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4. Hybridizing Geographically Weighted Regression and Multilevel Models: A New Approach to Capture Contextual Effects in Geographical Analyses.

Author

Feuillet, Thierry, Cossart, Etienne, Charreire, Helene, Banos, Arnaud, Pilkington, Hugo, Chasles, Virginie, Hercberg, Serge, Touvier, Mathilde, and Oppert, Jean Michel

Subjects
*MULTILEVEL models, *REGRESSION analysis, *AKAIKE information criterion, *INTRACLASS correlation, *BODY mass index, *FRENCH people
Abstract

Multilevel models are one of the main statistical methods used in modeling contextual effects in social sciences. A common limitation of these methods is the use pre‐set boundaries—usually administrative units—to define contexts, when these boundaries do not always match up with the "true" causally relevant contexts that may affect the outcomes of interest. In this study applied to the obesity geography in the Paris area (France), we propose a new spatially explicit two‐step procedure to tackle this methodological issue. The first step consists in estimating a geographically weighted regression model, then using it to reveal and delineate relevant nonstationarity‐based data‐driven spatial contexts, and finally including them as a random effect into a random slope multilevel model. In applying this hybrid methodology for modeling body mass index within a sample of 9,089 French adults, we demonstrate that it outperforms administrative‐based multilevel models in terms of decreasing Akaike information criteria, and is better at accounting for contextual effects through intraclass correlation coefficient and increasing slope variance. We suggest that this procedure might be generalized to quantitative geographical analyses involving contextual effects. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Sediments sources typology and mapping based on remote sensed data analysis

Author

Siccard, Vincent, Lissak, Candide, Gomez, Christopher, Cossart, Etienne, Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Identité et Différenciation de l’Espace, de l’Environnement et des Sociétés (IDEES), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Laboratory of Environmental Sedimentology and Sediment Hazards, Kobe University, and SICCARD, Vincent

Subjects
Sedimentary cascade, Landslide, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, (de)coupling, Mouvements de terrain, Télédétection, [SHS.GEO] Humanities and Social Sciences/Geography, Cascade sédimentaire, Machine learning, [SHS.GEO]Humanities and Social Sciences/Geography, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Remote sensing, (dé)couplage
Abstract

International audience; Before studying the sedimentary cascade from the point of view of connectivity, it is necessary to identifyand characterise the functioning of its components and elementary (de)couplings from the source zones.For this purpose, the open-air laboratory represented by the geomorphological disaster of 5-6 July in theAsakura region (Kyushu) allows us to study the sedimentary sources with an estimated sample of morethan 1500 mass movements triggered by the heavy rainfall during this High-Magnitude / Low-Frequency(HMLF) event.This work follows three stages: i) identification and mapping of source zones, ii) characterisation of theirnature and iii) estimation of their contribution to the sedimentary cascade.The mapping of source zones was carried out using multispectral satellite remote sensing combined witha machine-learning method. The images used are from the Pleiades sensor, which provides a very highresolution (VHR) spatial (0.50 m with Pansharpening) and spectral (RGB PIR). The semi-supervisedclassification was performed by the Random Forest learning algorithm using the Dzetsaka extension inQGIS. Bare soils on slopes are interpreted as instability zones subject to lateral transfer. The typology ofthe source areas was carried out in two steps. Firstly, the nature of the mass movements and therefore ofthe source zones was characterised using expert analysis methods associated with morphological criteria(length/width ratio). Secondly, the contribution of the source zones to the sedimentary cascade wasestimated using expert analysis methods and geomorphological criteria (e.g. types of contact, obstacles tosedimentary continuity, etc.).The mapped sedimentary sources represent 6.7 km² and 3.5% of the study area (193 km²). There is aspatial concentration of source areas in the southwest of the study area. The machine error of theclassification is about 97% and the operator error is 58%. The nature of the sedimentary sources ischaracterised by a broad spectrum of hydro-gravity processes that can be grouped mainly betweenslides/slope failures and flow-like landslide (e.g. debris avalanche, mud flow). These sedimentary sourcesactively contribute to the sedimentary cascade through generally efficient lateral and longitudinalcouplings despite local difficulties of sediment export due to decouplings or anthropogenic /environmental obstacles to sediment continuity.

Published
2022

11. Applications of graph theory to assess and compare sediment connectivity in three complex catchments

Author

Cossart, Etienne, Fressard, Matthieu, Reulier, Romain, Cossart, Etienne, Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN)

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

International audience

Published
2019

12. Soil erosion and sediment connectivity modelling in burgundy vineyards: case study of Mercurey, France

Author

Fressard, Mathieu, Cossart, Etienne, Lejot, Jérôme, Michel, Kristell, Perret, Franck, Christol, Aurélien, Mathian, Hélène, Navratil, Oldrich, Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon), Géographie-cités (GC (UMR_8504)), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SHS.GEO]Humanities and Social Sciences/Geography, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

13. SPATIAL PATTERNS OF VINEYARD LANDSCAPE EVOLUTION AND THEIR IMPACTS ON EROSION SUSCEPTIBILITY: RUSLE SIMULATION APPLIED IN MERCUREY (BURGUNDY, FRANCE) SINCE THE MID-20TH CENTURY.

Author

COSSART, ETIENNE, FRESSARD, MATHIEU, and CHAIZE, BRIAN

Subjects
*EROSION, *SOIL erosion, *SOIL management, *BURGUNDY wines, *VINEYARDS
Abstract

Erosion susceptibility in vineyards is approximately one order of magnitude above the reference level calculated for all agricultural activities, and preventing soil erosion is thus one of the most important environmental issues in vineyards. Spatially explicit models are necessary to address the coevolution of erosion susceptibility and anthropogenic practices because of the heterogeneous spatial patterns of erosion within vineyards. In this paper, we apply the RUSLE model to assess erosion susceptibility through time in a Burgundy vineyard (Mercurey) at a catchment scale (15 km²). The model is first calibrated with data acquired in 2015-2018. Second, erosion susceptibility during former stages (1953 and 1984) is compared to current reference frame. Such theoretical comparison considers that both C (land cover) and LS (Length-Slope) factors evolved through time. We hypothesize that such factors reveal both the land use evolution (especially agricultural land uses) and the development of a soil erosion management strategy based on the collection of sediments using roads, hedges and ditches. The current reference frame of erosion susceptibility calculated at catchment scale is about 9,152 t.yr-1. In the early 1980s a peak in erosion susceptibility is concomitant with vineyard expansion during the second half of the 20th century. Erosion susceptibility in vine parcels in 1984 is estimated to be 32% higher than current period. In the mid-20th century the spatial patterns of agricultural land use (patchwork of grasslands and vines, vines on moderately-rugged hillslopes) led to moderate rates of erosion susceptibility. At this stage, past level of erosion susceptibility is estimated to be 40% lower than current reference frame. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Tourists and local inhabitants representations of atmospheric pollution : towards a better understanding of a chronic risk in the Arve valley (France)

Author

Langlois de Septenville, William, Soto, Didier, Cossart, Etienne, Centre de Recherche de Géographie et Aménagement (Lyon 3) (CRGA), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Université Jean Moulin - Lyon 3 (UJML), Université de Lyon, Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon), and SOTO, Didier

Subjects
perceptions, alpine alley, [SHS.GEO] Humanities and Social Sciences/Geography, atmospheric pollution, [SHS] Humanities and Social Sciences, [SHS.GEO]Humanities and Social Sciences/Geography, risk system, [SHS]Humanities and Social Sciences
Abstract

International audience; This communication presents one aim of a starting PhD on pollution risk analysis. Here, we pay attention on one specific component of the pollution risk system related to the perceptions and representations of the tourists and local inhabitants in a French alpine valley. A general state of the art is presented, notably on pollutants representations as well as the need to integrate them in the overall risk assessment conceptual framework. More precisely, a specific focus is led on fundamental parameter of vulnerability and resilience. Then, study area is presented: it concerns specific threatened areas close to a major road, to draw a typology of inhabitants to survey.

Published
2016

15. Might short term rockglacier surface morphological changes be attributed to permafrost degradation ?

Author

Perrier, Romain, Cossart, Etienne, Fort, Monique, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
[SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDU] Sciences of the Universe [physics], Alpes du Sud, [SDU]Sciences of the Universe [physics], [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, glacier rocheux, surface, dégradation, changement morphologique, France, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS, permafrost
Abstract

International audience

Published
2016

16. Iceberg jam floods in Icelandic proglacial rivers: testing the self-organized criticality hypothesis

Author

Roussel, Erwan, Toumazet, Jean-Pierre, Philip, Marren, Cossart, Etienne, Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon), Université Jean Moulin - Lyon 3 (UJML), and Université de Lyon

Subjects
Islande, proglacial lakes, criticalité auto-organisée, Iceland, lacs proglaciaires, proglacial rivers, crues de barrage glaciels, [SHS.GEO]Humanities and Social Sciences/Geography, self-organized criticality, iceberg jam floods, cours d’eau proglaciaires
Abstract

International audience; In this paper, we describe a fluvial marginal process associated with the formation of iceberg jams in Icelandic proglacial lakes. The floods triggered by the release of these iceberg jams have implications for the geomorphic evolution of the proglacial fluvial system. The process of iceberg jam floods share some conceptual characteristics with Self-Organized Criticality (SOC) approach of complex systems. Using a simple numerical model and field observations, we test the hypothesis that iceberg jam floods exhibit SOC. Field observations and aerial photo-interpretations in southeastern Iceland demonstrate the occurrence of icebergs jam in ice-contact lakes. The mapping of the south Vatnajökull margins between 2003 and 2012 reveals an increase of the calving potentiality and a rise in the likelihood of iceberg jam flood occurrence. Based on the results of the numerical model and field observations, we suggest that iceberg jam floods should be recognized as a SOC phenomenon. Analysis of the simulated time-series show that the iceberg jam floods become less frequent and more similar in magnitude over time. This global trend is related to the gradual enlargement of the lake outlet channel.; Dans cet article, nous décrivons un processus uvial associé à la formation de barrages glaciels dans les lacs proglaciaires islandais. Les crues déclenchées par la rupture de ces barrages glaciels ont des implications sur l' évolution géomorphologique des systèmes uviaux proglaciaires. Le processus de crue de barrage glaciel partage des caractéristiques conceptuelles avec l' approche de criticalité auto-organisé (SOC) des systèmes complexes. A l' aide d'un modèle numérique simple et d' observations de terrain, nous testons l'hypothèse de criticalité auto-organisé pour les crues de barrage glaciel. Nos observations de terrain et nos travaux de photo-interprétations aériennes dans le sud de l'Islande témoignent de l' occurrence de barrages glaciels dans les lacs proglaciaires islandais. Le travail de cartographie des marges sud du Vatnajökull entre 2003 et 2012 montre une augmentation de la potentialité de vêlage et une hausse de la probabilité d' occurrence des crues de barrage glaciel. Sur la base de résultats issus du modèle numérique et de nos observations de terrain, nous suggérons que les crues de barrage glaciel devraient être considérées comme un phénomène caractérisé par la criticalité auto-organisé. L' analyse des séries temporelles simulées montre que les crues de barrage glaciel deviennent moins fréquentes et d'intensité similaire au cours du temps. Cette tendance globale est liée à la calibration progressive de la géométrie du chenal à l' exutoire du lac proglaciaire.

Published
2016

17. Torrential activity facing global change in Southern French Alps

Author

Lissak, Candide, Cossart, Etienne, Viel, Vincent, Fort, Monique, Arnaud-Fassetta, Gilles, Carlier, Benoit, UMR PRODIG, PUBLICATIONS, Sociétés et Changements Environnementaux - Adaptation de la société aux risques en montagne dans un contexte de changement global - - SAMCO2012 - ANR-12-SENV-0004 - Sociétés et Changements Environnementaux - VALID, Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Université Jean Moulin - Lyon 3 (UJML), Université de Lyon, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-12-SENV-0004,SAMCO,Adaptation de la société aux risques en montagne dans un contexte de changement global(2012), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Environnement Ville Société (EVS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Lyon (ENSAL)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Jean Moulin - Lyon 3 (UJML), and Université de Lyon-Université Lumière - Lyon 2 (UL2)-École normale supérieure - Lyon (ENS Lyon)

Subjects
Sediment transport in rivers, Sediment transfer, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geomorphological analysis, Alps France, Catchment, bassin-versant, Guil, Flood, [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, activité torrentielle, inondation, France, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, ComputingMilieux_MISCELLANEOUS, Alpes, cours d'eau
Abstract

International audience; In mountainous areas, especially in large river catchments with torrential tributaries, the sediment supply significantly increases the flood impacts in the valley bottoms. Within the framework of the SAMCO (ANR) project, dealing with the potential impacts of global changes (climate, ecosystem e.g. land use, socioeconomic system) on mountain hazards, we aim to a better understanding of Alpine river systems through the analysis of the sediment budgets. For estimating these budgets it implies the analysis of geomorphic processes contribution in the sediment production and transfers, and the identification of different sources, pathways and sinks. In the study area (Guil catchment, Southwest France), remobilisation of sediment accumulated in hillslope storage are largely determined by geomorphic extreme events (debris flow, shallow landslides, runoff). The contribution of these processes in sediment delivery to channel is the main objective of this poster. We propose a compartment analysis modelling in order to quantifying sediments fluxes and stores using system dynamics modelling. Our study aims at analysing the temporal composition of sediment cascade in the Peynin sub-catchement which highly contributes to sediment budget of the Guil river catchment. The initial phase of our study consists in identifying sediment sources and storage through geomorphological analysis and mapping. Then a conceptual model of the cascade can be generated (Schrott et al., 2003, Heckmann et al., 2008). Then we provide a stock & flow modeling based on System Dynamics to modelize sedimentary signals through time considering processes and storages interactions or connections.

Published
2016

18. From hydro-geomorphological mapping to sediment transfer evaluation in the Upper Guil Catchment (Queyras, French Alps)

Author

Lissak, Candide, Fort, Monique, Arnaud-Fassetta, Gilles, Mathieu, Alexandre, Malet, Jean-Philippe, Carlier, Benoit, Bétard, François, Cossart, Etienne, Madelin, Malika, Viel, Vincent, Charnay, Bérengère, Xavier, Bletterie, Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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), Université Paris Diderot - Paris 7 (UPD7), 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), and UMR PRODIG, PUBLICATIONS

Subjects
[SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, hydro-géomorphologie, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, Bassin-versant, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, transfert sédimentaire, France, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, ComputingMilieux_MISCELLANEOUS, Alpes, cours d'eau
Abstract

International audience

Published
2015

19. Sediment Budget Analysis and Hazard Assessment in the Peynin, a Small Alpine Catchment (Upper Guil River, Southern Alps, France)

Author

Carlier, Benoit, Arnaud-Fassetta, Gilles, Fort, Monique, Bouccara, Fanny, Sourdot, Grégoire, Tassel, Adrien, Lissak, Candide, Bétard, François, Cossart, Etienne, Madelin, Malika, Viel, Vincent, Charnay, Bérengère, Xavier, Bletterie, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Normandie Université (NU), 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), and UMR PRODIG, PUBLICATIONS

Subjects
[SDE] Environmental Sciences, Cours d'eau, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, bassin-versant, risque, budget sédimentaire, [SDE]Environmental Sciences, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, ComputingMethodologies_GENERAL, France, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, ComputingMilieux_MISCELLANEOUS, Alpes
Abstract

Poster; International audience

Published
2015

20. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

Author

Arnaud-Fassetta, Gilles, Lissak, Candide, Fort, Monique, Bétard, François, Carlier, Benoit, Cossart, Etienne, Madelin, Malika, Bouccara, Fanny, Viel, Vincent, Xavier, Bletterie, Charnay, Bérengère, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), 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), and UMR PRODIG, PUBLICATIONS

Subjects
[SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, lit de rivière, débris, Cours d'eau, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, France, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Alpes
Abstract

Poster; International audience; In mountainous areas, especially in large river catchments with torrential tributaries, the production and sediment transport significantly increase flood impacts in the valley bottoms. For a better understanding of Alpine river catchments considered as complex systems, our research focuses on the Guil River catchment (Queyras, Southern French Alps). This catchment is largely prone to catastrophic summer floods (June 1957 (> R.I. 100 yr), June 2000 (R.I. 30 yr)...) whose impact is amplified by the strong hillslope-channel connectivity, inducing important volume of sediment supply into the main channel network. Consequently to these last flood events, serious damages to infrastructure and buildings were caused; mostly at confluences with debris flow prone tributaries, but also along some specific reaches constrained by protection structures. In the frame of SAMCO (ANR 12 SENV-0004 SAMCO) project, for mountain hazard mitigation, one of our purposes is to understand the hydro-geomorphological functioning of this Alpine catchment. Part of our study deals with a better assessment of the sediment transfers, and is focused on adjacent sediment supply, i.e. from hillslope to channel, and from tributaries to the trunk river. First, we assess here the contribution of slopes to fine sediment supply, whereas coarse sediment supply from sub-catchments tributaries will be assessed (Pit-tags technique), in a second step (not detailed here), to better evaluate their contribution to the global sediment budget of the Guil river catchment. To quantify the actual sediment yield, airborne LiDAR (2012) and field surveys using Terrestrial Laser Scanning (TLS) have been carried out. While the Airborne LiDAR data cover the entire valley bottom of the Guil River, TLS measurement campaigns have been performed over three sites particularly affected by erosion and largely contributing to the Guil river sediment budget. The first site corresponds to a gorge section with direct connection of hillslope to the main channel network (Guil River). The second site is located in a sub-catchment, at the confluence of two productive torrents, and the third one is located along a torrent, in a small upstream sub-catchment. As preliminary results with the use of multi resolution data, erosion rates are presented. Four other TLS campaigns (2 per years) are planned and aim at associating erosion rates to seasonal hydro-climatic conditions. Our final goal is to produce an erosion susceptibility map that would include predisposing factors (geometry, colluvium and surficial deposits, vegetation cover…) and field measurements in order to characterize erosion conditions at the river catchment scale. As the primary objective of the SAMCO project, this susceptibility map combined with a vulnerability map, will help to develop a proactive resilience framework for enhancing the overall resilience of societies exposed to mountain risks .

Published
2015

21. Icelandic coastal mountains experienced post-LGM sackung processes: morphologic evidence from Tröllaskagi Mountains (Northern Iceland)

Author

Coquin, Julien, Mercier, Denis, Bourgeois, Olivier, Cossart, Etienne, Decaulne, Armelle, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)

Subjects
[SHS.GEO]Humanities and Social Sciences/Geography, Sackung, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

22. Sediment Dynamics and Channel Adjustments Following Torrential Floods in an Upper Alpine Valley (Guil River, Southern French Alps)

Author

Fort, Monique, Arnaud-Fassetta, Gilles, Bétard, François, Cossart, Etienne, Madelin, Malika, Lissak, Candide, Viel, Vincent, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), UMR PRODIG, PUBLICATIONS, Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN)

Subjects
River management, Sediment transfer, [SHS.GEO] Humanities and Social Sciences/Geography, Alpine valley, [SHS.GEO]Humanities and Social Sciences/Geography, Channel change
Abstract

International audience; In the upper reaches of Alpine valleys, the shaping of active channels appears mostlydependent upon hydroclimatic variability, as illustrated by the upper Guil River. In this valley,recent land-use changes have reduced the channel capacity of the Guil River, and increased thevulnerability of human installations to damage. In the frame of the implementation of a RiverScheme and a Flood Prevention Action Program, we try to improve our knowledge ofsediment transfers at the origin of disasters. Our analysis was carried after two high magnitudelow frequency hydroclimatic events (1957, 2000). It is based on desk and field data, accountfor active-channel width and area, sinuosity and braiding indexes, engineering structures andtheir variation in space and time. We show the major role played by the Guil tributaries insupplying debris to zones with important assets. Finally, we discuss about the difficulty toimplement efficient management tools at a local scale.

Published
2015

23. Use of terrestrial laser scanning (TLS) for monitoring geomorphic processes and sediment transfer in the Upper Guil Catchment (Queyras, French Alps)

Author

Lissak, Candide, Fort, Monique, Arnaud-Fassetta, Gilles, Malet, Jean-Philippe, Carlier, Benoit, Bétard, François, Cossart, Etienne, Madelin, Malika, Viel, Vincent, Charnay, Bérengère, Bletterie, Xavier, UMR PRODIG, PUBLICATIONS, Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), 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), 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), and Parc Naturel Régional du Quéras

Subjects
balayage laser terrestre, [SDE] Environmental Sciences, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDE]Environmental Sciences, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, France, tranfert sédimentaire, Queyras, Géomorphologie, bassin-versant, Alpes
Abstract

Poster; International audience; In mountainous areas, especially in large river catchments with torrential tributaries, the production and sediment transport significantly increase flood impacts in the valley bottoms. For a better understanding of Alpine river catchments considered as complex systems, our research focuses on the Guil River catchment (Queyras, Southern French Alps). This catchment is largely prone to catastrophic summer floods (June 1957 (> R.I. 100 yr), June 2000 (R.I. 30 yr)...) whose impact is amplified by the strong hillslope-channel connectivity, inducing important volume of sediment supply into the main channel network. Consequently to these last flood events, serious damages to infrastructure and buildings were caused; mostly at confluences with debris flow prone tributaries, but also along some specific reaches constrained by protection structures. In the frame of SAMCO (ANR 12 SENV-0004 SAMCO) project, for mountain hazard mitigation, one of our purposes is to understand the hydro-geomorphological functioning of this Alpine catchment. Part of our study deals with a better assessment of the sediment transfers, and is focused on adjacent sediment supply, i.e. from hillslope to channel, and from tributaries to the trunk river. First, we assess here the contribution of slopes to fine sediment supply, whereas coarse sediment supply from sub-catchments tributaries will be assessed (Pit-tags technique), in a second step (not detailed here), to better evaluate their contribution to the global sediment budget of the Guil river catchment. To quantify the actual sediment yield, airborne LiDAR (2012) and field surveys using Terrestrial Laser Scanning (TLS) have been carried out. While the Airborne LiDAR data cover the entire valley bottom of the Guil River, TLS measurement campaigns have been performed over three sites particularly affected by erosion and largely contributing to the Guil river sediment budget. The first site corresponds to a gorge section with direct connection of hillslope to the main channel network (Guil River). The second site is located in a sub-catchment, at the confluence of two productive torrents, and the third one is located along a torrent, in a small upstream sub-catchment. As preliminary results with the use of multi resolution data, erosion rates are presented. Four other TLS campaigns (2 per years) are planned and aim at associating erosion rates to seasonal hydro-climatic conditions. Our final goal is to produce an erosion susceptibility map that would include predisposing factors (geometry, colluvium and surficial deposits, vegetation cover…) and field measurements in order to characterize erosion conditions at the river catchment scale. As the primary objective of the SAMCO project, this susceptibility map combined with a vulnerability map, will help to develop a proactive resilience framework for enhancing the overall resilience of societies exposed to mountain risks .

Published
2015

24. Geomorphology and dating of the Vatn landslide and direct vicinity, Northern Iceland

Author

Decaulne, Armelle, Mercier, Denis, Cossart, Etienne, Coquin, Julien, Feuillet, Thierry, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
landslide, [SHS.GEO]Humanities and Social Sciences/Geography, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

25. Geomorphic impacts, age and significance of two giant landslide dams in the Nepal Himalayas: Ringmo‐Phoksundo (Dolpo District) and Dhampu‐Chhoya (Mustang District)

Author

Fort, Monique, Braucher, Regis, Bourles, Didier, Guillou, Valery, Rimal, Lila Nath, Gribenski, Natasha, Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-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), Remote Sensing, Department of Mines and Geology,Kathmandu, Department of Physical Geography [Stockholm], Stockholm University, Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), 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), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-AgroParisTech-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), 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), and UMR PRODIG, PUBLICATIONS

Subjects
[SDU] Sciences of the Universe [physics], orogènes, [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Himalayas, Népal, [SDU]Sciences of the Universe [physics], impact géomorpholoique, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, glissement de terrain, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, relief
Abstract

International audience; Large catastrophic slope failures have recently retained much attention in the northern dry Himalayas (Hewiitt 2009). They play a prominent role in the denudation history of active orogens at a wide range of spa7al and 7me scales (Korup & Clague, 2009), and they impact durably landforms and process evolution in upstream catchments. Their occurrence mostly results from three different potential triggers: earthquakes, post‐glacial debuttressing, and permafrost melting. We focus on two examplesof giant rock slope failures that occurred across and north of the Higher Himalaya of Nepal and assess their respective influence on the regional, geomorphic evolution.

Published
2014

26. Morphologic evidence for a sackung event in Tröllaskagi mountain (Northern Iceland)

Author

Coquin, Julien, Mercier, Denis, Bourgeois, Olivier, Cossart, Etienne, Decaulne, Armelle, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)

Subjects
sackung, [SHS.GEO]Humanities and Social Sciences/Geography, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

27. Focusing on the spatial nonstationarity of landslide predisposing factors in Northern Iceland. Do paraglacial factors vary over space?

Author

Feuillet, Thierry, Coquin, Julien, Mercier, Denis, Cossart, Etienne, Decaulne, Armelle, Jónsson, Helgi Páll, Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, and Decaulne, Armelle

Subjects
[SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

28. Sediment release and storage in early deglaciated areas

Author

Cossart, Etienne, Fort, Monique, and Cossart, Etienne

Subjects
Massif des Ecrins, paraglacial, [SHS.GEO] Humanities and Social Sciences/Geography, Little Ice Age, deglaciation, sediment budget
Abstract

Deglaciation in high mountain areas triggers a series of adjustments affecting the various geomorphic components of formerly glaciated catchments. Active processes, part of the ‘paraglacial' open system, release and transport sediments from formerly glacierized sources to catchment sinks. Such cascade sedimentary systems may be disrupted by temporary sediments traps. To evaluate the consequences of such traps on sediment export, several test areas were selected, where former glacial geometries and glacial retreat chronology were reconstructed from field data. Special attention is given to the link between the glacial margins and the glacio-fluvial systems. During glacial retreat, the presence of morainic ridges may temporarily interrupt the sedimentary cascade system, thus forcing local aggradation and change in the glacio-fluvial pattern. The volume of trapped sediments is controlled by the volume and the position of morainic ridges, while the storage residence time is strongly dependent upon the rate of moraine erosion. The ice surface elevation and its lowering control ice-contact storages, as well as sedimentary and water fluxes. The time lag between the rate of sediment accumulation on the valley floor and the rate of glacial shrinking influences the pattern and behaviour of drainage many decades after the peak in glacial melting.

Published
2008

29. Mapping permafrost at a regional scale: interpolation of field data by using GIS in the Upper Durance catchment (Southern French Alps)

Author

Cossart, Etienne, Perrier, R., Schwarz, M., Houée, S., Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Conseil Général des Hautes Alpes - VAL-PG

Subjects
Southern French Alps, water temperature, GIS modelling, [SHS.GEO] Humanities and Social Sciences/Geography, water resource, Permafrost, [SHS.GEO]Humanities and Social Sciences/Geography, rockglacier, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; Southern French Alps are mostly non-glaciated areas, but permafrost was locally evidenced at high altitudes (above 2800 m.a.s.l.). A clarification of permafrost spatial extent is currently needed because it constitutes a water resource. We suggest here a new method to map the permafrost. This method is based upon water temperature measurements, providing many observations (presence or absence) about permafrost in various physical settings. Such point-based data are integrated in a spatial database to realize an interpolation of the presence of permafrost. The study area is subdivided in many classes according to the incoming solar radiation. For each class, two thresholds are specified, one above which permafrost can possibly be observed, the other one above which permafrost can probably be observed. This method seems to complete previous models which were mostly based upon rockglacier inventories or BTS measurements. A map of permafrost extent is proposed, showing that it may possibly occur above 2500 m.a.s.l. in highly shielded areas. Some ice may be still stored within some footslope deposits, constituting a possible water resource.

Published
2008

30. Reconstitution de la géométrie d'un glacier disparu et modélisation des conséquences de sa disparition

Author

Cossart, Etienne and Cossart, Etienne

Subjects
Modèle Numérique de Terrain, SIG Raster, Durance, [SHS.GEO] Humanities and Social Sciences/Geography, volume glaciaire, déglaciation
Abstract

L'abondance des eaux de fusion et la recrudescence des mouvements de masse en contexte de déglaciation motivent la modélisation des conséquences géomorphologiques de la disparition d'un glacier. Nous proposons ici une méthode couplant le recueil de données géomorphologiques et le recours à la géomatique (SIG raster) pour reconstituer la géométrie d'un glacier disparu, puis quantifier le volume d'eaux de fusion libérées et l'ampleur de la décohésion post-glaciaire. Nous nous fondons pour cela sur l'exemple du glacier durancien (Briançonnais, Alpes Françaises du Sud) lors du Dernier Maximum Glaciaire.

Published
2007

31. Impacts of post glacial rebound on landsliding at a regional scale in Northern Iceland (Skagafjörður): spatial distribution and mechanisms involved

Author

Cossart, Etienne, Mercier, Denis, Decaulne, Armelle, Feuillet, Thierry, Jónsson, Helgi Páll, Sæmundsson, Þorsteinn, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Náttúrustofa Norðurlands vestra (NNv), and Ríkisins, Sveitafélag Skagafjarðar

Subjects
glacio-isostatic rebound, paraglacial, Iceland, Geomorphology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract

International audience; Paraglaciation has often been considered as a main predisposing factor in landslide occurrence; its consequences have been particularly well identified at a fine scale (especially on bedrock jointing). However, the impacts of paraglaciation on hillslope dynamics at a regional scale have never been discussed. We focus here on the Skagafjörður area (Northern Iceland) to compare the role of paraglaciation with that of classic factors (topography, lithology etc.) in landslide occurrence, using a spatial analysis (based upon a chi-square test). The results highlight that landslides are over-represented in areas where post-glacial rebound was at its maximum (i.e. there is a concentration of landslides in the northern part), which fits well with the first chronological benchmark we obtained. Thus, landslides occurred during the first half of the Holocene, when the post-glacial uplift was at its maximum. Finally, the mechanisms that link post-glacial rebound and landsliding are discussed. On the one hand, post-glacial rebound is identified as an efficient process to generate slope instabilities, leading to a concentration of landslides in the northern part of the fjord. On the other hand, the expected role of glacial debuttressing cannot be demonstrated here, although it is often considered one of the most important paraglacial influences on landsliding.

Published
2013

32. Toward a comprehensive paraglacial model: case studies from Iceland

Author

Mercier, Denis, Cossart, Etienne, Decaulne, Armelle, Feuillet, Thierry, Coquin, Julien, Bourgeois, Olivier, POCHAT, Stéphane, Jónsson, Helgi Páll, Sæmundsson, Þorsteinn, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)

Subjects
landslide, paraglacial, Iceland, geomorphology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography
Abstract

International audience; From the end of the Weichselian period and during the early Holocene, the landscape in Iceland underwent major changes. During this short-time interval, while glaciers were retreating from the lowlands, an exacerbation of geomorphic activity is noticed, due to lowering of the relative sea level, large glacial rivers flooding from the retreating ice margins and hillslope debutressing. As a consequence, many of the major paraglacial landforms that carved the Icelandic landscape are still visible nowadays. Two kinds of early Holocene paraglacial landforms can be identified in Iceland: (i) paraglacial denudation landforms (some slope failure deposits such as sackungs, rock avalanches and various other landslide types...), and (ii) paraglacial deposition landforms (alluvial fans, terraces, valley-train deposits, outwash plains or "sandurs" with outburst floods or "jökulhlaups", coastal deposits...). By using the sediment cascade framework, several paraglacial sources and sinks are also identified. This classical geomorphological approach privileges forms, processes to typify their temporal evolution through the Holocene. Some post-little ice age analogues in Iceland are also clear examples of such paraglacial evolution. To those external paraglacial dynamics we also propose to couple the consequences of the deglaciation to the internal earth dynamics (such as seismicity and volcanism, i.e. internal paraglacial effects). All around Iceland, glacio-isostatic rebound can explain the formation of numerous raised beaches, deltas, and strandflats. Also, an intense volcanic activity phase occurred within the early Holocene in Iceland, highlighting a link with the ice pressure release on the magma transfer. Based on our own researches and on literature review, we develop a spatial analysis at different time and space scales and propose a comprehensive paraglacial model, including external and internal earth dynamic implications.

Published
2013

33. The Vatn landslide, Skagafjördur, northern Iceland: early Holocene dating and Holocene palaeoenvironmental reconstitution potentialities

Author

Decaulne, Armelle, Mercier, Denis, Cossart, Etienne, Feuillet, Thierry, Coquin, Julien, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Landslide, Paraglacial, [SDU]Sciences of the Universe [physics], Iceland, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geomorphology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013

34. Impacts of post-glacial rebound on landslide spatial distribution at a regional scale in northern Iceland (Skagafjörður)

Author

Cossart, Etienne, Mercier, Denis, Decaulne, Armelle, Feuillet, Thierry, Jónsson, Helgi Páll, Sæmundsson, Þorsteinn, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
spatial analysis, para-glacial, Iceland, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography, post-glacial rebound, hillslope processes, mass movements
Abstract

International audience; In de-glaciated areas, para-glaciation (i.e. the conditioning of landscapes by prior glaciation) has often been considered a major predisposing factor in landslide occurrence; its consequences have been particularly well identified at a fine scale (especially on bedrock jointing). Hitherto, the relative impacts of para-glaciation on hillslope dynamics at a regional scale had nevertheless not been quantified statistically. We examine Skagafjörður area (northern Iceland) where landslides are widespread (at least 108 were mapped in an area of c. 3000km2).We compare the role of para-glaciation (debuttressing, influence of post-glacial rebound) with that of classic factors (topography, lithology, etc.) in landslide occurrence and location, using a spatial analysis based on a chi-square test. On the one hand, the results highlight that landslides are over-represented in areas where post-glacial rebound was at its maximum, with a stronger concentration of landslides in the northern part of the fjord. On the other hand, the distribution of landslides did not show any clear relationship with the pattern of glacial debuttressing. Tschuprow coefficient highlights that the influence of post-glacial rebound on landslide location is higher than the combined influence of slope gradient, curvature or geological structure. This result is supported by our initial evidence for the timing of landslides in the area: most landslides occurred during the first half of the Holocene, and a period of hillslope instability was initiated when the post-glacial uplift was at its maximum. Finally, the mechanisms that link post-glacial rebound and landsliding as well as the geomorphic impacts of landslides, are discussed.

Published
2013

35. Do deglaciated mountainslopes contribute significantly to paraglacial sediment fluxes

Author

Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
[SDU] Sciences of the Universe [physics], paraglaciaire, roche, [SDU.STU.AG] Sciences of the Universe [physics]/Earth Sciences/Applied geology, flux sédimentaire, [SDU]Sciences of the Universe [physics], [SHS.GEO] Humanities and Social Sciences/Geography, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, glissement de terrain, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, versant, [SHS.GEO]Humanities and Social Sciences/Geography, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology
Abstract

International audience; Sediment generation and pathways, as influenced by post-glacial collapse of mountain slopes in particular, arestudied in three steps. First, the processes involved in rock failure are identified and their possible influence onmass-movement locations at different spatial scales in various places is discussed. This comparison reveals avariable pattern of paraglacial landslide distribution, and allows the local/regional controlling parameters to beidentified. Second, the rate of triggering of mass-movement over time is roughly assessed in various settingsbased on a review of recently published data. This comparison aims to identify typical temporal-models forslope evolution through the time elapsed since deglaciation. Third, an attempt is made to assess the contributionof landsliding to the whole paraglacial cascading system by evaluating the somewhat contradictory findingsand assertions from previous authors: Some authors have argued for a high sediment yield at catchment sinksin relation to paraglacial landsliding (Church & Ryder, 1972; Ritter & Ten Brink, 1986), whereas others haveidentified that some long-lived sediment dams can occur after the deposition of a landslide mass, so that no or littlesediment exportation occurs (Korup, 2009; Cossart & Fort, 2008). We add to this debate by developing a typologyof geomorphic couples, between paraglacial landslides and other geomorphic processes, and present simulationsof sediment yield evolution since glacier disappearance

Published
2013

36. The Vatn landslide, Skagafjördur, northern Iceland: evidence of an early Holocene paraglacial crisis and impact on further slope development

Author

Decaulne, Armelle, Mercier, Denis, Cossart, Etienne, Thierry, Feuillet, Jónsson, Helgi Páll, Sæmundsson, Þorsteinn, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
Mass movement, paraglacial geomorphology, Iceland, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography, déglaciation
Abstract

International audience; The Vatn landslide is of modest size (estimated to 830,000 m3), and the deposit exhibits poor spatial dispersion and longitudinal runout. Its location in the Skagafjördur fjord, Northern Iceland (65 57,337'N, 19 23,900'W), evidences slope post-glacial development in the area. The interest of this landslide is found lower contact: the downslope part of the landslide deposit bumps on a stripe of raised beach, trapping a flat area at its northernmost boundary. The contact between the slide and the beach is open by a deep anthropogenic ditch. Analysis of (i) stratigraphic sections along the ditch, (ii) log section openings in the flat area at the slide contact and (iii) onto the slide deposit, offer numerous dating elements. Lower pits are rich in organic material and tephra layers (the oldest one, H4, is dated to 4,260 cal. BP), while the upper pit revealed little accumulation over the slide deposit surface, exhibiting only tephra layers separated by poor organic units. The combination of radiometric method and geochemical analysis of the tephra layers results in a good time constrain for the landslide occurrence, before 9070 86 cal. BP and 8677 181 cal. BP (oldest tree remnants). Such results reinforce the hypothesis of a major paraglacial geomorphologic crisis at the early Holocene time, leading to numerous slope failures following the last glacial maximum retreat (Mercier et al., in press, The Holocene). The presence of the raised beach at the lower contact with the landslide seems to indicate an occurrence later than 11,000-11,400 cal. BP (intrapolated age of the raised beaches located at 22-31 m a.s.l.), and suggests that isostatic rebound is a relevant triggering factor (Cossart et al, in press, Earth Surface Processes and Landforms). The lower pit section encompasses the full Holocene period, exhibiting a succession of organic layers and a very poor accumulation in minerogenic material. Those 2 m (i) document the palaeoenvironmental settings throughout the Holocene with potentialities for palynology and diatoms analyses; (ii) shows the decoupling of slope processes triggered in the rockwall upper part from the lower slope, as during the last ca. 10,000 years, no minerogenic material was archived below the landslide deposit.

Published
2013

37. Impacts of paraglaciation on landsliding at regional scale in Northern Iceland (Skagafjörður): spatial modelling and mechanisms involved

Author

Cossart, Etienne, Mercier, Denis, Decaulne, Armelle, Feuillet, Thierry, JÓNSSON Helgi, Páll, Sæmundsson, Þorsteinn, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), and Université de Nantes (UN)-Université de Nantes (UN)

Subjects
[SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013

38. Environmental geography: from field observations to mapping, from processes to risk management. A tribute to Prof. Monique Fort (University of Paris-Diderot)

Author

Arnaud-Fassetta, Gilles, Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Arnaud-Fassetta, Gilles

Subjects
Gestion des risques, Géographie de l'environnement, [SHS.GEO] Humanities and Social Sciences/Geography, Monique Fort, [SHS.GEO]Humanities and Social Sciences/Geography
Published
2013

39. Introduction to the special issue: 'Environmental geography: from field observations to mapping, from processes to risk management. A tribute to Prof. Monique Fort (University of Paris-Diderot)'

Author

Arnaud-Fassetta, Gilles, Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Arnaud-Fassetta, Gilles

Subjects
Gestion des risques, [SHS.GEO] Humanities and Social Sciences/Geography, Monique Fort, [SHS.GEO]Humanities and Social Sciences/Geography, ComputingMilieux_MISCELLANEOUS, Environnement
Abstract

International audience

Published
2013

40. Incision and aggradation in proglacial rivers: Post‐Little Ice Age long‐profile adjustments of Southern Iceland outwash plains.

Author

Roussel, Erwan, Toumazet, Jean‐Pierre, Marren, Philip M., Cossart, Etienne, Chenet, Marie, Grancher, Delphine, and Jomelli, Vincent

Subjects
GLACIAL Epoch, FLUVIAL geomorphology, PERIGLACIAL processes, LANDFORMS, GLACIERS
Abstract

The retreat of glaciers in response to climate warming leads to substantial changes in meltwater and sediment yield. Glacial shrinkage also induces the emergence and growth of proglacial margin landforms, which strongly affect water and sedimentary transfers from the glacier to the outwash plains. On a decadal timescale, field observations show that outwash plains of retreating glaciers typically exhibit proximal incision, which decreases in magnitude downstream and stops at an inflection point where aggradation begins. Nevertheless, there is a lack of knowledge about the rates and magnitude of this fluvial adjustment and the effects of the proglacial margin configuration on the temperance or the aggravation of this fluvial adjustment to glacier retreat. This paper investigates the proglacial rivers of 14 retreating glaciers in south‐east Iceland over a post‐Little Ice Age timescale, combining fluvial deposits mapping, lichenometric dating, and long‐profile measurements of proglacial fluvial terraces. Our results demonstrate that (a) proximal incision, associated with distal aggradation and downstream migration of the inflection point, is the dominant pattern of proglacial river response to post‐Little Ice Age glacier retreat in Iceland; (b) estimated mean rates of downstream migration of the inflection point range between 5 and 46 m·a−1; and (c) the downstream migration rate of the inflection point is positively correlated with the proportion of proglacial lakes within the glacier foreland. These findings suggest that proglacial margins dominated by proglacial lakes intensify the rates of proximal incision and inflection point migration. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
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41. How might sediment connectivity change in space and time?

Author

Cossart, Etienne, Viel, Vincent, Lissak, Candide, Reulier, Romain, Fressard, Mathieu, and Delahaye, Daniel

Subjects
SEDIMENTS, SOIL mechanics, SEDIMENTOLOGY, GEOMORPHOLOGY, ENVIRONMENTAL impact analysis
Abstract

Abstract: Many authors focus on the concept of sediment connectivity to predict the sedimentary signal delivered at catchment outlets. In this framework, the sedimentary signal is seen as an emergent aggregation of local links and interactions. The challenge is then to open black boxes that remain within a sediment cascade, which requires both accurate geomorphic investigations in the field (reconstruction of sequences of geomorphic evolution and description of sediment routes) and the development of tools dedicated to the modeling of sediment cascades. On the basis of study cases in various environmental regimes (high‐energy mountainous environment and agricultural lowland catchments), in this paper, we (a) exhibit some spatial and temporal paradoxes in terms of sediment delivery and (b) develop various modeling procedures to test some hypothesis of interpretations. These modeling approaches explore different components of sediment connectivity at the catchment scale, including graph theory, agent‐based modeling, and differential equations. Each protocol is chosen according to the scientific objective and how the geomorphological system is simplified. Collectively, the results show that connectivity is an efficient conceptual framework with which to predict how a sediment cascade may transmit (or not) a perturbation throughout the system, including local perturbations (local sediment input, removal of a reservoir, etc.) and perturbations due to external‐boundary forces. [ABSTRACT FROM AUTHOR]

Published
2018
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42. Dating post-glacial geoprocesses in Skagafjörður (Central North Iceland) by geomorphology, tephrochronology, radiocarbon and cosmogenic nucleids

Author

Decaulne, Armelle, Mercier, Denis, Cossart, Etienne, Feuillet, Thierry, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Université Paris-Sorbonne - Paris 4 - UFR Géographie et Aménagement (UP4 UFR GA), Université Paris-Sorbonne (UP4), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Laboratoire Dynamiques Sociales et Recomposition des Espaces (LADYSS), Université Paris Diderot - Paris 7 (UPD7)-Université Paris Nanterre (UPN)-Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Panthéon-Sorbonne (UP1)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris Nanterre (UPN)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Panthéon-Sorbonne (UP1)-Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris Nanterre (UPN)-Université Paris Diderot - Paris 7 (UPD7), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Islande, Post-glaciaire, [SHS.GEO]Humanities and Social Sciences/Geography, Skagafjörður, Géomorphologie, Géoprocessus, ComputingMilieux_MISCELLANEOUS, Tephrochronologie, Radiocarbone, [SHS]Humanities and Social Sciences
Abstract

International audience

Published
2012

43. Typology of sorted patterned ground sites in Skagafjörður (Northern Iceland) by using a factor analysis of mixed data

Author

Feuillet, Thierry, Mercier, Denis, Decaulne, Armelle, Cossart, Etienne, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-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), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Normandie Université (NU)-Normandie Université (NU)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), and Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE)

Subjects
Typology, Ground sites, Northern Iceland, Factor analysis method, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography, Skagafjörður, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2012

44. Reconstructing chronology of post-glacial mass movements in the Skagafjörður, Northern Iceland (Northern Iceland) from radiocarbon, tephrochronological and geomorphological results

Author

Mercier, Denis, Decaulne, Armelle, Cossart, Etienne, Feuillet, Thierry, Sæmundsson, Þorsteinn, Jónsson, Helgi Páll, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Normandie Université (NU)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), and Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE)

Subjects
Post-glacial mass movements, Tephrochronological results, Geomorphologicalr esults, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography, Skagafjörður
Abstract

International audience; Since the last major deglaciation, about 12-10,000 years ago, paraglacial landforms widely occurred in fjord and mountain areas; mass movements such as rock-slope failure, rock avalanches, rockslides, sackungs, etc., are common (Dikau et al., 1996; Ballantyne, 2008). In north Iceland, numerous mass movements' landforms occurred, mostly in areas within Tertiary basalt formation, in a landscape characterized by steep slopes and overdeepened glacial valleys. Many of those landforms can be observed in the Vestfirðir peninsula, in central North Iceland, and in Eastern Iceland. Jónsson (1957) made some early descriptions of such landforms. He concluded that most of those landforms were formed during or shortly after the last deglaciation, in Early Holocene; at the time of these first observations, results on absolute dating were lacking. Recently, several landslides have been studied in the Skagafjörður area (Decaulne et al., 2010, Mercier et al., 2011). The aim of this study is to date several landslides in the Skagafjörður area, by combining several proxies, e.g. radiocarbon dating, teprhochronology, raised beaches. We present here the result on one of those, the Höfðahólar case-study. - The material originating from the Höfðahólar rock avalanche partly buried a succession of raised beaches. Raised beaches out in the Skagi peninsula, just west of the study area, exceeding 65 m a.s.l., have been dated older than 12,000 yr B.P. (Rundgren et al., 1997). Beaches between 43 and 50 m a.s.l. have been dated to 11,300-9,900 yr B.P. and beaches at 22-31 m a.s.l. between 9900 and 9600 yr B.P. Regression below the present sea level occurred at 9,000 yr BP. As the rock avalanche deposit does not display visible evidence of being impacted by the glacio-isostatic rebound, it is believed to be younger than 9,000 yr B.P. - Tephra layers, occurring in a peat bog on top of the rock avalanche material date the avalanche older than 4,500 yr B.P., as the H4 tephra layer is found at 140 cm depth. - 14C dating of birches (Betula sp.) trunk, branch and root pieces found 80 cm deeper than the H4 layer provide 6,070 yr B.C. calibrated age. This period, around 8,000 yr B.P. is known as the "early birch periode" in Iceland, known to have been warm and favouring tree development (Einarsson 1991, Óladóttir et al. 2001, Langdon et al., 2010). Thus, the Höfðahólar rock avalanche event occurred between 9,000 B.P. (youngest beaches) and 8,000 B.P. (14C oldest dating). Such results comfort Jónsson idea, proposing the occurrence of such landslide as the result of a rapid paraglacial crisis following the deglaciation period, due to the combined effects of glacial oversteepening, supply water throughout the lava piles during glacial melting, and glacio-isostatic uplift.

Published
2012

45. Sediment budget in a Himalayan Valley (Middle Kali Gandaki, Nepal)

Author

Fort, Monique, Cossart, Etienne, UMR PRODIG, PUBLICATIONS, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nepal, [SHS.GEO] Humanities and Social Sciences/Geography, [SHS.GEO]Humanities and Social Sciences/Geography, Sediment budget, Himalayan Valley
Published
2012

46. Glacier variation in the Massif des Ecrins during the 20th century: spatial and temporal patterns

Author

Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
[SHS.GEO] Humanities and Social Sciences/Geography, [SHS.GEO]Humanities and Social Sciences/Geography
Published
2011

47. Dating of a rock avalanche in Skagafjörður,, Northern Iceland: pieces of evidence of a paraglacial origin

Author

Mercier, Denis, Decaulne, Armelle, Cossart, Etienne, Feuillet, Thierry, Sæmundsson, Þorsteinn, Jónsson, Helgi Páll, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Náttúrustofa Norðurlands vestra (NNv), Ríkisins, Sveitafélag Skagafjarðar, Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Mercier, Denis

Subjects
[SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO] Humanities and Social Sciences/Geography, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SHS.GEO]Humanities and Social Sciences/Geography
Abstract

International audience; The Skagafjörður area counts several large slope mass movements especially on the eastern side of the fjord. They are initiated from the top of the rockwall where a more or less developed scars are still observed. A significant number of those landforms have been described by Jónsson (1957), who interpreted those landforms as a result of post-glacial rockwall debuttressing, following the shrinking of the large ice bodies in the early Holocene. However, no attempt of dating has yet been carried out on the debris masses. The aims of this research are to discuss its possible paraglacial origin by combining four dating benchmarks: (i) the dating of a succession of raised beaches on which the rock avalanche material lies. The higher beaches, exceeding 65 m a.s.l., have been dated older than 12000 BP. Beaches between 43 and 50 m a.s.l. have been dated older than 11300 and 9900 BP and beaches at 22-31 m a.s.l. between 9900 and 9600 BP. Regression below the present sea level occurred about 9000 BP (Rundgren et al., 1997). As the rock avalanche deposit does not display visible evidence of being impacted by the glacio-isostatic rebound (no inherited sea cliffs are seen at higher elevation than the actual sea level), we estimate the rock avalanche occurred later than 9000 BP. (ii) the tephrochronological dating from the excavations made in the upper part of the mass, where peat areas developed since the setting of the rock avalanche goes back to 4500 years BP, with the H4 Hekla acid white thick layer found at 140 cm depth. The deposits from Hekla are well known in the area, and the five most common ash layers were discovered in the opened section, providing a significant time marker. (iii) 14C dating of birches (Betula sp.) trunk and branches pieces found 80 cm below the H4 layer. The results are not yet available, but the period around 8000 BP is considered at those latitudes as a warm period, favourable to tree development. (iv) basalt samples were collected on the rock avalanche deposit, at various elevations and settings on the deposit, to provide Cosmic Ray Exposure ages. To specify the age of the landslide, we will measure 10Be within the pyroxene minerals constituting the basalt. Beryllium isotopic ratios will be measured at the laboratory of CEREGE by Accelerator Mass Spectrometry. The results are in progress. Collectively, those chronological benchmarks constrain the trigerring of the rock avalanche event between 9000 BP (present-day sea-level) and 4500 BP (tephrochronology oldest dating). The finding of a large amount of wood long before the H4 tephra layer suggests that the occurrence of the rock avalanche was closer to the oldest extremity of this time period (so-called early birch period, just around 9000 BP, according to Einarsson 1991, and Óladóttir et al. 2001). Such results comfort the Ólafur Jónsson idea, proposing the occurrence of such mass movement as the result of a rapid paraglacial crisis following the deglaciation period, due to the combined effects of rockwall debuttressing and glacio-isostatic uplift. The cosmogenic and 14C results will provide a more accurate data for the chronological scenario. References Einarsson Þ., 1991. Geology of Iceland, rocks and landscape. Mál og Menning, Reykjavík, 309 p. Jónsson Ó., 1957. Skriðuföll og snjóflóð, Bókaútgáfan norðri, t. 1, 141 p. Óladóttir R., Schlyter P. & Haraldsson H., 2001. Simulating Icelandic vegetation cover during the Holocene, implication for long-term land degradation. Geografiska Annaler 83, 203-215. Rundgren M., Ingólfsson Ó., Björk S., Jiang H. & Hafliðason H., 1997. Dynamic sea-level change during the last deglaciation of northern Iceland. Boreas 26: 201-215.

Published
2011

48. Spatial extent of Permafrost in the Southern Alps : Modeling from spring water temperature sources and topoclimatic factors

Author

Perrier, Romain, Cossart, Etienne, Fort, Monique, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
Topoclimatic factors, [SHS.GEO] Humanities and Social Sciences/Geography, Permafrost, [SHS.GEO]Humanities and Social Sciences/Geography, Southern Alps
Published
2011

49. Natural hazards, road development, increased vulnerability and risks in the Nepal Himalayas

Author

Fort, Monique, Cossart, Etienne, Arnaud-Fassetta, Gilles, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
[SHS.GEO] Humanities and Social Sciences/Geography, [SHS.GEO]Humanities and Social Sciences/Geography
Published
2011

50. Landslide hazards, settlements sites and development in the Nepal Himalayas

Author

Fort, Monique, Cossart, Etienne, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and UMR PRODIG, PUBLICATIONS

Subjects
[SHS.GEO] Humanities and Social Sciences/Geography, [SHS.GEO]Humanities and Social Sciences/Geography
Published
2011

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