to better understand its current behavior. Instrumentation highlights the identification of seasonal and annual variability of physical and chemical properties as well as sedimentary income of the lacustrine system. The hourly sampling resolution allows precise monitoring of annual variability of the water mixing, of biological activity and major sedimentary inputs in relation with extreme flood events., Depuis juin 2012, la mise en place d’un suivi instrumental du lac de la Muzelle permet aux gestionnaires des espaces protégés de mieux déterminer l’état écologique du plan d’eau, mais aussi aux équipes de recherche de mieux comprendre son fonctionnement actuel. Ce dispositif a pour objectif de mettre en évidence la variabilité saisonnière et interannuelle du fonctionnement physico-chimique mais également sédimentaire du système lacustre. Grâce à ces enregistrements en continu, à une résolution horaire, nous pouvons estimer la variabilité des périodes de brassages annuels de la colonne d’eau, des périodes d’activité biologique et d’apports sédimentaires majeurs liés aux événements extrêmes de crues., Fouinat Laurent, Malet Emmanuel, Sabatier Pierre, Poulenard Jerôme, Bonet Richard, Sagot Clotilde, Arnaud Fabien. Monitoring d’un lac de haute altitude. Le cas du lac de la Muzelle (massif des Écrins). In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 191-198.

Published
2017

48. One thousand seven hundred years of interaction between glacial activity and flood frequency in proglacial Lake Muzelle (western French Alps)

Author

Emmanuel Malet, Laurent Fouinat, Anne-Lise Develle, Fabien Arnaud, Christian Crouzet, Clotilde Sagot, Jérôme Poulenard, Pierre Sabatier, Richard Bonet, David Etienne, Jean-Louis Reyss, Elise Doyen, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Centre National de la Recherche Scientifique (CNRS), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut national de recherches archéologiques préventives (Inrap), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Océan et Interfaces (OCEANIS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Parc national des Ecrins, Ecrins National Park, Communaute des Communes de l'Oisans, Association Nationale de la Recherche et de la Technologie, Deux Alpes Loisirs, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)

Subjects
lac, 010506 paleontology, Watershed, 010504 meteorology & atmospheric sciences, Flood frequency analysis, [SDV]Life Sciences [q-bio], 01 natural sciences, C2FN, flooding, Arts and Humanities (miscellaneous), open water, parasitic diseases, Organic matter, Glacial period, inondation, Loss on ignition, Little ice age, French Alps, alpes françaises, 0105 earth and related environmental sciences, Earth-Surface Processes, chemistry.chemical_classification, Hydrology, geography, geography.geographical_feature_category, Flood myth, sédiment lacustre, fluctuation, fungi, Glacier, flood reconstruction, foyer glaciaire, humanities, glacier fluctuation, lake sediment, chemistry, 13. Climate action, [SDE]Environmental Sciences, General Earth and Planetary Sciences, population characteristics, Geology, geographic locations
Abstract

Local glacial fluctuations and flood occurrences were investigated in the sediment sequence of proglacial Lake Muzelle. Based on geochemical analysis and organic matter content established using loss on ignition and reflectance spectroscopy, we identified six periods of increased glacial activity over the last 1700 yr. Each is in accordance with records from reference glaciers in the Alps. A total of 255 graded layers were identified and interpreted as flood deposits. Most of these occurred during glacial advances such as the Little Ice Age period and exhibit thicker deposits characterized by an increase in the fine grain-size fraction. Fine sediment produced by glacial activity is transported to the proglacial lake during heavy rainfall events. The excess of glacial flour during these periods seems to increase the watershed’s tendency to produce flood deposits in the lake sediment, suggesting a strong influence of the glacier on flood reconstruction records. Thus, both flood frequency and intensity, which is estimated based on layer thickness as a proxy, cannot be used in reconstruction of past extreme events because of their variability. There is a need to take into account changes in sediment supply in proglacial areas that could preclude satisfactory interpretation of floods in terms of past climate variability.

Published
2017
Full Text
View/download PDF

49. The overlooked human influence in historic and prehistoric floods in the European Alps

Author

Frédéric Guiter, Cécile Miramont, Rosine Cartier, Emmanuel Malet, Pierre Sabatier, Edward J. Anthony, Tiané Troussier, Elodie Brisset, Yoann Poher, Fabien Arnaud, Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UMR237-Aix Marseille Université (AMU)-Avignon Université (AU)

Subjects
Hydrology, 010506 paleontology, 010504 meteorology & atmospheric sciences, Flood myth, Reforestation, Fluvial, Climate change, Geology, 15. Life on land, 01 natural sciences, Natural (archaeology), Forest restoration, C2FN, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Soil retrogression and degradation, Physical geography, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Holocene, 0105 earth and related environmental sciences
Abstract

International audience; Understanding the role of climate and humans in generating mountain slope instability is crucial because such instability influences downstream fluvial activity and is a major threat to societies. Here, we use the sedimentary archive of Lake Allos (southeastern France), a mountain lake in the European Alps, to characterize mountain flood deposits and vegetation dynamics over the past 7000 yr. Our results support the interpretation of a critical threshold in catchment sensitivity to erosion at 1700 calibrated (cal.) yr B.P. (A.D. 250) probably resulting from long-term, uninterrupted impacts of human activity. The frequency and severity of floods increased dramatically after this date. These results demonstrate that underestimation of human impacts over the Holocene may pose a challenge to a clear understanding of past climate changes because paleoflood records are highly likely to have been affected by geomorphic thresholds. Natural reforestation since the end of the 19th century does not appear to be sufficient to induce a flood regime comparable to that which occurred prior to 1700 cal. yr B.P. This poses the question as to whether forest restoration in high-altitude environments is liable to foster a return to a low-erosion regime over the next decades, or whether the overall severity of soil degradation has been such as to preclude a return to previous conditions.

Published
2017
Full Text
View/download PDF

50. Monitoring des régimes thermiques des sols en montagne. Expériences alpines actuelles

Author

Emmanuel Malet, Jérôme Poulenard, and Philippe Choler

Subjects
monitoring, mountaine ecosystem, snow duration, alpine ecology, soil, temperature, température, sols, durée d'enseignement, écologie alpine, écosystème de montagne, General Medicine, 15. Life on land
Abstract

Recording the temporal and spatial (in three-dimension) changes in soil temperatures is not new. It is part of a long scientific tradition. The interest of monitoring the thermal regimes of soils today for questions of plant ecology but also for understanding the dynamics of storage/ release of soil organic matter is presented here in particular in mountain areas. After a brief presentation of the current techniques for monitoring these temperature regimes in soils (material, operational difficulties ...), the article presents some current alpine experiments of network of measurement of these regimes., L’enregistrement des évolutions temporelles et spatiales des températures des sols n’est pas une nouveauté. Il s’inscrit dans une longue tradition scientifique. Le suivi des régimes thermiques des sols apporte des éléments de réponse à des questions d’écologie végétale, mais permet aussi de mieux comprendre les dynamiques de stockage/ déstockage des matières organiques, en particulier en zone de montagne. Après une courte présentation des techniques de monitoring, l’étude de ces rédimes de températures dans les sols (matériel, difficultés opérationnelles) est illustrée par quelques expériences alpines en cours dans les Hautes-Alpes (vallon de Roche Noire) , en haute Tarentaise (profils de Bourg-Saint-Maurice) et dans le haut Faucigny (bassin versant du lac d’Anterne)., Poulenard Jerôme, Choler Philippe, Malet Emmanuel. Monitoring des régimes thermiques des sols en montagne. Expériences alpines actuelles. In: Collection EDYTEM. Cahiers de géographie, numéro 19, 2017. Monitoring en milieux naturels. Retours d’expériences en terrains difficiles. pp. 279-290.

Published
2017

Catalog

Books, media, physical & digital resources
See catalog results