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Equipe Dynamiques Géoenvironnementales Actuelles

ACL - Articles dans des revues à comité de lecture


  • Casado Ana, Peiry Jean-Luc et Campo Alicia M.« Geomorphic and vegetation changes in a meandering dryland river regulated by alarge dam, Sauce Grande River, Argentina », Geomorphology. DOI : 10.1016/j.geomorph.2016.05.036.
    Résumé : This paper investigates post-dam geomorphic and vegetation changes in the Sauce Grande River, a meandering dryland river impounded by a large water-conservation dam. As the dam impounds a river section with scarce influence of tributaries , sources for fresh water and sediment downstream are limited. Changes were inspected based on (i) analysis of historical photographs/imagery spanning pre-(1961) and post-dam (1981, 2004) channel conditions for two river segments located above and below the dam, and (ii) field survey of present channel conditions for a set of eight reference reaches along the river segments. Whilst the unregulated river exhibited active lateral migration with consequent adjustments of the channel shape and size, the river section below the dam was characterized by (i) marked planform stability (93 to 97%), and by (ii) vegetation encroachment leading to alternating yet localized contraction of the channel width (up to 30%). The present river displays a moribund, stable channel where (i) redistribution of sediment along the river course no longer occurs and (ii) channel forms constitute a remnant of a fluvial environment created before closing the dam, under conditions of higher energy. In addition to providing new information on the complex geomorphic response of dry-land rivers to impoundment, this paper represents the very first geomorphic assessment of the regulated Sauce Grande and therefore provides an important platform to underpin further research assessing the geomorphic state of this highly regulated dryland river.
    Mots-clés : Dryland rivers, flow regulation, Geomorphic changes, Paso de las Piedras Dam, Sauce Grande River, Vegetation changes.

  • Maleval Véronique, Destombes Pierre-Brieuc et Astrade Laurent« Diagnostic et propositions d'actions relatifs à l'érosion des berges du Léman sur la commune de Thonon-les-Bains (Haute-Savoie, France) », Physio-Géo - Géographie Physique et Environnement (, 10/2016, p. 20-43. (Physio Géo - Géographie Physique et Environnement).
    Mots-clés : erosion, Géomorphologie, geomorphology, Léman, Léman., protection, rate, rivage, sedimentation, shoreline, vitesse.

  • Poiraud Alexandre, Chevalier Mylène, Claeyssen Bertrand, Biron Pierre-Eymard et Joly Bertrand« From geoheritage inventory to territorial planning tool in the Vercors massif (French Alps): Contribution of statistical and expert cross approaches », Applied Geography, 71, p. 69-82. DOI : 10.1016/j.apgeog.2016.04.012.
    Résumé : Geoheritage is a concept derived from the geosciences, initially referring to the preservation of geoscientific objects. This concept is now used in local or regional development, especially for promoting a territory via the supply of geotouristic services for example. In this way, geoheritage covers the domains of geography, social sciences and strategy planning. In these types of project, geoheritage is considered as a natural resource, which implies a good knowledge of the location and characteristics of the resources concerned. For this purpose, we require an inventory. In this paper, we explore a methodology to draw up a geoinventory adapted to the territorial project of Vercors as well as an analytical approach mixing multivariate statistics and expert knowledge to produce an objective and suitable territorial diagnosis. The statistical approach is PCA-based whereas the heuristic approach combines a blind-test with two non-expert teams and a heuristic classification by two experts. This heuristic approach was based only on visualization of radar chart. Despite the inherent subjectivity of such a methodology, this statistical-expert cross approach provides a consensual classification of the 79 listed geosites and a deeper understanding of the major components making up the inventory. This classification forms the basis of a territorial analysis which proposes the creation of 5 thematic spaces (glacio-tectonic, peleogeomorphology, hydrogeology, morpho-tectonic and stratigraphy) across the whole massif as new territories for the development of geoeducation and geotourism. Finally, the territorial strategy considers the Vercors massif as an important dynamic outdoor museum dedicated to environmental education based on a major contribution arising from the analysis of geoheritage.
    Mots-clés : Expert analysis, French Alps, Geoheritage, Geotourism, Multivariate statistics, Territorial planning.

  • Roussel Erwan, Toumazet Jean-Pierre, Marren Philip M. et Cossart Etienne« Iceberg jam floods in Icelandic proglacial rivers: testing the self-organized criticality hypothesis », Géomorphologie : relief, processus, environnement, vol. 22 – 1/2016, p. 37-49. DOI : 10.4000/geomorphologie.11229.

  • Arthur Messerli et Larrue Sébastien« Effets de l’arbuste envahissant Rhododendron ponticum L. sur quelques espèces indigènes de l’île de Rùm (Ecosse du nord-ouest) », Revue d'Ecologie (La Terre et la Vie), 70 (Spécial Espèces Invasives), p. 68-79.
    Résumé : Introduit dans les îles britanniques en 1763 pour sa valeur ornementale, Rhododendron ponticum (L.) est aujourd’hui un arbuste naturalisé dans tout le Royaume-Uni. Cette espèce est considérée comme l’une des plus envahissantes de Grande-Bretagne. Cette étude tente in situ de mettre en évidence les effets de Rhododendron ponticum sur quelques espèces indigènes de l’île de Rùm (Nord-Ouest de l’Écosse, Grande Bretagne) où les gestionnaires se sont notamment engagés dans des programmes de reboisement en espèces ligneuses indigènes. Nous avons comparé la diversité végétale (i.e., la richesse spécifique, l’abondance, et les indices de diversité de Shannon, Simpson et d’équitabilité) dans (1) des placettes de 100 m² situées en landes envahies et non envahies par Rhododendron ponticum, et (2) des îlots de sous-bois formés par des individus d’Ilex aquifolium (indigène) versus Rhododendron ponticum (introduite). Les placettes envahies par Rhododendron ponticum présentent globalement des indices de Shannon, Simpson et une équitabilité plus faibles. Dans les îlots, on observe la même tendance, les indices de diversité sont plus faibles sous les îlots à Rhododendron ponticum que sous ceux à Ilex aquifolium. Ces résultats laissent à penser que Rhododendron ponticum perturbe l’établissement des espèces indigènes avec notamment une moindre abondance des ptéridophytes telles que Dryopteris dilatata et Dryopteris filix-mas. Par ailleurs, les îlots à Ilex aquifolium présentent une diminution significative dans l’abondance de Rhododendron ponticum en sous-bois. Ilex aquifolium devrait donc accompagner les programmes de reboisement en espèces indigènes afin de diminuer l’invasion de Rhododendron ponticum en sous-bois.

  • Bartout Pascal, Touchart Laurent, Terasmaa Jaanus, Choffel Quentin, Marzecova Agata, Koff Tiiu, Kapanen Galina, Qsair Zoubida, Maleval Véronique, Millot Camille, Saudubray Julien et Aldomany Mohammad« A new approach to inventorying bodies of water, from local to global scale », Die Erde, 146 (4), p. 245-258. DOI : 10.12854/erde-146-.
    Mots-clés : bodies of water, Inventory, lake, pond, scale.

  • Beauger Aude, Delcoigne Arnaud, Voldoire Olivier, Serieyssol Karen K. et Peiry Jean-Luc« Distribution of diatom, macrophyte and benthic macroinvertebrate communities related to spatial and environmental characteristics: the example of a cut-off meander of the River Allier (France) », Cryptogamie, Algologie, 36 (3), p. 1-33. DOI : 10.7872/crya/v36.iss3.2015.1.
    Résumé : Currently, a consensus has been reached to protect and restore cut-off meanders. Therefore, it is important to understand how these wetlands function. To our knowledge, the spatial and temporal distribution of both benthic diatoms and macroinvertebrates, associated with macrophytes communities, linked to the geomorphology, has not been studied extensively. In the upstream and intermediate zones, the low water temperature and the high conductivity revealed a connection with the groundwater. Moreover, the geomorphological riffle characterizing the intermediate zone created the same downwelling and upwelling processes as in running water, with a groundwater/hyporheic/surface water ecotone and produced physico-chemical differences between the upstream and the downstream zones and thereby modify the diatom, macroinvertebrate and macrophyte distribution. Downstream, water input from the main channel of the Allier River allowed the development of taxa observed in the River. All these hydrological connections and the sedimentation modified the physical, chemical and geomorphological characteristics, thereby, creating a gradient of water quality, influencing the distribution of the biotic communities.
    Mots-clés : /, cut-off, diatoms, geomorphology, Macroinvertebrates, macrophytes, meander, water.

  • Casteller Alejandro, Stoffel Markus, Crespo Sebastian, Villalba Ricardo, Corona Christophe et Bianchi Emilio« Flash floods in the Patagonian Andes: A dendrogeomorphological approach. », Geomorphology, 228, p. 116-123. DOI : 10.1016/j.geomorph.2014.08.022.
    Résumé : Flash floods represent a significant natural hazard in small mountainous catchments of the Patagonian Andes and have repeatedly caused loss to life and infrastructure. At the same time, however, documentary records of past events remain fairly scarce and highly fragmentary in most cases. In this study, we therefore reconstruct the spatiotemporal patterns of past flash flood activity along the Los Cipreses torrent (Neuquén, Argentina) using dendrogeomorphic methods. Based on samples from Austrocedrus chilensis, Pseudotsuga menziesii, and Nothofagus dombeyi, we document 21 flash flood events covering the period A.D. 1890–2009 and reconstruct mean recurrence intervals of events at the level of individual trees being impacted, which varies from 4 to 93 years. Results show that trees tend to be older (younger) in sectors of the torrent with gentler (steeper) slope gradients. Potential triggers of flash floods were analyzed using daily temperature and precipitation data from a nearby weather station. Weather conditions leading to flash floods are abundant precipitations during one to three consecutive days, combined with temperatures above the rain/snow threshold (2 °C) in the whole watershed.
    Mots-clés : Austrocedrus chilensis, Dendrogeomorphology, Nothofagus dombeyi, Patagonian Andes, Pseudotsuga menziesii.

  • Corenblit Dov, Baas Andreas, Balke Thorsten, Bouma Tjeerd, Fromard François, Garófano-Gómez Virginia, González Eduardo, Gurnell Angela M., Hortobágyi Borbála, Julien Frédéric, Kim Daehyun, Lambs Luc, Stallins J. Anthony, Steiger Johannes, Tabacchi Eric et Walcker Romain« Engineer pioneer plants respond to and affect geomorphic constraints similarly along water-terrestrial interfaces world-wide », Global Ecology and Biogeography, 24 (12), p. 1363–1376. DOI : 10.1111/geb.12373.
    Résumé : AIM Within fluvial and coastal ecosystems world-wide, flows of water, wind and sediment generate a shifting landscape mosaic composed of bare substrate and pioneer and mature vegetation successional stages. Pioneer plant species that colonize these ecosystems at the land–water interface have developed specific traits in response to environmental constraints (response traits) and are able to modify habitat conditions by modulating geomorphic processes (effect traits). Changes in the geomorphic environment under the control of engineer plants often feed back to organism traits (feedback traits), and thereby ecosystem functioning, leading to eco-evolutionary dynamics. Here we explain the joint foundations of fluvial and coastal ecosystems according to feedback between plants and the geomorphic environment. LOCATION Dynamic fluvial and coastal ecosystems world-wide. METHOD Drawing from a pre-existing model of ‘fluvial biogeomorphic succession’, we propose a conceptual framework showing that fluvial and coastal ‘biogeomorphic ecosystems’ are functionally similar due to eco-evolutionary feedbacks between plants and geomorphology. RESULTS The relationships between plant traits and their geomorphic environments within different fluvial and coastal biogeomorphic ecosystems are identified and classified within a framework of biogeomorphic functional similarity according to three criteria: (1) pioneer plants develop specific responses to the geomorphic environment; (2) engineer plants modulate the geomorphic environment; (3) geomorphic changes under biotic control within biogeomorphic ecosystems feed back to organisms. MAIN CONCLUSIONS The conceptual framework of functional similarity proposed here will improve our capacity to analyse, compare, manage and restore fluvial and coastal biogeomorphic ecosystems world-wide by using the same protocols based on the three criteria and four phases of the biogeomorphic succession model.
    Mots-clés : biogeomorphic ecosystem, biogeomorphic succession, coastal dune, eco-evolutionary dynamics, ecosystem engineer, mangrove, niche construction, plant trait, river, salt marsh.

  • Corenblit Dov, Davies Neil S., Steiger Johannes, Gibling Martin R. et Bornette Gudrun« Considering river structure and stability in the light of evolution: feedbacks between riparian vegetation and hydrogeomorphology », Earth Surface Processes and Landforms, 40 (2), p. 189-207. DOI : 10.1002/esp.3643.
    Résumé : River ecological functioning can be conceptualized according to a four-dimensional framework, based on the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical and temporal dimensions of rivers. Contemporary riparian vegetation responds to river dynamics at ecological timescales, but riparian vegetation, in one form or another, has existed on Earth since at least the Middle Ordovician (c. 450 Ma) and has been a significant controlling factor on river geomorphology since the Late Silurian (c. 420 Ma). On such evolutionary timescales, plant adaptations to the fluvial environment and the subsequent effects of these adaptations on fluvial sediment and landform dynamics resulted in the emergence, from the Silurian to the Carboniferous, of a variety of contrasted fluvial biogeomorphic types where water flow, morphodynamics and vegetation interacted to different degrees. Here we identify several of these types and describe the consequences for biogeomorphic structure and stability (i.e. resistance and resilience), along the four river dimensions, of feedbacks between riparian plants and hydrogeomorphic processes on contrasting ecological and evolutionary timescales. This article is protected by copyright. All rights reserved.
    Mots-clés : ecosystem engineer, ecosystem resistance and resilience, fluvial biogeomorphic succession, functional effect and response traits, niche construction, riparian vegetation, scale-dependant feedback, vegetation evolution.

  • Corona Christophe, Saez Jérôme Lopez, Stoffel Markus, Rovéra Georges, Edouard Jean-Louis et Guibal Frédéric« Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps », Frontiers in Ecology and Evolution, 2 (82), p. 10.3389/fevo.2014.00082. DOI : 10.3389/fevo.2014.00082.
    Résumé : Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven relict stands of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitude to a P. uncinata stand located at the alpine treeline. Two detrending procedures are used to reveal high- and low-frequencies embedded in annually resolved ring-width series. Growth response of P. uncinata to instrumental temperature and precipitation data is investigated by means of moving response function analyses. Results show an increase in the sensitivity of tree-ring widths to drought during previous summer in both stands. At the treeline stand, an increasing response to fall temperature is observed whereby fall temperature and radial tree growth increased in two synchronous steps around ~1930 and from ~1980-present. At the low-altitude stand, P. uncinata appears more drought sensitive and exhibits a sharp growth decline since the mid-1980s, coinciding with increasing summer temperatures. Growth divergence between the two stands can be observed since the mid-1980s. We argue that the positive growth trend at the high-altitude stand is due to increasing fall temperatures which would favor the formation of metabolic reserves in conjunction with atmospheric CO2 enrichment that in turn would facilitate improved water use efficiency. At the relict low-altitude stand, in contrast, it seems that improved water use efficiency cannot compensate for the increase in summer temperatures.
    Mots-clés : climate change, dendroclimatology, elict pine stand, French Alps, response functions, tree-growth decline.

  • Garófano-Gómez Virginia, Corenblit Dov Jean-François, Steiger Johannes, Moulia Bruno B., Ploquin Stéphane, Chaleil Patrice, Forestier Olivier, Evette André, Hortobágyi Borbála et Lambs Luc« Response of black poplar (Populus nigra L.) to hydrogeomorphological constraints: a semi-controlled ex situ experiment ».
    Mots-clés : Mechanical constraints, Populus nigra L, positive niche construction, response traits, sediment burial.

  • Larrue Sébastien, Butaud J.-F., Dumas P. et Ballet S.« Native plant species richness on Eastern Polynesias remote atolls: Which abiotic factors influence its spatial pattern? », Progress in Physical Geography, p. 1–23. DOI : 10.1177/0309133315615804.
    Résumé : Which abiotic factors influence the number of native plant species on remote atolls is an important question to understand better the spatial pattern of the species observed on these low and vulnerable coral islands. However, this issue is still very poorly documented, often due to human degradation, partial botanical surveys or the difficult geographic access of remote atolls for researchers. The remote atolls of Eastern Polynesia, which are among the most isolated in the world, are of great interest for studies of native species’ distribution due to their isolation, low human density and urbanisation. In this study, we selected 49 remote atolls of Eastern Polynesia with complete botanical surveys to test the relative influence of eight abiotic factors on native plant species richness (i.e. indigenous and endemic species). Abiotic factors used as potential predictors included atoll area (km2), shoreline length (km), atoll elevation (m) and index of isolation (UNEP), but also the coastal index of the atoll (Ic ), the distance to the nearest similar atoll (km), the distance to the nearest large volcanic island ≥ 1000 km2 (here, Tahiti as a potential stepping-stone island) and the distance to the nearest raised atoll ≥ 15 m a.s.l. (here, Makatea or Henderson as a potential refugium during sea-level highstands). Spearman’s rank correlation, linear regression analysis and frequency diagrams were used to assess the relative influence of these factors on native species richness. No relationship was found between the species richness and the index of isolation or the distance to the nearest similar atoll. Atoll area and distance to the nearest raised atoll of Makatea explained 47.1% and 40%, respectively, of the native species richness variation observed on the remote atolls. The distance to the volcanic island of Tahiti and the coastal index explained 36.9% and 27.3% of the variation, while elevation and shoreline length explained 23.3% and 18.4% of the variation, respectively. Native species richness on the atolls surveyed increased with the increasing atoll area, elevation and shoreline length, but decreased with the increasing distance to the nearest raised atoll of Makatea and the large volcanic island of Tahiti. This supports the view that the spatial pattern of native species richness observed on the remote atolls was strongly influenced by (i) atoll area but also by (ii) the distance to the raised atoll of Makatea, and (iii) the distance to the volcanic island of Tahiti. This finding suggests that the raised atoll may be viewed as a refugium during sea-level highstands while the large volcanic island played the role of stepping-stone island, both islands influencing the dispersal of native species on remote atolls and attenuating the isolation effect in the study area.
    Mots-clés : eastern Polynesia, island biogeography, physical and spatial factors, raised atoll, refugium, remote atolls, species richness, stepping-stone-island.

  • Morel Pauline, Trappmann Daniel, Corona Christophe et Stoffel Markus« Defining sample size and sampling strategy for dendrogeomorphic rockfall reconstructions », Geomorphology, p. doi:10.1016/j.geomorph.2015.02.017. DOI : 10.1016/j.geomorph.2015.02.017.
    Résumé : Optimized sampling strategies have been recently proposed for dendrogeomorphic reconstructions of mass movements with a large spatial footprint, such as landslides, snow avalanches, and debris flows. Such guidelines have, by contrast, been largely missing for rockfalls and cannot be transposed owing to the sporadic nature of this process and the occurrence of individual rocks and boulders. Based on a data set of 314 European larch (Larix decidua Mill.) trees (i.e., 64 trees/ha), growing on an active rockfall slope, this study bridges this gap and proposes an optimized sampling strategy for the spatial and temporal reconstruction of rockfall activity. Using random extractions of trees, iterative mapping, and a stratified sampling strategy based on an arbitrary selection of trees, we investigate subsets of the full tree-ring data set to define optimal sample size and sampling design for the development of frequency maps of rockfall activity. Spatially, our results demonstrate that the sampling of only 6 representative trees per ha can be sufficient to yield a reasonable mapping of the spatial distribution of rockfall frequencies on a slope, especially if the oldest and most heavily affected individuals are included in the analysis. At the same time, however, sampling such a low number of trees risks causing significant errors especially if nonrepresentative trees are chosen for analysis. An increased number of samples therefore improves the quality of the frequency maps in this case. Temporally, we demonstrate that at least 40 trees/ha are needed to obtain reliable rockfall chronologies. These results will facilitate the design of future studies, decrease the cost–benefit ratio of dendrogeomorphic studies and thus will permit production of reliable reconstructions with reasonable temporal efforts.
    Mots-clés : Dendrogeomorphology, frequency, mass movement, Methodology, Rockfall, simulation.

  • Pouteau Robin, Meyer Jean Yves et Larrue Sébastien« Using range filling rather than prevalence of invasive plant species for management prioritisation: the case of Spathodea campanulata in the Society Islands (South Pacific) », Ecological Indicators, 54, p. 87-95. DOI : 10.1016/j.ecolind.2015.02.017.
    Résumé : Biological invasion science lacks standardised measures of invasion success that would provide effective prioritisation of invasive species and invaded areas management. Area of occupancy of invasive species is often used as proxy of their success but this metric ignores the extent to which a species fills its potential distribution. This study aims to estimate the performance of invasive tree species by computing the ratio between the compressed canopy area (CCA), assessed through remote sensing, and their potential distribution, estimated using invasive species distribution modelling. This index of ‘range filling’ (RF) has applicability to a broad set of invasive plant species in any biome. A case study is provided using the invasive African tulip tree Spathodea campanulata (Bignoniaceae) on three small tropical oceanic islands of French Polynesia (South Pacific Ocean) exhibiting different invasion levels to test for differences between CCA and RF. The results show that the RF of Spathodea campanulata varied within islands depending on elevation but not proportionally to the CCA of the species. Another key result was that the RF of the species and its CCA provided different between-island perspectives on the invasions and leaded to distinct ranking among islands to prioritise for management. Therefore, managers should disregard species’ area of occupancy as a measure of success and rather weight it with potential distribution to quantify how an invader is performing in a given environment.
    Mots-clés : Geographic information system, island ecology, management prioritisation, niche modelling, support vector machines.

  • André Marie-Françoise, Vautier Franck, Voldoire Olivier et Roussel Erwan« Accelerated stone deterioration induced by forest clearance around the Angkor temples », Science of the Total Environment, 493, p. 98-108.
    Mots-clés : cultural heritage, geomorphology and weathering.

  • Ballesteros-Cánovas Juan A., Rodríguez-Morata Clara, Garófano-Gómez Virginia, Rubiales Juan M., Sánchez-Salguero Raúl et Stoffel Markus« Unravelling past flash flood activity in a forested mountain catchment of the Spanish Central System », Journal of Hydrology, p. In press. DOI : 10.1016/j.jhydrol.2014.11.027.
    Résumé : Flash floods represent one of the most common natural hazards in mountain catchments, and are frequent in Mediterranean environments. As a result of the widespread lack of reliable data on past events, the understanding of their spatio-temporal occurrence and their climatic triggers remains rather limited. Here, we present a dendrogeomorphic reconstruction of past flash flood activity in the Arroyo de los Puentes stream (Sierra de Guadarrama, Spanish Central System). We analyze a total of 287 increment cores from 178 disturbed Scots pine trees (Pinus sylvestris L.) which yielded indications on 212 growth disturbances related to past flash flood impact. In combination with local archives, meteorological data, annual forest management records and highly-resolved terrestrial data (i.e., LiDAR data and aerial imagery), the dendrogeomorphic time series allowed dating 25 flash floods over the last three centuries, with a major event leaving an intense geomorphic footprint throughout the catchment in 1936. The analysis of meteorological records suggests that the rainfall thresholds of flash floods vary with the seasonality of events. Dated flash floods in the 20th century were primarily related with synoptic troughs owing to the arrival of air masses from north and west on the Iberian Peninsula during negative indices of the North Atlantic Oscillation. The results of this study contribute considerably to a better understanding of hazards related with hydrogeomorphic processes in central Spain in general and in the Sierra de Guadarrama National Park in particular.
    Mots-clés : Dendrogeomorphology, Flash flood, Hydrometeorological triggers, Paleohydrology, Sierra de Guadarrama, Tree ring.

  • Beauger Aude et Lair Nicole« Analyse des principales méthodes de bio-évaluation basées sur les macroinvertébrés benthiques. », Bulletin de la société linnéenne de Lyon, Bulletin hors série n° 4, p. 15-34.

  • Beauger Aude, Peiry Jean-Luc, Lair Nicole et Voldoire Olivier« Ecological characterization of natural and impacted meander cut-offs of the River Allier using benthic macroinvertebrates », Ephemera, 14 (2), p. 83-106.
    Résumé : Today, the hydrological function and biodiversity of riverine secondary channels are generally recognized and managers tend to protect and restore them. In this study we focused on different parapotamal meander cut-offs. Six sites were examined, two of them being impacted by gravel extraction or deepened for halieutic activity. In order to test whether systematic differences in communities occurred upstream and downstream of the different sites, temperature and dissolved oxygen concentration were continuously monitored, other physical and chemical data were monthly measured and benthic macroinvertebrates were sampled in two seasons. Related to the abiotic data, in each site, water exchanges occurred between the river and / or the groundwater. In the unmodified sites, those few silted up displayed the greatest biodiversity with numerous EPT (Ephemeroptera, Plecoptera and Trichoptera) while in those largely silted, the habitat homogeneity induced a low biodiversity. In the two impacted sites, the upstream modification enhanced natural silting and few EPT were present while in the site largely open to the river, water quality, diversity and EPT richness remained high.
    Mots-clés : between-class Correspondence Analysis (bCA), habitats, physical and chemical monitoring.

  • Beauger Aude, Serieyssol Karen et Peiry Jean-Luc« Diatom distribution in natural and impacted cut-off meanders of the Allier River, France », Diatom Research, 29 (2), p. 119-145. DOI : 10.1080/0269249X.2013.863224.
    Résumé : basalt and downstream – sedimentary), differ in their degrees of infill or depth. In each region, three cut-off meanders were examined; one in each region was impacted by gravel extraction (upstream deepening) and halieutic improvement (downstream deepening), whereas the others were left in their natural state having different silt accumulations either almost cut-off from the river or less silted-up and more open to the river. The sites were monitored for one year for physical and chemical characteristics. Diatom samples collected in summer 2009 were examined along with their associated biocenosis. The two catchments, differing in geology, land-use and water quality, sheltered different diatom communities. Physical and chemical differences were recorded between up- and downstream zones of each cut-off meander due to both the influence of the groundwater (buffering the water temperature among others) and the periodic inflow from the main channel (increased oxygen saturation concentration in downstream end of the cut-off meanders, except for the impacted upstream zone which contained a lot of macrophytes). In the upstream reach (except for one site), the connection with the groundwater from the surrounding catchment, which acts as a hydro-geological reservoir, might explain the highest mineralization and water hardness recorded mainly in the upstream zone of the cut-off meander, and the presence of Pseudostaurosira subsalina (Hustedt) Morales and Thalassiosira weissflogii (Grunow) Fryxell & Hasle. For the downstream reach, in addition to up- and downstream differences, other factors came into play giving rise to different communities, for example, cattle trampling in the cut-off meander leading to the presence of hypereutrophic and polysaprobic taxa or the potential local re-emergence of mineral springs associated with brackish taxa. Moreover, the up- or downstream deepening also induced differences: the extraction of sediment nearer to the river created a system in which water input from the main channel flows in through a larger opening, inducing allochthonous processes. This increased the river’s influence, creating a renewal of earlier morphological and ecological conditions, whereas the gravel extraction that modified the upstream zone increased the influence of groundwater from the surrounding catchment on this area of the site and led to water conditions independent of the main channel. Furthermore, this study has provided an important picture of the environmental variables, mechanisms and processes that drive the distribution of diatoms within the cut-off meanders along the Allier River, which can can be applied in future paleo-environmental studies.
    Mots-clés : cut-off meanders, ecology, multivariate analyses, taxa distribution, water chemistry.

  • Binder Didier, Hamon Caroline, Bellot-Gurlet Ludovic, Beyries Sylvie, Pradeau Jean-Victor, Vautier Franck et Voldoire Olivier« First Sculpted Human Face in the Western Mediterranean Early Neolithic », Cambridge Archaeological Journal, 24 (01), p. 1–17. DOI : 10.1017/S0959774314000043.
    Résumé : The development of the Neolithic way of life in the western Mediterranean during the sixth millennium cal. BC is the consequence of the spread of populations from the Near East after successive stages of cultural remodelling. Despite the clear contribution of the Near Eastern and Aegean Neolithic to the economic and technical changes that happened to the west, little is known here about their symbolic legacies, because of the scarcity of representations and ritual evidences associated to the earliest western Neolithic contexts. Excavations at the rock shelter of Pendimoun (southeastern France) yielded the first anthropomorphic stone sculpture from the western Mediterranean Neolithic (early sixth millennium cal. BC). Using both carving and painting techniques, it represents a realistic-looking human face and is a unique example within the western Mediterranean and European frameworks. After describing the shaping and colouring details of the mask, the authors here deal with its possible social significances and cultural connections.

  • Corenblit D., Steiger Johannes, Tabacchi E., González E. et Planty-Tabacchi A.-M.« Ecosystem engineers modulate exotic invasions in riparian plant communities by modifying hydrogeomorphic connectivity », River Research and Applications, 30 (1), p. 45–59.

  • Corenblit Dov, Steiger Johannes, González E., Gurnell A. M., Charrier G., Darrozes J., Dousseau J., Julien F., Lambs L., Larrue Sébastien, Roussel Erwan, Vautier Franck et Voldoire Olivier« The biogeomorphological life cycle of riparian poplar during the fluvial biogeomorphological succession: a special focus on Populus nigra L. », Earth Surface Processes and Landforms, 39 (4), p. 546–563. DOI : 10.1002/esp.3515.
    Résumé : Riverine ecosystems are recurrently rejuvenated during destructive flood events and vegetation succession starts again. Poplars (i.e. species from Populus genera) respond to hydrogeomorphological constraints, but, in turn, also influence these processes. Thus, poplar development on bare mineral substrates is not exclusively a one-way vegetative process. Reciprocal interactions and adjustments between poplar species and sediment dynamics during their life cycle lead to the emergence of biogeomorphological entities within the fluvial corridor, such as vegetated islands, benches and floodplains. Based on a review of geomorphological, biological and ecological literature, we have identified and described the co-constructing processes between riparian poplars and their fluvial environment. We have explored the possibility that the modification of the hydrogeomorphological environment exerted, in particular, by the European black poplar (Populus nigra L.), increases its fitness and thus results in positive niche construction. We focus on the fundamental phases of dispersal, recruitment and establishment until sexual maturity of P. nigra by describing the hierarchy of interactions and the pattern of feedbacks between biotic and abiotic components. We explicitly relate the biological life cycle of P. nigra to the fluvial biogeomorphic succession model by referring to the ‘biogeomorphological life cycle’ of P. nigra. Finally, we propose new research perspectives based on this theoretical framework. Copyright © 2014 John Wiley & Sons, Ltd.
    Mots-clés : abiotic-biotic feedback, biogeomorphological life cycle, biogeomorphology, engineer species, evolutionary geomorphology, fluvial biogeomorphic succession model, Salicaceae.

  • Corona Christophe, Saez Jérôme Lopez et Stoffel Markus« Defining optimal sample size, sampling design and thresholds for dendrogeomorphic landslide reconstructions », Quaternary Geochronology, 22 (22), p. 72-84. DOI : 10.1016/j.quageo.2014.02.006.
    Résumé : Trees affected by mass movements record the evidence of geomorphic disturbance in their growth-ring series, and thereby provide a precise geochronological tool for the reconstruction of past process activity. At the tree scale, identification of past mass movements was typically based on the presence of growth anomalies and focused on the presence of scars, tilted or buried trunks, as well as on apex decapitation. In terms of sampling strategy, however, clear guidelines have been largely missing. Most previous work was based either on the sampling of visibly disturbed trees irrespective of their position at the study site or on the systematic sampling of trees evenly distributed along transects. Based on a dense dataset of 323 trees growing on an active landslide body, this study aims at defining guidelines for future tree-ring sampling of landslides. Using random extractions of trees and iterative mapping, we investigate subsets of the full tree-ring sample to define optimal sampling strategy, sample depth and trees for the development of frequency maps of landslide reactivations. We demonstrate that (i) the sampling of 50-100 trees can be sufficient to obtain satisfactory results on landslide frequency without including noise to the dendrogeomorphic record; (ii) increasing growth disturbance thresholds should be adjusted to sample size and are preferable to fixed values; (iii) an even distribution of sampled trees is crucial to increase the reliability of frequency maps, even more so if the reconstruction is based on small sample sizes; and that (iv) the selection of the most frequently disturbed trees is key to reduce uncertainties in the frequency maps. The optimization of sample sizes and the adjustment of sampling strategy will not only facilitate fieldwork and render analyses and interpretation more reliable, but will also ultimately allow reconstruction of time series of past mass movements with reasonable temporal efforts and excellent cost-benefit ratios.
    Mots-clés : Dendrogeomorphology, mass movement, Sample size, Sampling design, Spatial analysis.

  • Ettinger Susanne, Manville Vern, Kruse Sarah et Paris Raphaël« GPR-derived architecture of a lahar-generated fan at Cotopaxi volcano, Ecuador », Geomorphology, 213, p. 225-239. DOI : 10.1016/j.geomorph.2014.01.013.
    Résumé : The internal geometry of volcaniclastic fans produced by aggradation during lahar events is difficult to examine in modern settings because of the frequent lack of three-dimensional exposures. This makes it challenging to (i) reconstruct the spatial and temporal evolution of such fans; and (ii) interpret observed facies stratigraphy in the context of lahar flow dynamics from proximal to distal fan reaches. This research therefore presents the results of a ground penetrating radar (GPR) survey of the Rumipamba fan at the mouth of the Burrohuaycu quebrada on the southwestern flank of Cotopaxi volcano. A survey grid consisting of 50 individual GPR profiles representing a total length of 19.4 km was constructed covering most of the 4-km2 large fan surface. All GPR profiles were collected using a PulseEKKO 100 with a 400 V transmitter. Fan sediments consist of sandy and gravelly lahar deposits, alternating with volcanic fallout including ash and pumice lapilli, at times reworked by fluvial processes. Deposits could be ground-truthed to a depth of ~3 m, whereas GPR penetration depth reaches 15 m. Data interpretation was based on classification into 15 distinct radar facies characterized by the nature of their bounding surfaces and/or internal features, cross-referenced where possible with shallow exposures. Three main facies were identified: parallel, irregular, and clinoform. Erosional contacts were distinguished from aggradational ones (vertical, channel fill, and lateral accretion). Flow parallel versus flow transverse and proximal–distal variations in deposit architecture were featured. The results of this study confirm the existence of two major channel systems in the northern and southern extremities of the fan and the more recent formation of a smaller central fan channel system. Deposit architecture is complex and facies chronologies illustrate that lahars have affected the entire survey area.
    Mots-clés : Architecture, Ecuador, Ground penetrating radar, Lahar, Sediment, Volcano.

  • González Eduardo, Cabezas Álvaro, Corenblit Dov et Steiger Johannes« Autochthonous Versus Allochthonous Organic Matter in Recent Soil C Accumulation Along a Floodplain Biogeomorphic Gradient: An Exploratory Study », Journal of Environmental Geography, 7 (1-2), p. 29–38.

  • Goubet Pierre et Darinot Fabrice« L’histoire de la tourbière de la Réserve naturelle nationale du Marais de Lavours : ce que nous révèlent les macrorestes », Bulletin hors série n°3 de la société linéenne, p. 17-29.

  • Larrue Sébastien« Cyclones influence native plant diversity on 22 remote high islands of French Polynesia and Pitcairn (eastern Polynesia). », Physical Geography, p. 497-513. DOI : 10.1080/02723646.2014.946808.
    Résumé : I examined the relative influence of eight spatial characteristics on native plant diversity in 22 volcanic high islands of eastern Polynesia. The characteristics used as potential predictors in this study included island area, highest elevation, distance to the nearest continent, distance to the nearest archipelago, distance to the nearest similar island, index of isolation, distance to the largest and highest island of Tahiti, and distance to the “cyclonic alley.” Among characteristics studied, native plant diversity (indigenous and endemic species) was primarily linked with the island area and highest elevation of the islands. Contemporary cyclones were an important predictor to explain indigenous plant diversity in the remote islands surveyed. In the study area, this result suggests that cyclones, moving from the west Pacific Ocean basin to the eastern Polynesian islands, have provided more indigenous species in the remote high islands located close to the cyclonic alley. Isolation did not appear as a significant predictor to explain native plant diversity in the high islands surveyed, possibly due to a stepping-stone-island-effect and the proximity of the cyclonic alley. These findings suggest that isolation could be tempered by a cyclonic-transport-flow-effect in the study area, thus reducing the effective distance of the remote islands from the mainland source pool for seed dispersal.
    Mots-clés : Abiotic factors, cyclones, eastern Polynesia, island biogeography, native plant diversity.

  • Larrue Sébastien, Daehler Curtis C., Vautier Franck et Bufford Jennifer L.« Forest Invasion by the African tulip tree (Spathodea campanulata) in the Hawaiian Islands: Are Seedlings Shade-Tolerant? », Pacific Science, 68 (3), p. 345-358.
    Résumé : Native to West Africa, Spathodea campanulata (African tulip tree) is frequently viewed as a shade-intolerant invader. It commonly colonizes roadsides, human-disturbed forests and abandoned agricultural land in tropical islands, where it can then become dominant in secondary forests. Some authors have suggested that the seedlings may be shade-tolerant and able to establish in closed forest, but the shade tolerance of seedlings has never been evaluated. We identified tolerated light environments of S. campanulata seedlings in wet forests in Hawaii by measuring photosynthetically active radiation (PAR) around naturally occurring seedlings (< 30 cm height) in the field. We also measured photosynthetic responses of seedlings to light under field and lab conditions, and determined seedling growth rates in sun and shade. Seedlings were found in shaded conditions in the field, and they consistently had positive net carbon gain at 50 µmol photons m-2·s-1 PAR, with an estimated mean compensation point below 10 µmol photons m-2·s-1, indicating high shade tolerance. The most frequent midday light environments of S. campanulata seedlings in the field were in the range around 50 to 200 µmol photons m-2·s-1 PAR, i.e., 2.5% to 10% of full sunlight. Among seedlings found growing in shade, minimum saturating light (Ek), determined from chlorophyll fluorescence, averaged 260 µmol photons m-2·s-1, suggesting that seedling maximum photosynthesis can occur at less than 13% of full sun. Growth rates of young seedlings in shade and sun were comparable. Widespread wind dispersal of seeds, seedling tolerance of low light, and our observations of some S. campanulata saplings establishing in rainforest without recent disturbance suggest that S. campanulata will be a persistent component of Hawaiian lowland rainforests.
    Mots-clés : Biogeography, Hawaiian Islands, Invasive species, photosynthetically active radiation (PAR), shade tolerance, Spathodea campanulata.

  • Mohammed Nabaz, Celle-Jeanton Hélène, Huneau Frederic, Le Coustumer P., Lavastre V., Bertrand G., Charrier G. et Clauzet M.L.« Isotopic and geochemical identification of main groundwater supply sources to an alluvial aquifer, the Allier River valley (France) », Journal of Hydrology, 508, p. 181-196. DOI : 10.1016/j.hydrol.2013.10.051.
    Résumé : Hydrodynamic, hydrochemical, and isotopic investigations were carried out on 18 points, including boreholes, piezometers, and surface waters, from February 2011 to August 2012, to assess groundwater quality in the unconfined shallow alluvial aquifer of the Allier River (one of the main tributary of the Loire River). The study area, located near the city of Clermont-Ferrand (France), plays an important socio-economic role as the alluvial aquifer is the major source of drinking water for about 100,000 inhabitants. The objective of the project aims at understanding the functioning of alluvial aquifers that occupy a pre-eminent position in the hydrogeologic landscape both for their economic role - production of drinking water and agricultural development - and for their ecological role. Moreover, this study also targets at determining the factors and processes controlling shallow groundwater quality and origin. The water circulates from the south, with a natural alimentation from the hills in the non-pumped part of the alluvial aquifer. In the pumping zone, this general behaviour is altered by the pumping that makes the water from the Allier River enter the system in a large proportion. Four end-members have been identified for the recharge of the alluvial groundwater: rainfall, Allier River, surrounding hills' aquifer and the southern non-pumped part of the alluvial system. Results indicate that, despite the global Ca-HCO3 water type of the groundwater, spatial variations of physico-chemical parameters do exist in the study area. Ionic concentrations increase from the Allier River towards east due either to the increase in the residence time or a mixing with groundwater coming from the aquifer's borders. Stable isotopes of the water molecule show the same results: boreholes close to the river bank are recharged by the Allier River (depleted values), while boreholes far from the river exhibit isotopic contents close to the values of hills' spring or to the southern part of the alluvial aquifer, both recharged by local precipitation. One borehole (B65) does not follow this scheme of functioning and presents values attesting of a probable sealing of the Allier River banks. Based on these results, the contribution of each end-member has been calculated and the functioning of the alluvial system determined.
    Mots-clés : Allier River, Alluvial aquifer, Groundwater, Hydrochemistry, Stable isotopes.

  • Paris Raphaël, Wassmer Patrick, Lavigne Franck, Belousov Alexander, Iskandarsyah Yann, Benbakkar Mhammed, Ontowirjo Budianto, Mazzoni Nelly et Balousova Marina« Coupling eruption and tsunami records: the Krakatau 1883 case study, Indonesia », Bulletin of Volcanology, 76, p. 814. DOI : 10.1007/s00445-014-0814-x.
    Résumé : The well-documented 1883 eruption of Krakatau volcano (Indonesia) offers an opportunity to couple the eruption’s history with the tsunami record. The aim of this paper is not to re-analyse the scenario for the 1883 eruption but to demonstrate that the study of tsunami deposits provides information for reconstructing past eruptions. Indeed, though the characteristics of volcanogenic tsunami deposits are similar to those of other tsunami deposits, they may include juvenile material (e.g. fresh pumice) or be interbedded with distal pyroclastic deposits (ash fall, surges), due to their simultaneity with the eruption. Five kinds of sedimentary and volcanic facies related to the 1883 events were identified along the coasts of Java and Sumatra: (1) bioclastic tsunami sands and (2) pumiceous tsunami sands, deposited respectively before and during the Plinian phase (26–27 August); (3) rounded pumice lapilli reworked by tsunami; (4) pumiceous ash fall deposits and (5) pyroclastic surge deposits (only in Sumatra). The stratigraphic record on the coasts of Java and Sumatra, which agrees particularly well with observations of the 1883 events, is tentatively linked to the proximal stratigraphy of the eruption.
    Mots-clés : 1883 Krakatau eruption, Indonesia, Pyroclastic fall, Pyroclastic surge, Tsunami deposits, Volcanic tsunami.

  • Poiraud Alexandre« Landslide susceptibility–certainty mapping by a multi-method approach: A case study in the Tertiary basin of Puy-en-Velay (Massif central, France) », Geomorphology, 216, p. 208-224. DOI : 10.1016/j.geomorph.2014.04.001.
    Résumé : The present study discusses the use of integrated variables along with a combination of multi-method forecasts for landslide susceptibility mapping. The study area is located in the south-eastern French Massif central, a volcanic region containing Tertiary sedimentary materials that are prone to landslides. The flowage-type landslides within the study area are very slow-moving phenomena which affect the infrastructures and human settlements. The modelling process is based on a training set of landslides (70% of total landslides) and a set of controlling factor (slope, lithology, surficial formation, the topographic wetness index, the topographic position index, distance to thalweg, and aspect). We create a composite variable (or integrated variable), corresponding to the union of geology and surficial formation, in order to avoid the conditional dependence between these two variables and to build a geotechnical variable. We use five classical modelling methods (index, weight-of-evidence, logistic regression, decision tree, and unique condition unit) with the same training set but with different architectures of input data made up of controlling factors. All the models are tested with a validation group (30% of total landslides), using the Area Under the Receiver Operating Characteristic curve (AUC) to quantify their predictive performance. We finally select a single “best” model for each method. However, these five models are all equivalent in quality, despite their differences in detail, so no single model stands out against another. Finally, we combine the five models into a unique susceptibility map with a calculation of median susceptibility class. The final AUC value of this combined map is better than that for a single model (except for Unique Condition Unit), and we can evaluate the certainty of the susceptibility class pixel by pixel. In agreement with the sparse literature on this topic, we conclude that i) integrated variables increase the performance of classical modelling processes and ii) the combination of multi-method forecasts is a pragmatic solution to the inherent problem of choosing the most suitable method for the available data and geomorphological context.
    Mots-clés : Certainty mapping, Combination forecast, Integrated variable, Landslide susceptibility mapping, multi-method, Velay.

  • Saez Jérôme Lopez, Corona Christophe, Stoffel Markus et Berger Frédéric« Assessment of forested shallow landslide movements coupling tree ring records from stems and exposed roots », Géomorphologie : Relief. Processus. Environnement, 2/2014, p. 159-174. DOI : 10.4000/geomorphologie.10616.
    Résumé : The purpose of this study is to explore and illustrate the potential of exposed roots to reconstruct larger-scale landslide activity and thus to complement tree-ring data gathered from stems to reconstruct spatio-temporal patterns of landslide reactivation. Work was undertaken in a forested area of the Davids-Bas landslide, Barcelonnette (Southeastern French Alps) and based on growth disturbances (GD) from 48 stems and on anatomical changes (decrease of cell lumina) in 20 exposed root sections of heavily affected Mountain pine (Pinus uncinata Mill. ex Mirb.) trees growing on the scarps and upon the landslide body. A total of 95 GD and 20 anatomical changes were identified in the samples pointing to 7 movements of the landslide body since AD 1977. The study demonstrates that reconstructions of landslide reactivations obtained from exposed roots samples are not significantly different from those gathered from stems, but that the inclusion of exposed roots permits realization of frequency maps in sectors which could not be documented with classic dendrogeomorphic approaches focusing on tree-ring records from stems (scars, cracks). In addition, and even more importantly, the inclusion of exposed roots allowed assessment of the geomorphic evolution of the landslide at the local scale and to detect precursor signals of major reactivations in the form of crack widening before the main movement was registered in the tree stems. In that sense, the combined approach presented in this paper can be considered as a valuable tool for land-use planners and emergency cells in charge of forecasting future events and in protecting people and their assets from the negative effects of landslides.
    Mots-clés : Dendrogeomorphology, exposed root, French Alps, landslide.

  • Stoffel Markus et Corona Christophe« Dendroecological dating of geomorphic disturbance in trees », Tree-Ring Research, 70 (1), p. 3-20. DOI : 10.3959/1536-1098-70.1.3.
    Résumé : The initial employment of tree rings in geomorphic studies was simply as a dating tool and only rarely were other environmental information and records of damage contained within the tree exploited. However, these annually resolved tree-ring records also preserve valuable archives of past geomorphic processes on timescales of decades to centuries. As many of these processes are significant natural hazards, understanding their distribution, timing and controls provides crucial information that can assist in the prediction, mitigation and defense against these hazards and their effects on society. This contribution aims at presenting a proposal on the types of growth disturbances to be included in future work focusing on geomorphic disturbance, the intensity of reactions, and on the minimum requirements needed for growth disturbances to be considered in event histories. We present possibilities and limitations of dendrogeomorphic applications in geomorphic research and propose a range of techniques and approaches that may become standard practice in the analysis and understanding of earth-surface processes and related natural hazards in the future.
    Mots-clés : Dendrogeomorphology, earth-surface process, geomorphology, hydrogeomorphology, injury, reaction wood, resin duct, tracheid, vessel, Wood anatomy.

  • Trappmann Daniel, Stoffel Markus et Corona Christophe« Achieving a more realistic assessment of rockfall hazards by coupling three-dimensional process models and field-based tree-ring data », Earth Surface Processes and Landforms, 39 (114), p. 1866–1875. DOI : 10.1002/esp.3580.
    Résumé : Sound knowledge of the spatial and temporal patterns of rockfalls is fundamental for the management of this very common hazard in mountain environments. Process-based, three-dimensional simulation models are nowadays capable of reproducing the spatial distribution of rockfall occurrences with reasonable accuracy through the simulation of numerous individual trajectories on highly-resolved digital terrain models. At the same time, however, simulation models typically fail to quantify the ‘real’ frequency of rockfalls (in terms of return intervals). The analysis of impact scars on trees, in contrast, yields real rockfall frequencies, but trees may not be present at the location of interest and rare trajectories may not necessarily be captured due to the limited age of forest stands. In this article, we demonstrate that the coupling of modeling with tree-ring techniques may overcome the limitations inherent to both approaches. Based on the analysis of 64 cells (40 m × 40 m) of a rockfall slope located above a 1631-m long road section in the Swiss Alps, we illustrate results from 488 rockfalls detected in 1260 trees. We illustrate that tree impact data cannot only be used (i) to reconstruct the real frequency of rockfalls for individual cells, but that they also serve (ii) the calibration of the rockfall model Rockyfor3D, as well as (iii) the transformation of simulated trajectories into real frequencies. Calibrated simulation results are in good agreement with real rockfall frequencies and exhibit significant differences in rockfall activity between the cells (zones) along the road section. Real frequencies, expressed as rock passages per meter road section, also enable quantification and direct comparison of the hazard potential between the zones. The contribution provides an approach for hazard zoning procedures that complements traditional methods with a quantification of rockfall frequencies in terms of return intervals through a systematic inclusion of impact records in trees.
    Mots-clés : 3D rockfall simulation models, Dendrogeomorphology, hazard assessment, rockfall frequency, Tree ring.

  • Arbellay Estelle, Stoffel Markus et Decaulne Armelle« Dating of snow avalanches by means of wound-induced vessel anomalies in sub-arctic Betula pubescens », Boreas, 42 (3), p. 568-574. DOI : 10.1111/j.1502-3885.2012.00302.x.
    Résumé : Dendrogeomorphic research has long relied on scarred trees to reconstruct the frequency of mass-movement processes. Injuries have mostly been dated macroscopically by counting the tree rings formed after wounding. Tree-ring anatomical anomalies induced by cambial injury, in contrast, have only recently been recognized as proxy records of past events. We investigated 12 sub-arctic downy birch (Betula pubescens Ehrh.) trees scarred by snow avalanches in Norway and Iceland. Earlywood vessel lumina were measured for each tree in the xylem tissue bordering the scars. Seven successive rings were examined, namely two control rings laid down prior to wounding and five rings in the wound xylem. We provide evidence that snow-avalanche-induced wounding resulted in atypically narrow earlywood vessels over at least two years. Our data demonstrate that wound-associated vessel anomalies represent tangible markers of mass-movement processes, and as such make a viable tool for reconstructing past events. Similar dendrogeomorphic studies based on tree-ring anatomy can be readily conducted with other mass-movement processes, as well as with other broad-leaved tree species. Ultimately, this new approach will foster increment coring over more invasive sampling techniques.

  • Blanckaert K., Garcia X.-F., Steiger Johannes et Uijttewaal W.« Preface Ecohydraulics : linkages between hydraulics, morphodynamics and ecological processes in rivers. », Ecohydrology, 6 (4), p. 507-510. DOI : 10.1002/eco.1414.

  • Casado Ana, Hannah David, Peiry Jean-Luc et Campo Alicia« Influence of dam-induced hydrological regulation on summer water temperature: Sauce Grande River, Argentina. », Ecohydrology, 2013 (6), p. 523–535. DOI : 10.1002/eco.1375.
    Résumé : This study quantifies for the first time the influence of flow regulation on the river thermal behaviour of an ungauged basin located in central-eastern Argentina. A 30-day data set of continuous summer hourly data was assembled for eight water temperature gauging sites deployed along the main channel upstream and downstream from the impoundment. Analysis methods include descriptive statistics of daily temperature data, classification of diurnal regimes by relative differences in the ‘shape’ and the ‘magnitude’ of the thermographs (RSMC), and quantification of the climatic sensitivity of water temperature regimes using a sensitivity index. Results revealed that temporal fluctuations in water temperatures were linked to meteorological drivers; however, spatial variability in the shape and the magnitude of the thermographs revealed the effects of the dam in regulating river thermal behaviour downstream. Water temperatures immediately below the dam were reduced notably; diurnal cycles were reduced in magnitude, delayed in timing, and revealed overall climatic insensitivity and high temporal stability in regime shape. Dam effects persisted along the 15-km stretch monitored, although declined in the downstream direction. These findings provide new scientific understanding about the river water quality and inform river management about potential shifts in summer water temperature with great implications for the diversity and lifecycles of Neotropical river fauna. The use of the RSMC and sensitivity index approaches in water temperature assessment is novel and has wider applicability for quantifying river thermal regimes and their sensitivity to drivers of change over a range of temporal and spatial scales.
    Mots-clés : flow regulation, regime shape and magnitude classification (RSMC), river water temperature, sensitivity index (SI), thermographes, ungauged basins.

  • Corenblit Dov, Julien F., Steiger Johannes, Darrozes J. et Mialet B.« High shell deposition of the invasive clam Corbicula fluminea (Müller, 1774) (Bivalvia : Corbiculidae) on alluvial bars: exploratory investigations and biogeomorphological research perspectives », Géomorphologie : Relief, Processus, Environnement, 2, p. 153-164.
    Mots-clés : Corbicula, fluminea.

  • Corona Christophe, Trappmann Daniel et Stoffel Markus« Parameterization of rockfall source areas and magnitudes with ecological recorders: When disturbances in trees serve the calibration and validation of simulation runs », Geomorphology, 202, p. 33-42. DOI : 10.1016/j.geomorph.2013.02.001.

  • Cuven Stéphanie, Paris Raphaël, Falvard Simon, Miot-Noirault Elisabeth, Benbakkar Mhammed, Schneider Jean-Luc et Billy Isabelle« High-resolution analysis of a tsunami deposit: case-study from the 1755 Lisbon tsunami in southwestern Spain », Marine Geology, 337, p. 98-111.

  • Decaulne Armelle, Sæmundsson Thorsteinn et Eggertsson Ólafur« A multi-scale resolution of snow-avalanche activity based on geomorphological investigations at Fnjóskadalur, northern Iceland », Polar Record, 49 (03), p. 220–229. DOI : 10.1017/S0032247412000605.
    Résumé : ABSTRACT The article describes investigations that highlight snow-avalanche events that have not been reported in historical records. While historical sources are most often the basis for all natural hazard and risk research, alternative methods based on geomorphic investigations are often neglected. Here, we emphasise the use of geomorphic evidence to improve our knowledge of the maximum runout distance reached by snow avalanches as well as the frequency of the events. Investigations were carried out in remote, avalanche-prone areas, where the geomorphic evidence has not been disturbed or removed. Dendrogeomorphic investigations supply annual resolved records of avalanche winters up to the age of the investigated tree stand: over 120 years in northern Iceland. The study of snow-avalanche transported debris may be used to map the extent of the potential snow-avalanche deposition zone, and offer relative dating on a secular scale; stratigraphic profiles do provide results on long timescales, but only provide relative dating. The article discusses the relevance of each method, and concludes that the combination of the three methods can improve the common risk-mitigation approach based on historical records.

  • Laraque Alain, Castellanos B., Steiger Johannes, Lopez J.L., Pandi A., Rodriguez M., Rosales J., Adèle Georges, Perez J. et Lagane C.« A comparison of the suspended and dissolved matter dynamics of two large inter-tropical rivers draining into the Atlantic Ocean : the Congo and the Orinoco », Hydrological Processes, 27 (15), p. 2153-2170. DOI : 10.1002/hyp.9776.

  • Laraque Alain, Moquet Jean-Sébastien, Alkattan Rana, Steiger Johannes, Mora Abrahan, Adèle Georges, Castellanos Bartolo, Lagane Christèle, Lopez José Luis, Perez Jesus, Rodriguez Militza et Rosales Judith« Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river: The Orinoco, Venezuela », Journal of South American Earth Sciences, 44, p. 4-17. (Hydrology, Geochemistry and Dynamic of South American Great River Systems). DOI : 10.1016/j.jsames.2012.12.011.
    Résumé : Seasonal variations of total dissolved fluxes of the lower Orinoco River were calculated taking into account four complete hydrological cycles during a five-year period (2005–2010). The modern concentrations of total dissolved solids (TDS) of the Orinoco surface waters were compared with data collected during the second half of the last century published in the literature. This comparison leads to the conclusion that chemical composition did not evolve significantly at least over the last thirty to forty years. Surface waters of the Orinoco at Ciudad Bolivar are between bicarbonated calcic and bicarbonated mixed. In comparison to mean values of concentrations of total dissolved solids (TDS) of world river surface waters (89.2 mg l−1), the Orinoco River at Ciudad Bolivar presents mainly low mineralized surface waters (2005-10: TDS 30 mg l−1). The TDS fluxes passing at this station in direction to the Atlantic Ocean between 2005 and 2010 were estimated at 30 × 106 t yr−1, i.e. 36 t km−2 yr−1. It was observed that the seasonal variations (dry season vs wet season) of total dissolved fluxes (TDS and dissolved organic carbon (DOC)) are mainly controlled by discharge variations. Two groups of elements have been defined from dilution curves and molar ratio diagrams. Ca2+, Mg2+, HCO 3 − , Cl− and Na+ mainly come from the same geographic and lithologic area, the Andes. K+ and SiO2 essentially come from the Llanos and the Guayana Shield. These findings are important for understanding fundamental geochemical processes within the Orinoco River basin, but also as a baseline study in the perspective of the development of numerous mining activities related with aluminum and steel industries; and the plans of the Venezuelan government to construct new fluvial ports on the lower Orinoco for the transport of hydrocarbons.
    Mots-clés : Hydrochemistry, Hydrology, Orinoco River, Total dissolved fluxes.

  • Mercier Denis, Cossart Etienne, Decaulne Armelle, Feuillet Thierry, Jónsson Helgi Páll et Sæmundsson Þorsteinn« The Höfðahólar rock avalanche (sturzström): Chronological constraint of paraglacial landsliding on an Icelandic hillslope », The Holocene, 23 (3), p. 432-446. DOI : 10.1177/0959683612463104.
    Résumé : The Höfðahólar rock avalanche, in the Skagafjörður area of northern Iceland, was investigated on the basis of a geomorphological analysis of its landforms and close surrounding environment. Thanks to sound chronological constraints (14C dating from birch remnants in peat areas that developed within depressions over the chaotic rock-avalanche deposit, tephrochronological sequences resulting from subsequent ash fallouts over the deposit, calibration of an age–depth model of peats and previously dated raised beaches), we define the rock-avalanche implementation with a wider timeframe between 10,200 and 7975 cal. yr BP and with a narrower frame between 9000 and 8195 ± 45 cal. yr BP. Such a well constrained timing proposes one of the most precise datings of an early-Holocene major slope failure in Iceland. This result fits well in the known chronology of the deglaciation in this area and in the prevailing Icelandic theory of a generalized phase of landsliding that occurred shortly after the deglaciation of the area. The main driver for the rock-avalanche occurrence is associated to a paraglacial origin; glacio-isostatic rebound, associated to rockwall debuttressing, is thought to be the main factor in the genesis of this Boreal major disequilibrium.
    Mots-clés : Deglaciation, early Holocene, glacio-isostatic rebound, Iceland, landsliding, paraglacial.

  • Paris Raphael, Kelfoun Karim et Giachetti Thomas« Marine conglomerate and reef megaclasts at Mauritius Island (Indian Ocean): evidences of a tsunami generated by a flank collapse of Piton de la Fournaise volcano, Réunion Island? », Science of tsunami hazards, 32 (4), p. 281-291.

  • Roussel Erwan et André Marie-Françoise« Quantitative assessment of pre- and post-restoration weathering rates of limestone Mayan temples (Uxmal, Yucatán) », Geografia Fisica e Dinamica Quaternaria, 36, p. 169-179. DOI : 10.4461/GFDQ.2013.36.14.
    Résumé : The House of Turtles is one of the Mayan buildings of the Uxmal site in Yucatan. It has been erected during the Terminal Classic Period (AD 890-915), abandoned around AD 1050, and restored between 1969 and 1972. This monument was selected to quantitatively assess the impact of contemporary restoration practices on limestone weathering. Based on archival research and multi-scale photogrammetric surveys, weathering rates were calculated for two periods, covering respectively almost 1000 years (1050-2012) and 50 years (1972-2012). Whatever the spatial scale, whatever the construction choice, post-restoration weathering rates are systematically faster than long-term rates: at the scale of the whole façade, stone recession has operated 38 times faster since restoration than on non-restored historical parts of the building (7.6 mm instead of 0.2 mm per century). This general trend is ascribed to the removal of the stucco coating that has protected limestone and delayed deterioration from the Mayan building times until the contemporary clearing and restoration operations. Another factor responsible for accelerated limestone decay is the replacement of wooden lintels by cement lintels, as indicated by the spatial distribution of deterioration hotspots on the façade and by the computed weathering rates obtained for six fine-scale windows taking into account the construction/restoration choices. This quantitative assessment leads to emphasise the need for softer, less intrusive restoration practices and conservation strategies, that should restrict the use of incompatible materials like cement and reinforced concrete, and consider stucco as a protective skin worth being maintained.
    Mots-clés : Conservation strategies, cultural heritage, Decay assessment, Limestone, Maya architecture, rock weathering, Yucatán.

  • Rovera Georges, Lopez Saez Jérôme, Corona Christophe, Stoffel Markus et Berger Frédéric« Preliminary quantification of the erosion of sandy-gravelly cliffs on the island of Porquerolles (Provence, France) through dendrogeomorphology, using exposed roots of Aleppo pine (Pinus halepensis Mill.) », Geografia Fisica e Dinamica Quaternaria, p. 10.
    Résumé : This study is a first attempt to specify the geodynamic processes leading to the erosion of detrital quaternary cliffs on the island of Porquerolles, and to quantify the rate of erosion thanks to dendrogeomorphology. The island is located in the Mediterranean Sea, off the coast of Provence (France). The method identifies the roots of Aleppo pine (Pinus halepensis Mill.) that have been unearthed by cliff retreat. The year of denudation is revealed by the net change in tracheid anatomy in tree rings, so that we can establish the retreating rates of cliffs, and assess the ratio between the distance of loosening and the number of years since denudation. 13 root samples were used to determine that the cliff retreat is due to small rockfalls, at an average rate of 2.5 cm/a. This value is compared to other rates of erosion quantified on rocky or sandy shores. A review of the method and a comparison with methods based on photogrammetry and micrometrics are proposed.
    Mots-clés : Aleppo pine, Aleppo pine., Dendrogeomorphology, Erosion rate, Littoral geodynamics, Mediterranean Sea, Quaternary cliff, Tracheid root.

  • Saez Jérôme Lopez, Corona Christophe, Berger Frédéric et Stoffel Markus« Climate change increases frequency of shallow spring landslides in the French Alps », Geology, 41 (5), p. 619-622. DOI : 10.1130/G34098.1.
    Résumé : In this contribution, past process activity is reconstructed on seven landslide bodies of the Riou Bourdoux catchment (southeastern French Alps). Based on an unusually dense data set of 3036 tree-ring series extracted from 759 conifers, we provide evidence for 61 landslide reactivations since A.D. 1898. Based on logistic regressions and threshold analyses of monthly rainfall data and temperature anomalies, we determine that the combination of snow-rich winters and positive temperature anomalies in spring (enhanced snowmelt) seems to have driven landslide reactivations in the past. Since the early 1990s, however, landslide reactivations clearly have been on the rise and thereby exhibit excessive and unprecedented rates of activity (12.5 events per 10 yr) at the scale of the Riou Bourdoux catchment. From the data, evidence exists for a shift from snowmelt-induced landslides (controlled by winter precipitation) to reactivations controlled by spring temperatures. Therefore, this contribution also adds evidence to the hypothesis that climate change (and related warmer springs) could further enhance landslide activity in the course of the 21st century.
    Mots-clés : climate change, landslides, tree-ring.

  • Schläppy Romain, Jomelli Vincent, Grancher Delphine, Stoffel Markus, Corona Christophe, Brunstein Daniel, Eckert Nicolas et Deschatres Michael« A New Tree-Ring-Based, Semi-Quantitative Approach for the Determination of Snow Avalanche Events: use of Classification Trees for Validation », Arctic, Antarctic, and Alpine Research, 45 (3), p. 383-395. DOI : 10.1657/1938-4246-45.3.383.

  • Schneuwly-Bollschweiler Michelle, Corona Christophe et Stoffel Markus« How to improve dating quality and reduce noise in tree-ring based debris-flow reconstructions », Quaternary Geochronology, 18, p. 110-118. DOI : 10.1016/j.quageo.2013.05.001.

  • Stoffel Markus, Butler David R. et Corona Christophe« Mass movements and tree rings: A guide to dendrogeomorphic field sampling and dating », Geomorphology, 200, p. 106-120. DOI : 10.1016/j.geomorph.2012.12.017.

  • Stoffel Markus, Corona Christophe, Ballesteros-Cánovas Juan Antonio et Bodoque José Maria« Dating and quantification of erosion processes based on exposed roots », Earth-Science Reviews, 123, p. 18-34. DOI : 10.1016/j.earscirev.2013.04.002.
    Résumé : Soil erosion is a key driver of land degradation and heavily affects sustainable land management in various environments worldwide. An appropriate quantification of rates of soil erosion and a localization of hotspots are therefore critical, as sediment loss has been demonstrated to have drastic consequences on soil productivity and fertility. A consistent body of evidence also exists for a causal linkage between global changes and the temporal frequency and magnitude of erosion, and thus calls for an improved understanding of dynamics and rates of soil erosion for an appropriate management of landscapes and for the planning of preventive or countermeasures. Conventional measurement techniques to infer erosion rates are limited in their temporal resolution or extent. Long-term erosion rates in larger basins have been analyzed with cosmogenic nuclides, but with lower spatial and limited temporal resolutions, thus limiting the possibility to infer micro-geomorphic and climatic controls on the timing, amount and localization of erosion. If based on exposed tree roots, rates of erosion can be inferred with up to seasonal resolution, over decades to centuries of the past and for larger surfaces with homogenous hydrological response units. Root-based erosion rates, thus, constitute a valuable alternative to empirical or physically-based approaches, especially in ungauged basins, but will be controlled by individual or a few extreme events, so that average annual rates of erosion might be highly skewed. In this contribution, we review the contribution made by this biomarker to the understanding of erosion processes and related landform evolution. We report on recent progress in root-based erosion research, illustrate possibilities, caveats and limitations of reconstructed rates, and conclude with a call for further research on various aspects of root–erosion research and for work in new geographic regions.
    Mots-clés : dendrochronology, Dendrogeomorphology, Erosion rates, Exposed roots, Target areas, Wood anatomy.

  • Touchart Laurent, Millot Camille, Maleval Véronique, Koff T., Terasmaa J., Vandel E., Vainu M., Nedjai Rachid, Bartout Pascal et Azaroual Abdelamid« Le risque de dégradation de la qualité de l'eau des lacs de la réserve naturelle de Kurtna (Estonie) : le cas de la température et de l'oxygène dissous », Riscuri si catastrofe, 13 (2), p. 49-62.
    Résumé : The Kurtna reserve (North-Eastern Estonia) includes about forty lakes of hydro-glacial origin, among which the most are kettle hole lakes. Their level and the quality of water are conditioned by aquifers, which are threatened by industrial activities (sand quarry, peat production and oil shale excavation). The paper presents results of a field campaign in March 2013, for measuring water temperature, dissolved oxygen and salinity in two ice-covered lakes (Martiska and Nõmme). Martiska is a closed lake. A large (from 0 °C to 4 °C) inverse thermal stratification takes place under the ice. The very thick anoxic layer may be caused by the cumulating effect of the ice barrier and the consumption in a rich in organic matter lake. Nõmme fits in a hydrographical chain with tributaries and an emissary. The inverse thermal stratification is disturbed by a well delimited mid-layer. Temperature, dissolved oxygen and salinity show that it is probably the fluvial water body, which has entered the lake. The hypothesis is confirmed by the study of the river plume. This inflow is rich in dissolved oxygen. We may suggest, that the lakes with an affluent are less threatened by the winter lack of oxygen than the closed lakes of the region.
    Mots-clés : banquise lacustre, dissolved oxygen, ice-covered lake, inverse stratification, oxygène dissout, stratification inverse, température de l'eau, water temperature.

  • Trappmann Daniel, Stoffel Markus et Corona Christophe« Rolling stones and tree rings: A state of research on dendrogeomorphic reconstructions of rockfall », Progress in Physical Geography, 37, p. 701-716. DOI : 10.1177/0309133313506451.
    Résumé : This progress report focuses on the contribution of tree-ring series to rockfall research and on recent development and challenges in the field. Dendrogeomorphic techniques have been used extensively since the early 2000s and several approaches have been developed to extract rockfall signals from tree-ring records of conifer trees. The reconstruction of rockfall chronologies has been hampered in the past by sample sizes that decrease as one goes back in time, as well as by a paucity of studies that include broadleaved tree species, which are in fact quite common in rockfall-prone environments. In this report, we propose a new approach considering impact probability and quantification of uncertainty in the reconstruction of rockfall time series as well as a quantitative estimate of presumably missed events. In addition, we outline new approaches and future perspectives for the inclusion of woody vegetation in hazard assessment procedures, and end with future thematic perspectives.
    Mots-clés : chronology, Dendrogeomorphology, frequency, hazard assessment, mass movement, Rockfall, simulation, Tree ring.

  • André Marie-Françoise, Voldoire Olivier, Roussel Erwan, Vautier Franck, Phalip Bruno et Hang Peou« Contrasting weathering and climate regimes in forested and cleared sandstone temples of the Angkor region », Earth Surface Processes and Landforms, 37, p. 519-532.

  • Arbellay Estelle, Corona Christophe, Stoffel Markus, Fonti Patrick et Decaulne Armelle« Defining an adequate sample of earlywood vessels for retrospective injury detection in diffuse-porous species », éd. par Ben Bond-Lamberty, PLoS ONE, 7 (6), p. e38824. DOI : 10.1371/journal.pone.0038824.
  • Astrade Laurent, Stoffel Markus, Corona Christophe et Lopez Saez Jérôme« Using tree rings to study events and morphological changes: relevance, methods, and contribution of Alpine research to dendrogeomorphology », Géomorphologie : relief, processus, environnement, 3, p. 295-316.

  • Beylich Achim A., Decaulne Armelle, Dixon John C., Lamoureux Scott F., Orwin John F., Otto Jan-Christoph, Overeem Irina, Sœmundsson Þorsteinn, Warburton Jeff et Zwolinski Zbigniew« The global Sediment Budgets in Cold Environments (SEDIBUD) Programme: Coordinated studies of sedimentary fluxes and budgets in changing cold environments », Zeitschrift f??r Geomorphologie, Supplementary Issues, 56 (1), p. 3-8. DOI : 10.1127/0372-8854/2012/S-00069.
    Résumé : Projected climate change in cold environments is expected to alter melt-season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. In addition, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depth. These effects will change surface environments in cold climate environments and alter the flfl uxes of sediments, nutrients and solutes, but the absence of data and coordinated quantitative analysis to understand the sensitivity of the surface environment are acute in cold environments. The I.A.G/A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) Programme, building on the ESF SEDIFLUX (Sedimentary Source-to-Sink-Fluxes in Cold Environments) Network, has been formed to address this key knowledge gap. Coordinated efforts are carried out to quantify, compare and model sedimentary flfl uxes and budgets in 38 selected SEDIBUD Key Test Sites (cold environment catchments) worldwide.
    Mots-clés : Cold Regions, Cold Regions Source-to-Sink Flsediment Budget, Sediment budget, Source-to-Sink Fluxes.

  • Beylich Achim A., Decaulne Armelle et Lamoureux Scott F.« Sedimentary fluxes and budgets in natural and anthropogenically modified landscapes—Effects of climate change and land-use change on geomorphic processes », Geomorphology, 167–168, p. 1. (Sedimentary fluxes and budgets in natural and anthropogenically modified landscapes – Effects of climate change and land-use change on geomorphic processes). DOI : 10.1016/j.geomorph.2012.05.027.

  • Beylich Achim A., Lamoureux Scott F. et Decaulne Armelle« The SEDIBUD (Sediment Budgets in Cold Environments) Programme: Ongoing activities and selected key tasks for the coming years », Geomorphology, 167–168, p. 2-3. (Sedimentary fluxes and budgets in natural and anthropogenically modified landscapes – Effects of climate change and land-use change on geomorphic processes). DOI : 10.1016/j.geomorph.2011.10.016.
    Résumé : Projected climate change in cold environments is expected to alter melt-season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. In addition, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. The combined effects of these changes will alter surface environments in cold climate regions and change the fluxes of sediments, nutrients and solutes, but the absence of data, coordinated process monitoring and coordinated quantitative analysis to understand the sensitivity of the Earth surface environment are acute in cold climate environments. The International Association of Geomorphologists (I.A.G./A.I.G.) SEDIBUD (Sediment Budgets in Cold Environments) Programme has been formed to address this key knowledge gap and builds on the earlier European Science Foundation (ESF) SEDIFLUX (Sedimentary Source-to-Sink-Fluxes in Cold Environments) Network. Coordinated efforts are carried out to monitor, quantify, compare and model sedimentary fluxes and possible effects of predicted climate change in currently 44 selected SEDIBUD Key Test Sites (cold climate environment catchments) worldwide.
    Mots-clés : Catchments, climate change, Cold environment, Key test site, modelling, monitoring, Sediment budgets, Sedimentary fluxes.

  • Corona Christophe, Lopez Saez Jérôme, Stoffel Markus, Bonnefoy Mylène, Richard Didier, Astrade Laurent et Berger Frédéric« How much of the real avalanche activity can be captured with tree rings? An evaluation of classic dendrogeomorphic approaches and comparison with historical archives », Cold Regions Science and Technology, 74-75, p. 31-42. DOI : 10.1016/j.coldregions.2012.01.003.

  • Corona Christophe, Lopez Saez Jérôme, Stoffel Markus, Rovera Georges, Edouard Jean-Louis et Berger Frédéric« Seven centuries of avalanche activity at Echalp (Queyras massif, southern French Alps) as inferred from tree-rings », The Holocene, 23 (2), p. 292-304.
    Résumé : The purpose of this study was to reconstruct spatio-temporal patterns of avalanche events in a forested avalanche path of the Queyras massif (Echalp avalanche path, Southeast French Alps). Analysis of past evnts was based on tree-ring series from 163 heavily affected multi-centennial larch trees (Larix decidua Mill.) near or next to the avalanche path. A total of 514 growth disturbances, such as tangential rows of traumatic resin ducts, the onset of compression wood as well as abrupt growth suppression or release, are identified in the samples indicating 38 destructive snow avalanches between 1338 and 2010. The mean return period of snow avalanches was 22 years with a 4% probability that avalanche occurs in a particular year. On a temporal plan, three maxima In snow avalanche frequency were reconstructed at the beginning of the 16th and 19th centuries and around 1850, correlating with above average winter temperatures and glacier advances. Analysis of the spatial distribution of disturbed trees contributed to the determination of four preferential patterns of avalanche events. The comparison of dendrogeomorphic data with historical records demonstrate that at least 18 events- six of were undocumented- reached the hamlet of Echalp during the last seven centuries, but no significant temporal trend was detected concerning the frequency of these extreme events.
    Mots-clés : Dendrogeomorphology, French Alps, frequency, last millennium, reconstruction, snow avalanche, tree-rings.

  • Decaulne Armelle, Eggertsson Ólafur et Sæmundsson Þorsteinn« A first dendrogeomorphologic approach of snow avalanche magnitude–frequency in Northern Iceland », Geomorphology, 167–168, p. 35-44. (Sedimentary fluxes and budgets in natural and anthropogenically modified landscapes – Effects of climate change and land-use change on geomorphic processes). DOI : 10.1016/j.geomorph.2011.11.017.
    Résumé : The paper examines the potential of dendrogeomorphic analyses to deliver a one-year resolution chronology of snow-avalanche winters in Northern Iceland, at the scale of a colluvial cone covered with European White Birch trees and shrubs (Betula pubescens Ehrh.). Reconstruction of the avalanche history is performed using tree-ring analyses. Determination of the most reliable growth disturbance (class 1 of growth eccentricity) and applying a tempering index value with threshold 10% of trees responding in the same year and at least two trees affected, avalanche-activity years are highlighted, resulting in 52 avalanche winters. Amongst those, 5 winters have activity index over 40%, indicating major years. Calculation of frequency of similar growth disturbances at each tree provides a return period ranging from 4.2 to 19 years. Inferred spatial extent of snow-avalanche events induces flow-like snow avalanches with limited extent around the tree-less parts of the cone with a return period under 6 years; the cone is totally covered and the distal tree-limit over-passed with a return period of 15–20 years.
    Mots-clés : Dendrogeomorphology, European White Birch (Betula pubescens Ehrh.), Iceland, snow avalanche.

  • Feuillet Thierry, Mercier Denis, Decaulne Armelle et Cossart Etienne« Classification of sorted patterned ground areas based on their environmental characteristics (Skagafjörður, Northern Iceland) », Geomorphology, 139–140, p. 577-587. DOI : 10.1016/j.geomorph.2011.12.022.
    Résumé : A multivariate statistical method (factor analysis of mixed data and hierarchical classification) was used to classify the environmental settings where sorted patterned ground develops in a wet oceanic periglacial area (Skagafjörður, Northern Iceland). A total of 750 periglacial features, distributed over 75 sites, were studied. Nine explanatory variables were assessed by fieldwork and using a digital elevation model, the variables were subdivided into three groups (latitude, topography and soil characteristics) and then integrated into a geographical information system. Furthermore, a correlation between the environmental variables and an intrinsic variable (patterned ground mesh diameter) was determined by a bivariate test. The results show that sorted patterned ground are spread over three homogenous areas, mostly differentiated by altitude, insolation, grain size characteristics and type of drift. In addition, feature diameters differ significantly from one group to another. Finally, it appears that patterned ground diameters are positively correlated with (i) the proportion of clay to medium silt content (r = 0.35), (ii) altitude (r = 0.51), and especially with (iii) clast length (r = 0.97). This strong relationship with clast length is observed in each homogenous patterned ground area at both site and feature scales.
    Mots-clés : Circles, Factor analysis, Periglacial geomorphology, Polygons, Subarctic.

  • Fournier Jérôme, Etienne Samuel et Le Cam Jean-Benoit« Inter- and intraspeci c variability in the chemical composition of the mineral phase of cements from several tube-building polychaetes », Geobios, 43 (2), p. 191-200.

  • Gurnell Angela M., Bertoldi Walter et Corenblit Dov Jean-francois« Changing river channels: the roles of hydrological processes, plants and pioneer fluvial landforms in humid temperate, mixed load, gravel bed rivers. », Earth-Science Reviews, 111, p. 129-141. DOI : 10.1016/j.earscirev.2011.11.005.
    Résumé : The fluvial riparian and aquatic patch mosaic varies along rivers according to geomorphological setting, hydrological regime, sediment supply and surface–groundwater connectivity. This relation between physical processes and plants is not unidirectional. Once established, riparian and aquatic plants frequently act as physical ecosystem engineers by trapping and stabilising sediments, organic matter and the propagules of other plant species, modifying the local sedimentary and morphological environment by driving the development of landforms and associated habitats, and so facilitating the rapid establishment of other plants that can in turn reinforce the development of landforms such as river banks, vegetated islands and floodplains. This paper reviews knowledge on the hydrogeomorphological significance of riparian and aquatic vegetation with a particular emphasis on humid temperate, mixed load, gravel bed, floodplain rivers. First, we investigate how vegetation dynamics across river margins are governed by hydrological processes that can both promote riparian vegetation growth and disturb and destroy riparian and aquatic vegetation. We show, with some simple numerical modeling, that different combinations of moisture supply and flow disturbance have the potential to generate many different responses in the lateral distribution of vegetation biomass along river corridors. Second, building on the varied lateral biomass distributions that are primarily dictated by hydrological processes, we review research evaluating characteristic vegetation-mediated landform development. We investigate aquatic and riparian plants acting as physical ecosystem engineers by creating and modifying habitats in river systems with sufficient suspended sediment supply for habitat or landform building. These plants have a crucial impact on sediment stabilisation and pioneer landform building along the interface between plant (resistance) dominated and fluvial-disturbance (force) dominated zones of the river corridor. We present some examples of vegetation-mediated landforms along rivers with strongly contrasting hydrological regimes and thus lateral distributions of vegetation. Lastly, we present a conceptual synthetic model that links the development of pioneer landforms by engineering plants with river morphology and morphodynamics in humid temperate, mixed load, gravel bed, floodplain rivers. Drawing on four example rivers, we show how different plants and pioneer landforms act at the interface between the plant dominated and fluvial-disturbance dominated zones of the river corridor as river energy and vegetation colonisation and growth change.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus et Berger Frédéric« High-resolution fingerprints of past landsliding and spatially explicit, probabilistic assessment of future reactivations: Aiguettes landslide, Southeastern French Alps », Tectonophysics. DOI : 10.1016/j.tecto.2012.04.020.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Schoeneich Philippe et Berger Frédéric« Probability maps of landslide reactivation derived from tree-ring records: Pra Bellon landslide, southern French Alps », Geomorphology, 138 (1), p. 189-202. DOI : 10.1016/j.geomorph.2011.08.034.

  • Poiraud Alexandre« Knickpoints from watershed scale to hillslope scale: a key to landslide control and geomorphological resilience Knickpoints and landslide patterns », Zeitschrift fur Geomorphologie Supplement Band, 56 (4), p. 19-35. DOI : 10.1127/0372-8854/2012/S-00078.
    Résumé : The analysis of different geomorphic contexts in the Puy-en-Velay Tertiary basin (Massif central, France) reveals the importance of knickpoints in active landslide patterns at different spatial scales. At the watershed scale (mesoscale), landslides are essentially located downstream of knickpoints as a result of headward erosion dynamics driven by the incision of the river Loire and local base level lowering. At the hillslope scale, knickpoints illustrate morphostructural conditions and landslide dynamics, dependent on the elevation of the crystalline basement relative to the lowering of the hydrographic network. Hillslopes currently connected with the hydrographic network are still active, while disconnected hillslopes are fossilised. Finally, knickpoints can be considered as being strong discontinuities separating different geomorphologic units. The latter form as a result of variable adjustment tendencies to the base level (present or old) and consequently different hillslope dynamics. In short, knickpoints mark a limit between areas of different different hillslope dynamics. In short, knickpoints mark a limit between areas of different geomorphologic sensitivity and differ in their capacity for resilience.
    Mots-clés : $\bullet$, geomorphologic, knickpoint, landslide, resilience, Velay.

  • Saemundsson Thorsteinn, Arnalds Olafur, Kneisel Christof, Jonsson Helgi Pall et Decaulne Armelle« The Orravatnsrustir palsa site in Central Iceland—Palsas in an aeolian sedimentation environment », Geomorphology, 167–168, p. 13-20. (Sedimentary fluxes and budgets in natural and anthropogenically modified landscapes – Effects of climate change and land-use change on geomorphic processes). DOI : 10.1016/j.geomorph.2012.03.014.
    Résumé : The Orravatnsrustir palsa site, located north of the Hofsjokull glacier in Central Iceland, has well developed palsas located in a valley-like depression at 710–715 m a.s.l. and stands in remarkable contrast to the surrounding desert-like highland plateau. The purpose of this paper is to give an overview of the Orravatnsrustir palsa site, geographic distribution and geomorphic statistics related to size and permafrost thicknesses of the palsas, including recent changes. Icelandic palsas exhibit characteristics of both organic palsas and lithalsa (frozen mineral soil). They are subjected to intense aeolian deposition of volcanic materials. The palsas are often 40–200 cm high, with a 40–80 cm thick active layer and permafrost reaching more than 5 m depth. Measurements of the size of the palsas and the thickness of the active layer which started in 2001 indicate that their size is decreasing and the thickness of the active layer is increasing. These results are in agreement with the general warming trend which has occurred in Iceland during the last decade.
    Mots-clés : Andosol, Global warming trend, Iceland, Palsas, Permafrost.

  • Steiger Johannes et Corenblit D.« The emergence of an 'evolutionary geomorphology'? », Central European Journal of Geosciences, 4 (3), p. 376-382.

  • Thierry Feuillet, Mercier Denis, Decaulne Armelle et Cossart Etienne« Classification of sorted patterned ground areas based on their environmental characteristics (Skagafjörḥur, Northern Iceland) », Geomorphology, 139-140, p. 577-587. DOI : 10.1016/j.geomorph. 2011.12.022.
    Résumé : A multivariate statistical method (factor analysis of mixed data and hierarchical classification) was used to classify the environmental settings where sorted patterned ground develops in a wet oceanic periglacial area (Skagafjörður, Northern Iceland). A total of 750 periglacial features, distributed over 75 sites, were studied. Nine explanatory variables were assessed by fieldwork and using a digital elevation model, the variables were subdivided into three groups (latitude, topography and soil characteristics) and then integrated into a geographical information system. Furthermore, a correlation between the environmental variables and an intrinsic variable (patterned ground mesh diameter) was determined by a bivariate test. The results show that sorted patterned ground are spread over three homogenous areas, mostly differentiated by altitude, insolation, grain size characteristics and type of drift. In addition, feature diameters differ significantly from one group to another. Finally, it appears that patterned ground diameters are positively correlated with (i) the proportion of clay to medium silt content (r = 0.35), (ii) altitude (r = 0.51), and especially with (iii) clast length (r = 0.97). This strong relationship with clast length is observed in each homogenous patterned ground area at both site and feature scales.
    Mots-clés : * Circles, * Factor analysis, * Periglacial geomorphology, * Polygons, * Subarctic.

  • André Marie-Françoise, Phalip Bruno, Voldoire Olivier, Vautier Franck, Géraud Yves, Benbakkar Mhammed, Constantin Christophe, Huber Fabienne et Morvan Gilles« Weathering of sandstone lotus petals at the Angkor site: a 1,000-year stone durability trial », Environmental Earth Sciences, 63, p. 1723-1739. DOI : 10.1007/s12665-010-0734-9.
    Mots-clés : Angkor temples, Cambodia, Chemical weathering, Mechanical weathering, Sandstone durability, Stone properties.

  • Beylich A.A., Lamoureux S.F. et Decaulne Armelle« Developing frameworks for studies on sedimentary fluxes and budgets in changing cold environments », Quaestiones Geographicae, 30, p. 5-18.
    Mots-clés : climate change, cold environments, contemporary sediment fluxes and budgets, coordinated data collection and exchange, inter-site comparisons, monitoring.

  • Carracedo Juan Carlos, Guillou Hervé, Nomade S., Rodríguez Badiola Eduardo, José Pérez Torrado Francisco, Rodriguez Gonzales Alejandro, Paris Raphael, Troll R., Valentin, Wiesmaier Sebastian, Delcamp Audray et Fernández Turiel J.L.« Evolution of ocean island rifts: the northeast rift-zone of Tenerife, Canary Islands », Geological Society of America Bulletin, 123, p. 532-584.

  • Chenet Marie, Roussel Erwan, Jomelli Vincent, Grancher Delphine et Cooley Daniel« A response to the commentary of M. Dąbski about the paper ‛Asynchronous Little Ice Age glacial maximum extent in southeast Iceland’ (Geomorphology (2010), 114, 253–260) », Geomorphology, 128 (1-2), p. 103-104. DOI : 10.1016/j.geomorph.2010.12.024.
    Résumé : In a commentary about the paper ‛Asynchronous Little Ice Age glacial maximum extent in southeast Iceland’ (Geomorphology 114 (2010) 253-260), M. Dąbski questioned the validity of the generalized extreme value method and the Bayesian approach in lichenometric dating of the outermost LIA Fláajökull moraines in SE Iceland. This paper responds to these criticisms by explaining the relevance of the method applied and the relevance of the dates obtained.
    Mots-clés : Bayesian approach, Fláajökull, GEV method, Iceland, Lichenometry.

  • Corenblit Dov, Baas Andreas C.W., Bornette Gudrun, Darrozes José, Delmotte Sebastien, Francis Robert A., Gurnell Angela M., Julien Frédéric, Naiman R.J. et Steiger Johannes« Feedbacks between geomorphology and biota controlling Earth surface processes and landforms: A review of foundation concepts and current understandings », Earth-Science Reviews, 106 (3-4), p. 307-331. DOI : 10.1016/j.earscirev.2011.03.002.
    Résumé : This review article presents recent advances in the field of biogeomorphology related to the reciprocal coupling between Earth surface processes and landforms, and ecological and evolutionary processes. The aim is to present to the Earth Science community ecological and evolutionary concepts and associated recent conceptual developments for linking geomorphology and biota. The novelty of the proposed perspective is that (1) in the presence of geomorphologic-engineer species, which modify sediment and landform dynamics, natural selection operating at the scale of organisms may have consequences for the physical components of ecosystems, and particularly Earth surface processes and landforms; and (2) in return, these modifications of geomorphologic processes and landforms often feed back to the ecological characteristics of the ecosystem (structure and function) and thus to biological characteristics of engineer species and/or other species (adaptation and speciation). The main foundation concepts from ecology and evolutionary biology which have led only recently to an improved conception of landform dynamics in geomorphology are reviewed and discussed. The biogeomorphologic macroevolutionary insights proposed explicitly integrate geomorphologic niche-dimensions and processes within an ecosystem framework and reflect current theories of eco- evolutionary and ecological processes. Collectively, these lead to the definition of an integrated model describing the overall functioning of biogeomorphologic systems over ecological and evolutionary timescales.
    Mots-clés : biogeomorphologic feedback, biogeomorphologic succession, eco-evolutionary dynamics, ecosystem engineers, landforms, niche construction.

  • Corona Christophe, Edouard Jean-Louis, Guibal Frederic, Guiot Joel, Bernard Sylvain, Thomas Andre et Denelle Nicole« Long-term summer (AD751-2008) temperature fluctuation in the French Alps based on tree-ring data », Boreas, 40 (2), p. 351-366. DOI : 10.1111/j.1502-3885.2010.00185.x.
  • Corona Christophe, Edouard Jean-Louis, Guibal Frédéric, Lambert Georges-Noel, Py Vanessa, Guiot Joel et Thomas André« Last Millenium summer temperature variations in Briançonnais (French Alps) based on a composite tree-ring larch chronology », Scientia artis, 7, p. 26-41.

  • Corona Christophe, Lopez Saez Jérôme, Rovéra Georges, Stoffel Markus, Astrade Laurent et Berger Frédéric« High resolution, quantitative reconstruction of erosion rates based on anatomical changes in exposed roots at Draix, Alpes de Haute-Provence — critical review of existing approaches and independent quality control of results », Geomorphology, 125 (3), p. 433-444. DOI : 10.1016/j.geomorph.2010.10.030.

  • Corona Christophe, Lopez Saez Jérôme, Rovéra Georges, Astrade Laurent, Stoffel Markus et Berger Frédéric« Validation d’une méthode de quantification des vitesses d’érosion sur marnes par dendrogéomorphologie (Draix, Alpes de Haute-Provence) », Géomorphologie : relief, processus, environnement, 1/2011, p. 83-94. DOI : 10.4000/geomorphologie.9254.

  • Desroy N., Dubois S. F., Fournier J., Ricquiers L., Le Mao P., Guerin L., Gerla D., Rougerie M. et Legendre A.« The conservation status of Sabellaria alveolata (L.) (Polychaeta: Sabellariidae) reefs in the Bay of Mont-Saint-Michel », Aquatic Conservation: Marine and Freshwater Ecosystems, 21 (5), p. 462-471. DOI : 10.1002/aqc.1206.
    Résumé : * Reefs built by the annelid worm Sabellaria alveolata in the Bay of Mont-Saint-Michel (France) are the most extensive intertidal biogenic structures within Europe. Before and after mussel farming extensions, a study designed to provide a biological health index of the Sainte-Anne reef (223 ha) was carried in 2001 and 2007 to serve as an easy-to-use management tool and to ensure endangered reef portions were properly targeted and protected. * Coupled physical and biological parameters were included in a spatial Health Status Index (HI). A spatial and temporal mapping survey of the HI showed a continuous deterioration of the reef's state of health, particularly in its central part. This degradation correlates with the colonization of the Pacific oyster Crassostrea gigas and with increasing silt deposits on the reef. * A combination of several factors is likely to explain such rapid reef deterioration: (1) an increase in trophic competition between cultivated and wild suspension-feeders that is detrimental to the annelids; (2) a modification in the hydrodynamics and consequently in sedimentary patterns leading to an increase in silt deposition; and most importantly (3) an increase in recreational harvesting of oysters and associated reef trampling, resulting in reef fragmentation. * Understanding the parameters that influence the reef dynamics is necessary in order to help efficient and effective management and policy focusing on the conservation status of large biogenic structures. Copyright © 2011 John Wiley & Sons, Ltd.
    Mots-clés : biogenic reef, biological indicator, health status, recreational fishing activities, Sabellaria alveolata, shellfish farming.

  • Etienne Samuel, Buckley Mark, Paris Raphaël, Nandasena Aruna K., Clark Kate, Strotz Luke, Chagué-Goff Catherine, Goff James et Richmond Bruce« The use of boulders for characterising past tsunamis: Lessons from the 2004 Indian Ocean and 2009 South Pacific tsunamis », Earth-Science Reviews, 107 (1–2), p. 76-90. (The 2009 South Pacific tsunami). DOI : 10.1016/j.earscirev.2010.12.006.
    Résumé : Tsunamis are high energy events capable of transporting extremely heavy loads including boulders. We compare boulder deposits created by two modern tsunami events, the 2004 Indian Ocean and the 2009 South Pacific tsunamis, where the boulder sources were in similar topographic settings, and for which we have accurate data on the wave characteristics. Boulder distribution, preferential orientation and numerical simulation of boulder transport are discussed. A comparison between the impacts of the South Pacific and Indian Ocean tsunamis shows similar characteristics, such as limited landward extent and the absence of landward fining. Differences between the results from modelling and field data are most probably caused by variables such as coastal plain roughness (buildings, trees), microtopography, particle shape, and boulder collision during transport that are summarised as coefficients in the mathematical models. Characterising modern events through coarse sediment deposits provides valuable information to help identify and interpret palaeo-tsunami imprints on coastal landscapes.
    Mots-clés : boulder deposit, geomorphology, Indonesia, Samoa, transport simulation, Tsunami.

  • Giachetti Thomas, Burgisser Alain, Arbaret Laurent, Druitt T. et Kelfoun Karim« Quantitative textural analysis of Vulcanian pyroclasts (Montserrat) using multi-scale X-ray computed microtomography: comparison with results from 2D image analysis », Bulletin of Volcanology / Bull Volcanic Eruptions, 73 (9), p. 1295-1309. DOI : 10.1007/s00445-011-0472-1.
    Résumé : X-ray computed microtomography (μCT) was carried out on four pyroclasts from the 1997 Vulcanian explosions of Soufrière Hills Volcano, Montserrat. Three-dimensional data from multiple image stacks with different spatial resolutions (0.37, 4-8, and 17.4 μm px−1) were combined to generate size distributions of vesicles, inter-vesicle throats, crystals, and Fe-Ti oxides over a 3.4-860-μm size range, and to compare the results with those obtained by 2D image analysis on the same samples. Qualitative textural observations are in good agreement with those made in 2D, but μCT provides better resolution of textural features and spatial relationships. Calculation of size distributions requires automated decoalescence of the connected vesicle network. Problems related to this process, in part due to the high porosity of pumice, result in potential artefacts in the calculated size distributions, which are discussed in detail. The main modes of the 3D vesicle volume distributions are systematically shifted to larger sizes compared with those of the 2D distributions. Sample total vesicularities obtained in 3D are within 13 vol.% of those found in 2D, and within 10 vol.% of those measured by He-pycnometry. Total number densities of vesicles and Fe-Ti oxides from the two methods are consistent only to the first order, 3D values ranging from 37% to 309% of those in 2D. Vesicle coalescence, investigated by examining inter-vesicle throat size distributions, occurred in all pyroclasts between neighbouring vesicles of many sizes. The larger the vesicle, the more connected it is.
    Mots-clés : Coalescence, Montserrat, Soufrière Hills Volcano, Vesicle number density, Vesicle size distribution, Vulcanian explosions, X-ray computed microtomography.

  • Giachetti Thomas, Paris Raphael, Kelfoun Karim et José Pérez Torrado Francisco« Numerical modelling of the tsunami triggered by the Güìmar debris avalanche, Tenerife (Canary Islands): comparison with field-based data », Marine Geology, 284, p. 189-202.

  • Girard François, Vennetier Michel, Guibal Frédéric, Corona Christophe, Ouarmim Samira et Herrero Asier« Pinus halepensis Mill. crown development and fruiting declined with repeated drought in Mediterranean France », European Journal of Forest Research, 131 (4), p. 919-931. DOI : 10.1007/s10342-011-0565-6.

  • Godet Laurent, Fournier Jérôme, Jaffré Mikaël et Desroy Nicolas« Influence of stability and fragmentation of a worm-reef on benthic macrofauna », Estuarine, Coastal and Shelf Science, 92 (3), p. 472-479. DOI : 10.1016/j.ecss.2011.02.003.
    Résumé : In coastal areas, reef-builder worms often are bio-engineers by structuring their physical and biological environment. Many studies showed that this engineering role is determined by the densities of the engineer species itself, the highest densities approximately corresponding to the most stable areas from a sedimentological point of view, and hosting the richest and the most diverse benthic fauna. Here, we tested the potential influence of the spatio-temporal dynamics and the spatial fragmentation of one of the largest European intertidal reefs generated by the marine worm Lanice conchilega (Pallas, 1766) (Annelida, Polychaeta) on the associated benthic macrofauna. We demonstrated that the worm densities do have a significant positive role on the abundance, biomass, species richness and species diversity of the benthic macrofauna and that the reef stability also significantly influences the biomass and species diversity. Moreover, the reef fragmentation has significant negative effects on the abundance, biomass and species richness. In addition to L. conchilega densities, the stability and the spatial fragmentation of the reef also significantly structure the associated benthic assemblages. This study demonstrates the interest of “benthoscape ecology” in understanding the role played by marine engineer species from a spatial point of view.
    Mots-clés : Bay of the Mont-Saint-Michel, fragmentation, Reefs, stability, tidal flats, zoobenthos.

  • Le Cam Jean-Benoit, Fournier Jérôme, Etienne Samuel et Couden Jérôme« The strength of biogenic sand reefs: Visco-elastic behaviour of cement secreted by the tube building polychaete Sabellaria alveolata, Linnaeus, 1767 », Estuarine Coastal and Shelf Science, 91 (2), p. 333-339. DOI : 10.1016/j.ecss.2010.10.036.
    Résumé : Mechanical properties of the biomineralised cement from tube-building marine worms are poorly known. Secreted from an organ connected to the polychaetes specialised glands, the cement glues sand grains and calcareous shell fragments of a given size and, on a larger scale, ensures the resistance of the reef to waves. In this study, three kinds of mechanical tests were performed with worm tubes to establish the nature of the cement behaviour. Results obtained show that cement behaves like a visco-elastic material. This property allows the tubes to dissipate the mechanical energy from the waves to which they are subject and to reduce the mechanical stress transmitted inside the tubes to the polychaetes. Comparison of “fresh” and “dry” cements highlights that the visco-elastic behaviour of the cement is maintained after five years. The viscosity of the cement is therefore not related to moisture but to its chemical composition. More generally, these results offer a better understanding of the role of cement on worm reefs strength and their persistence in the geological record.
    Mots-clés : biogenic reef, biogeomorphology, mechanical behaviour, Sabellaria alveolata, visco-elasticity.

  • Leone Frédéric, Lavigne Franck, Paris Raphael et Denain Jean-Charles« A spatial analysis of the December 26th, 2004 tsunami-induced damages: lessons learned for a better risk assessment integrating buildings vulnerability. », Applied Geography, 31 (1), p. 363-375.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Astrade Laurent, Berger Frédéric et Malet Jean-Philippe« Dendrogeomorphic reconstruction of past landslide reactivation with seasonal precision: the Bois Noir landslide, southeast French Alps », Landslides, p. 189-203. DOI : 10.1007/s10346-011-0284-6.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Gotteland A., Berger Frédéric et Liébault F.« Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data », Natural Hazards and Earth System Science, 11, p. 1247-1257. DOI : 10.5194/nhess-11-1247-2011.

  • Lopez Saez Jérôme, Corona Christophe, Stoffel Markus, Rovéra Georges, Astrade Laurent et Berger Frédéric« Mapping of erosion rates in marly badlands based on a coupling of anatomical changes in exposed roots with slope maps derived from LiDAR data », Earth Surface Processes and Landforms, 36 (9), p. 1162-1171. DOI : 10.1002/esp.2141.

  • Nandasena N.A.K., Paris Raphael et Tanaka Norio« Reassessment of hydrodynamic equations to initiate boulder transport by high energy events (storms, tsunamis) », Marine Geology, 281, p. 70-84.

  • Nandasena Nak, Paris Raphael et Tanaka Norio« Numerical assessment of boulder transport by 2004 Indian Ocean tsunami in Lhok Nga, West Banda Aceh (Sumatra, Indonesia) », Computers and Geosciences, 37, p. 1391-1399.

  • Paris Raphael, Naylor Larissa et Stephenson Wayne« Boulders as a signature of storms on rock coasts », Marine Geology, 283, p. 1-11.

  • Rovera Georges, Corona Christophe et Lopez Saez Jérôme« High resolution, quantitative reconstruction of erosion rates based on anatomical changes in exposed roots at Draix, Alpes de Haute-Provence - critical review of existing approaches and independent quality control of results », Geomorphology, 125, p. 433-444.
    Résumé : Extensive areas of French Alps are underlain by Jurassic black marls. Wherever these "terres noires" crop out they become subject to intense erosion, causing major sedimentation in regional reservoirs and river systems. In the badlands near Draix (Alpes de Haute-Provence, France), measured sediment rates were obtained at the plot scale by surface elevation change-based methods and at the catchment scale by monitoring sedimentation in dams. In this study, we use a dendrogeomorphic approach based on anatomical changes in exposed roots of Pinus sylvestris L. to accurately quantify continuous denudation rates. A total of 123 cross sections (75 from buried and 48 from exposed roots of 23 trees) were sampled in the Moulin basin. The size and position of roots at the time of exposure was determined via anatomical variations in the annual growth rings of roots. In cross sections of buried roots, a sharp reduction of earlywood tracheid lumen area - a growth signature which has traditionally been used to determine the moment of root denudation - was observed as soon as erosion reduced soil cover to < 3 cm. As a consequence, estimates of eroded soil thickness had to be adjusted to take account of this bias. Bias-adjusted, averaged, medium term erosion rates derived from exposed roots vary between 6 and 7 mm y-1 at Moulin basin depending on the importance accorded to the uplift of roots after exposure. values are significantly correlated to slope angle and match with erosion rates derived from monitored iron stakes (5.7 mm y-1) or measurements of sediment yield in retention dams. (4.7 mm y-1) at the outlet of the Moulin basin. Besides demonstrating that the interpretation of anatomical signatures in tree roots to erosion have to be revised, this paper also shows that dendrogeomorphic analyses of roots are indeed a powerful tool for the quantification of minimal rates of soil erosion in environments where measurements of past activity are not available.
    Mots-clés : badlands, black marls, Dendrogeomorphology, earlywood tracheids, Erosion rates, Exposed roots, Pinus sylvestris L, Pinus sylvestris L..

  • Rovera Georges, Corona Christophe et Lopez Saez Jérôme« Quantification des vitesses d'érosion par dendrogéomorphologie : utilisation des racines déchaussées dans les badlands marneux des bassins expérimentaux de Draix (Alpes de Haute-Provence) », Géomorphologie : Relief. Processus. Environnement, 1, p. 83-94.
    Résumé : Les marnes noires du Jurassique couvrent de vastes surfaces dans les Alpes françaises du Sud. Partout où elles affleurent, elles sont sujettes à une érosion intense à l'origine de problèmes de sédimentation dans les cours d'eau et d'envasement dans les réservoirs hydro-électriques. Dans les badlands de Draix (Alpes de Haute-Provence), les vitesses d'érosion obtenues par différentes méthodes de mesure atteignent 5 à 10 mm/a. Dans cette étude, les mesures d'érosion quantifiées au moyen d'une approche dendrogéomorphologique sont validées par comparaison avec celles issues du suivi micrométrique d'un réseau de 47 tiges métalliques. Trente-neuf racines de Pinus sylvestris L. déchaussées ont été échantillonnées dans le bassin-versant du Moulin (8 ha) et l'impact de la dénudation sur les variations anatomiques des cernes annuels de croissance a été mesuré. L'année de déchaussement a pu être déterminée via l'étude de la diminution très rapide, de l'ordre de 60%, de la surface du lumen des trachéides. Les vitesses d'érosion mesurées au moyen de la dendrogéomorphologie atteignent en moyenne 5 mm/an et montrent une corrélation significative [r²(d)=0,39] mais non exclusive avec la pente locale. Elles concordent avec celles obtenues à partir de mesures micrométriques (5,7 mm/a en moyenne) et par cubages réalisés à l'exutoire du bassin-versant (4,7 mm/a). Dés lors, cette approche offre des perspectives particulièrement intéressantes pour quantifier et spatialiser rapidement les vitesses d'érosion moyennes sur plusieurs décennies, dans des bassins versants non instrumentés.
    Mots-clés : badlands, dendrogéomorphologie, micrométrie, racines, vitesse d'érosion.

  • Saulnier Mélanie, Edouard Jean-Louis, Corona Christophe et Guibal Frédéric« Climate/growth relationships in a Pinus cembra high-elevation network in the Southern French Alps », Annals of Forest Science, 68 (1), p. 189-200. DOI : 10.1007/s13595-011-0020-3.

  • André Marie-Françoise et Phalip Bruno« Evaluating rates of stone recession on Mediaeval monuments : Some thoughts and methodological perspectives. », Cadernos do Laboratorio Xeolóxico de Laxe, 35, p. 13-40.
    Mots-clés : cultural heritage, geomorphology and weathering.

  • Beylich Achim A., Lamoureux Scott F., Decaulne Armelle, Dixon John C., Orwin John F., Otto Jan-Christoph, Overeem Irina, Sæmundsson Þorsteinn, Warburton Jeff et Zwolinski Zbigniew« Sedimentary Fluxes and Budgets in Changing Cold Environments: The Global Iag/Aig Sediment Budgets in Cold Environments (sedibud) Programme », Geografiska Annaler: Series A, Physical Geography, 92 (2), p. 151-153. DOI : 10.1111/j.1468-0459.2010.00386.x.

  • Chenet Marie, Roussel Erwan, Jomelli Vincent et Grancher Delphine« Asynchronous Little Ice Age glacial maximum extent in southeast Iceland », Geomorphology, 114 (3), p. 253-260.
    Résumé : The Little Ice Age (LIA) maximum glacial extent of 13 glaciers located in SE Iceland was dated by lichenometry to check for intraregional variations. Different lichenometric approaches were applied to date maximum LIA moraines, and they all showed high variability between glaciers. According to the Extreme Value Theory and Bayesian approach, LIA advances in the region occurred in or around A.D. 1740–1760, A.D. 1810–1820 and A.D. 1840–1880 with confidence intervals of between 8 and 21 years. The dates were correlated with geomorphic characteristics of glacier tongues: hypsometric and slope parameters can be considered as determining factors in the variability of glacier timing during the LIA, as previously observed in Norway and in the Alps. In terms of timing, results obtained in SE Iceland were similar to those obtained for other glacier regions around the North Atlantic.
    Mots-clés : Dating, Glacier, Iceland, Lichenometry, Little Ice Age.

  • Conway S. J., Decaulne A., Balme M. R., Murray J. B. et Towner M. C.« A new approach to estimating hazard posed by debris flows in the Westfjords of Iceland », Geomorphology, 114 (4), p. 556-572. DOI : 10.1016/j.geomorph.2009.08.015.
    Résumé : The aim of this study is to improve the assessment of hazard posed by debris flows to the people and settlements of Northwest Iceland by studying very recent examples from above the town of Ísafjörður and other nearby localities. Debris flows are a recognised hazard in the region: above Ísafjörður, they occur with particularly high frequency and have appreciable volumes (up to 14 000 m3). We have used airborne laser altimeter (LiDAR) and differential Global Positioning System (GPS) data to produce isopach maps of flows that occurred in 1999, 2007, and 2008. Our data show that these flows begin depositing at higher slope gradients and are also more mobile than hillslope debris flows reported by other authors. Above a 19° slope, erosion is initiated independent of the distance along the flowpath. Using the isopach maps and associated field observations, we have found a relationship between ground slope and patterns in deposition volume. We have used this finding as a basis for an empirical model that enables an estimate of the total travel distance and final thickness of future debris flows to be calculated. This has enabled us to identify areas of the town which are at risk; some of these are not obvious without this analysis. This model is notable for its simplicity, which allows future debris flow characteristics to be predicted without the need to determine the precise fluid dynamic parameters of the flow such as viscosity and velocity, which are required to implement more complex models.
    Mots-clés : Debris flow, Geohazards, Icelandic Westfjords, LiDAR.

  • Corenblit Dov, Steiger Johannes et Delmotte Sébastien« Abiotic, residual and functional components of landforms », Earth Surface Processes and Landforms, 35 (14), p. 1744–1750.

  • Corenblit Dov, Steiger Johannes et Tabacchi Eric« Biogeomorphologic succession dynamics in a Mediterranean river system », Ecography, 33 (6), p. 1136–1148. DOI : DOI: 10.1002/rra.2618.

  • Corona C., Guiot J., Edouard J. L., Chalié F., Büntgen U., Nola P. et Urbinati C.« Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings », Climate of the Past, 6 (3), p. 379-400. DOI : 10.5194/cp-6-379-2010.

  • Corona Christophe, Rovéra Georges, Lopez Saez Jérôme, Stoffel Markus et Perfettini Pascal« Spatio-temporal reconstruction of snow avalanche activity using tree rings: Pierres Jean Jeanne avalanche talus, Massif de l'Oisans, France », Catena, 83 (2-3), p. 107-118. DOI : 10.1016/j.catena.2010.08.004.

  • Decaulne Armelle et Sæmundsson Þ.« Distribution and frequency of snow-avalanche debris transfer in the distal part of colluvial cones in Central North Iceland », Geografiska Annaler: Series A, Physical Geography, p. 177-187.
    Mots-clés : far distal area, Lichenometry, Northern Iceland, Schmidt hammer, snow-avalanche deposits.

  • Etienne Samuel et Paris Raphaël« Boulder accumulations related to storms on the south coast of the Reykjanes Peninsula (Iceland) », Geomorphology, 114 (1–2), p. 55-70. (Rock Coast Geomorphology). DOI : 10.1016/j.geomorph.2009.02.008.
    Résumé : Coastal boulder accumulations are often mentioned in the literature, even though their interpretation remains difficult, especially along rock coasts affected both by storms and tsunamis. Studies on the geomorphic impact of such high-energy events are actually of great interest, since their intensity and frequency are key issues for the future evolution of coasts in the framework of the global change. The southwest coast of Iceland faces the powerful storms of the North Atlantic Ocean, with wave heights of more than 15 m. The probability for past and present tsunamis to hit this coast is very low. In this paper, we describe boulder accumulations along the volcanic rock coast of Reykjanes (southwest Iceland). They consist of cliff-top boulders, clusters and ridges, beaches, and boulder fields. Large boulders, up to 70 t in weight, have been transported and deposited up to 65 m inland (6 masl). The maximum limit of boulder deposition and driftwood was found respectively 210 m and 550 m inland. Storms appear to be a predominant factor in the geomorphic evolution of Reykjanes coasts. Our observations also give new insight for the interpretation of coastal boulder accumulations. Processes of erosion and deposition by tsunamis are a rising topic in the literature, and the effects of recurrent and powerful storms are neglected.
    Mots-clés : Cliff-top boulders, coastal geomorphology, North-Atlantic, Storm deposits, Tsunami.

  • Ettinger S.« Geomorphologic field observations as a tool to improve lahar hazard assessment on the Southwestern flank of Cotopaxi volcano, Ecuador », AGU Fall Meeting Abstracts, 11, p. 1135.
    Résumé : Syn-eruptive lahars are a prominent hazard at snow- and ice-clad volcanoes such as Cotopaxi, Ecuador. These large volcanic mudflows follow existing stream channels and often change valley morphology. Assessing lahar hazard at Cotopaxi is based primarily on the study of sediments deposited from past events. This research describes the hazard by using geomorphologic observations to examine deposits and infer emplacement mechanisms and flow dynamics of past lahars. In addition, the morphological characteristics and other topography-related parameters in areas affected by lahars are used to assess the hazard from potential future lahars. Geomorphologic field observations were made in three drainages and the adjacent floodplain on the southwestern flank of Cotopaxi volcano. In this area, many sites of natural exposure of lahar deposits are masked or altered by other surface processes. Deposits were therefore mapped and classified according to their origin as fluvial, torrential or gravitational geoforms. Emphasizing the analysis of torrential (lahar) deposits, the field survey reveals considerable differences in types of deposit and distribution of deposit volume along the longitudinal valley profiles. While sediment quantity decreases downstream in the two Northern drainages, the Southern drainage holds concentrations of large amounts of sediment in the form of lobes between the middle and lower reaches, in proximity of the floodplain. Spatial data analysis shows that the type, morphology and location of the deposits are related to the morphometry of the drainage basin and the channel. The main processes impacting valley and channel morphology during a lahar were classified into three categories: aggradation, incision and widening. Erosional features and spatial distribution of deposits in the valley cross-section and along the longitudinal profile were indicators of timing of emplacement. These observations suggest that an eruptive event at Cotopaxi most likely generates several lahars; each having different sediment-water ratios. Early phases of water-poor flows leave terraces or lobe-shaped deposits. Successive watery flows incise previously deposited material and redistribute outwash farther downstream, reshaping the channel. A comparison of present morphological conditions along the channels of the three drainages revealed common slope, width and deposit volumes that will influence erosion or deposition by future lahars. Erosion and/or deposition in the drainages determine the sediment outflow on the floodplain. Correlating areas of major sediment concentration with specific morphological conditions identified sites of potential sediment storage or bulking risk in all three drainages. Using a geomorphologic approach to assess lahar hazard at Cotopaxi has proven to improve the understanding of the role of drainage morphology in lahar dynamics. Furthermore, the results contribute essential empirical information to developing lahar hazard scenarii for low-lying areas potentially affected by future lahars.
    Mots-clés : [1810] HYDROLOGY / Debris flow and landslides, [1824] HYDROLOGY / Geomorphology: general, [8404] VOLCANOLOGY / Volcanoclastic deposits, [8488] VOLCANOLOGY / Volcanic hazards and risks.

  • Giachetti Thomas, Druitt T., Burgisser Alain, Arbaret Laurent et Galven C.« Bubble nucleation, growth and coalescence during the 1997 Vulcanian explosions of Soufrière Hills Volcano, Montserrat », Journal of Volcanology and Geothermal Research, 193 (3-4), p. 215-231. DOI : 10.1016/j.jvolgeores.2010.04.001.
    Résumé : Soufrière Hills Volcano had two periods of repetitive Vulcanian activity in 1997. Each explosion discharged the contents of the upper 0.5–2 km of the conduit as pyroclastic flows and fallout: frothy pumices from a deep, gas-rich zone, lava and breadcrust bombs from a degassed lava plug, and dense pumices from a transition zone. Vesicles constitute 1–66 vol.% of breadcrust bombs and 24–79% of pumices, all those larger than a few tens of µm being interconnected. Small vesicles (< few tens of µm) in all pyroclasts are interpreted as having formed syn-explosively, as shown by their presence in breadcrust bombs formed from originally non-vesicular magma. Most large vesicles (> few hundreds of µm) in pumices are interpreted as pre-dating explosion, implying pre-explosive conduit porosities up to 55%. About a sixth of large vesicles in pumices, and all those in breadcrust bombs, are angular voids formed by syn-explosive fracturing of amphibole phenocrysts. An intermediate-sized vesicle population formed by coalescence of the small syn-explosive bubbles. Bubble nucleation took place heterogeneously on titanomagnetite, number densities of which greatly exceed those of vesicles, and growth took place mainly by decompression. Development of pyroclast vesicle textures was controlled by the time interval between the onset of explosion–decompression and surface quench in contact with air. Lava-plug fragments entered the air quickly after fragmentation (not, vert, similar 10 s), so the interiors continued to vesiculate once the rinds had quenched, forming breadcrust bombs. Deeper, gas-rich magma took longer (not, vert, similar 50 s) to reach the surface, and vesiculation of resulting pumice clasts was essentially complete prior to surface quench. This accounts for the absence of breadcrusting on pumice clasts, and for the textural similarity between pyroclastic flow and fallout pumices, despite different thermal histories after leaving the vent. It also allowed syn-explosive coalescence to proceed further in the pumices than in the breadcrust bombs. Uniaxial boudinage of amphibole phenocrysts in pumices implies significant syn-explosive vesiculation even prior to magma fragmentation, probably in a zone of steep pressure gradient beneath the descending fragmentation front. Syn-explosive decompression rates estimated from vesicle number densities (> 0.3–6.5 MPa s− 1) are consistent with those predicted by previously published numerical models.
    Mots-clés : Amphibole boudinage, Bubble growth, Bubble nucleation, Coalescence, Soufrière Hills, Vesiculation, Vulcanian explosions.

  • Guiot Joel, Corona Christophe et ESCARSEL members« Growing Season Temperatures in Europe and Climate Forcings Over the Past 1400 Years », PLoS ONE, 5 (4), p. e9972. DOI : 10.1371/journal.pone.0009972.

  • Hall Kevin et André Marie-Françoise« Some further observations regarding " cryoplanation terraces " on Alexander Island », Antarctic Science, 22 (2), p. 175-183.
    Mots-clés : Antarctic., geomorphology.

  • Larrue Sébastien et Chiron Thomas« Les îles de Polynésie française face à l’aléa cyclonique », VertigO : la Revue Électronique en Sciences de l'Environnement, 10 (8), p. 14 p. DOI : 10.4000/vertigo.10558.
    Mots-clés : cyclone hazard, el Niño., French Polynesia, Mapping, tropical cyclone, tropical storm.

  • Larrue Sébastien, Meyer Jean Yves et Chiron Thomas« Anthropogenic Vegetation Contributions to Polynesia’s Social Heritage : The Legacy of Candlenut Tree (Aleurites moluccana) Forests and Bamboo (Schizostachyum glaucifolium) Groves on the Island of Tahiti. », Economic Botany, 64 (3), p. 329-339. DOI : 10.1007/s12231-010-9130-3.
    Résumé : In the tropical oceanic islands of the Pacific, vegetation patterns and dynamics are the result of plant dispersal capacities, the physical characteristics of the islands’ ecosystems, and natural disturbances. However, humans have profoundly modified native landscapes through habitat destruction and the introduction of animal and plant species. The candlenut tree Aleurites moluccana (Euphorbiaceae) and the Polynesian bamboo Schizostachyum glaucifolium (Poaceae), intentionally introduced as useful plants by the first Polynesian migrants at least 1,000 years ago, are now widely naturalized in the high volcanic islands of the Society archipelago (French Polynesia), but with an intriguing patchy distribution. The present study consists of a comparative analysis between the most recent, existing vegetation map and the known archeological sites on the island of Tahiti. Thirty-nine bamboo groves and 30 candlenut forests were identified and located using GIS and a Digital Elevation Model. The results show that the dispersal and distribution patterns of these two plant taxa are related to the presence and location of ancient sites of Polynesian occupation. The bamboo groves can be used as a bio-indicator of the presence of potential archeological sites. Their currently restricted distribution might reflect habitat requirements and poor dispersal capacities. The candlenut tree and the Polynesian bamboo are relicts of ancient Polynesian society that have persisted and remain integrated in the modern landscape. They can therefore be viewed as introduced species of high cultural heritage value.
    Mots-clés : Aleurites moluccana, archeological vestiges, Biogeography, ethnobotanical knowledge., introduced plants, Schizostachyum glaucifolium, seed dispersal, Tahiti.

  • Moreau Myrtille« Visual perception of changes in a high mountain landscape: the case of the retreat of the Évettes Glacier (Haute-Maurienne, northern French Alps) », Géomorphologie : Relief. Processus. Environnement, 2, p. 165-174.
    Mots-clés : geomorphosite, glacial retreat, landscape patrimony, marge proglaciaire, patrimoine paysager, perception, proglacial area, retrait glaciaire, valorisation.

  • Paris Raphael, Cachao Mario, Fournier Jérôme et Voldoire Olivier« Nannoliths abundance and distribution in tsunami deposits: example from the December 26, 2004 tsunami Lhok Nga (northwest Sumatra, Indonesia). », Géomorphologie : Relief. Processus. Environnement, p. 109-118.

  • Paris Raphael, Fournier J., Poizot Emmanuel, Etienne Samuel, Morin Julie, Lavigne Franck et Wassmer Patrick« Boulder and fine sediment transport and deposition by the 2004 tsunami in Lhok Nga (western Banda Aceh, Sumatra, Indonesia): a coupled offshore - onshore model. », Marine Geology, 268, p. 43-54.

  • Terry Peter, James et Etienne Samuel« Tempestuous times in the South Pacific islands », Science, 328, p. 428-429.
    Résumé : IN RECENT WEEKS, A NUMBER OF CENTRAL South Pacific nations and territories have suffered a battering from an onslaught of intense cyclones occurring in quick succession.
    Mots-clés : cyclone, enso, global change, natural hazards, pacific.

  • Terry Peter, James et Etienne Samuel« Stones from the dangerous winds: reef platform mega-clasts in the tropical Pacific Island », Natural Hazards, p. 3. DOI : 10.1007/s11069-010-9697-0.
    Mots-clés : boulders, coral reef, cyclone, extreme events, pacific.

  • Terry Peter, James et Etienne Samuel« Recent heightened tropical cyclone activity east of 180° in the South Pacific », Weather, 65 (7), p. 193-195.
    Résumé : Owing to their small land masses and widely dispersed nature within a vast expanse of ocean, whether or not individual South Pacific islands sustain significant damage by the passage of tropical cyclones would seem to be governed largely by chance. Indeed, many cyclones do not make landfall as they pass between scattered island groups on their poleward migration from lower latitudes where they develop. Yet, through February and March this year several archipelagic nations in the central South Pacific have been less fortunate and have been severely affected by a succession of intense tropical cyclones.
    Mots-clés : cyclone, enso, global change, natural hazards, pacific.

  • Torsvik Tomas, Paris Raphael, Didenkulova Irina, Pelinovsky Efim, Belousov Alexander et Belousova Marina« Numerical simulation of explosive tsunami wave generation and propagation in Karymskoye Lake, Russia », Natural Hazards and Earth System Sciences, 10 (11), p. 105-119.

  • Wassmer Patrick, Schneider Jean-Luc, Fonfrège A.M., Lavigne Franck, Paris Raphael et Gomez Christopher« Use of anisotropy of magnetic susceptibility (AMS) in the study of tsunami deposits: application to the 2004 deposits on the eastern coast of Banda Aceh, North Sumatra, Indonesia. », Marine Geology, 275, p. 255-272.

C-ACT - Communications avec publication dans des actes


  • Beauger Aude, Peiry Jean-Luc, Garreau Alexandre et Voldoire Olivier« Benthic diatom and macroinvertebrate communities from the impacted bypass channel of Poutès, upper Allier River (France): preliminary results before the dam removal. », in I.S. Rivers 2015, Lyon, France.
    Résumé : For the first time in France a dam is being removed in order to restore ecological and sediment continuity and to allow salmon migration. This modification of the dam of Poutès configuration allows the establishment of a long-term study. The first step is the evaluation of the geomorphological, sedimentary and ecological characteristics before the works in a reach of 21km including the bypassed section. This analysis is based on the study of diatoms and benthic macroinvertebrates collected upstream of the dam, in the bypassed section, and downstream of the penstock pipe release. The results show the impact of the dam on communities arising from a change in the water quality, but also habitats including the presence of very long and deep pools in the bypassed section, which alternate with rapids, which change the river dynamics of watercourse.
    Mots-clés : Benthic macroinvertebrates, bypass channel, Dam impacts, diatoms, longitudinal reach.

  • Peiry Jean-Luc, Voldoire Olivier et Sakho M« Ressources et qualité de l'eau sur le territoire de recherche de l'OHMi Tessékéré, Nord du Sénégal », in 3ème séminaire annuel du Labex DRIIHM, Aix en Provence, France : communication orale. (Labex DRIIHM).
    Résumé : Cette présentation fait le point des recherches en cours sur la ressource en eau et sa qualité physicochimique et microbienne sur le territoire de la Grande Muraille Verte sénégalaise. Sont examinées successivement les ressources en eau permanentes (forages profonds dans la nappe maastrichtienne) et les ressources intermittentes présentes dans les mares d'hivernage.
    Mots-clés : Grande Muraille Verte, ressource en eau, Sahel, Sénégal.

  • Poiraud Alexandre, Chevalier Mylène, Claeyssen Bertrand et Joly Bertrand« A geoheritage inventory for geoconservation and geotourism in the Regional Natural Park of Vercors (French Alps): INPG adjustment », in International Congress ”Geoheritage Inventories: Challenges, Achievements and Perspectives”, Toulouse, Toulouse, France.
    Résumé : The present study deals with the geoheritage inventory of the PNR of Vercors and its contribution to strategic territorial analysis and geotouristic development. Based on the national inventory methodology, the Vercors inventory were adapted and analyzed by a statistical way. The multivariate analysis provided fundamental elements on the inventory structure which are the base of a classification of the 79 geosites into 9 management groups. Those groups constitute the basement of the whole educational-touristic geoheritage project of the Vercor's PNR.
    Mots-clés : Geoheritage, geomorphology, Inventory.

  • Maleval Véronique« Les apports sédimentaires directs au barrage SMBA », in Workshop SIGMED, Rélizane, Algeria.
    Résumé : L'objectif est l'évaluation des apports directs au lac, c'est-à-dire sans passer par le réseau hydrographique, pour compléter les données des volumes de sédiments issus du BV et transitant par le réseau hydrographique. Ce sont donc les sédiments issus de l'érosion littorale et de l'érosion ravinaire qui sont étudiés.
    Mots-clés : érosion littorale, lac, Maroc, ravinement, SMBA.

  • Maleval Véronique« La topographie féminine vue par une géographe géomorphologue » (présenté à Les topographies féminines), in Les topographies féminines, Limoges, France, p. poster.
    Résumé : Le mélange de la morphologie et de l'art (peinture) a conduit à s'intéresser aux modelés caractéristiques d'une femme (seins, ongles, grossesse...), résultat d'une géodynamique du corps dans le temps. Qu'en est-il des modelés moins marqués comme les jambes? La réflexion montre que des détails corporels, tout comme le corps dans son ensemble, inscrits dans un contexte spatio-temporel permettent de parler de topographie féminine puisque le modelé témoigne d'un état à un instant donné.
    Mots-clés : artialisation, corps, géographie, morphologie.

C-COM - Communications orales dans une conférence nationale ou internationale


  • Hortobágyi Borbála, Burkart Andreas, Corenblit Dov, Peiry Jean-Luc, Steiger Johannes et Vautier Franck« 3D diachronic survey of riparian vegetation dynamics by photogrammetric methods: application of UAV and small airplane photographs » (Communication orale), présenté à EUGEO Budapest 2015, Budapest, Hungary.
    Mots-clés : 3D diachronic survey, Aerial Photographs, photogrammery, riparian vegetation dynamics, UAV.

  • Casado Ana et Peiry Jean-Luc« The thermal regime of abandoned channels: a preliminary analysis towards a water temperature model for the Allier River, France » (communication orale), présenté à EGU General Assembly Conference Abstracts, Vienne, Autriche.
    Résumé : The growing recognition of the ecological and water quality significance of river water temperature led to a large number of studies assessing thermal processes in streams and rivers. Yet, thermal processes in abandoned channels, which play an important role in maintaining water quality and biological diversity in fluvial corridors, have received minor attention. This study evaluates water temperature regimes in three abandoned channels of the Allier River, France, and quantifies the regime sensitivity to climatic (air temperature) and hydrological (surface and subsurface flow) influence. Analysis was conducted at annual and daily scales, and at two distinct sections of each abandoned channel: (i) the downstream section, which is well connected to the main stream channel, and (ii) the upstream section, which is poorly connected to the main stream channel and hence subject to greater influence of subsurface flow. Annual and daily water temperature regimes for all channels and sections were classified based on relative differences in the 'shape' (timing) and the 'magnitude' (size) of the thermographs. The climatic and hydrological sensitivity of water temperature regimes was quantified using a Sensitivity Index. Analysis at the annual scale revealed relative similarity in patterns of thermal response over time, with clear differentiation between upstream and downstream channel sections in all sites. Water temperature regimes in the upstream channel sections were strongly linked to subsurface water temperature in terms of both timing and size of the annual thermograph; water temperature regimes in the downstream channel sections were more sensitive to air and river water temperature, especially regarding the timing of the annual regimes. Although annual regimes of water temperature exhibited distinct patterns that were similar across sites and over time, analysis of daily water temperature regimes revealed broad differences within and between sites. Day-to-day sequencing of similar classes of diurnal regime varied over the year, and between consecutive years. Furthermore, the direction and strength of climatic and hydrological sensitivity of daily water temperature regimes varied over time, and between sites. Temporal and spatial variability of diurnal regime class sequencing and sensitivity indicates complex climatic and hydrologic influence on water temperature variability, strongly related to the morphology of each site. Identifying thresholds of climatic and hydrologic influence, as well as temporal and spatial variations in the strength of climatic and hydrologic influence, is the key to further development of predictive models of water temperature in the abandoned channels of the Allier River.
  • Mayoral Pascual, A.,« An integrated geoarchaeological approach to assess human forcing on landscape : evolution of an Iron Age oppidum (Auvergne, France). » (communication orale), présenté à XVII World UISPP congress, session 46 “Iron Age communities in western-central Europe: new approaches to landscape and identity, Burgos, Spain.

  • Mitroi Veronica, Deroubaix José-Frédéric, Vinçon-Leite Brigitte, Lacroix Gérard, Bernard Cécile, Arnaud Catherine, Maleval Véronique et Humbert Jean-François« Que nous dit un projet de co-construction, entre scientifiques et gestionnaires, des indicateurs de qualité sur la gestion des plans d'eau urbains d'Ile-de-France? » (Communication orale), présenté à Vulnérabilité et résilience des écosystèmes continentaux et marins, Marseille, France.
    Résumé : Contribution à la construction d'une méthodologie pour l'évaluation de la qualité et des fonctions des écosysèmes lentiques franciliens et proposition de stratégies pour une meilleure intégration dans les politiques de la ville en prenant en considération les aspects écologiques, de gestion et d'usages sociaux.
    Mots-clés : gestion, Ile-de-France, lacs périurbains, perception, qualité.
  • Peiry, J.-L.« Etude de la remobilisation des sédiments suite au réaménagement du barrage de Poutès (haut Allier) » (communication orale), présenté à Rencontres Migrateurs 2014, Association LOGRAMI, Poitiers, France.
  • Roussel Erwan, Toumazet Jean-Pierre, Florez Marta, Vautier Franck et Dousteyssier Bertand« Assessing spatial trends of cultural stone weathering intensity using a hardness tester: The case of Manglieu Saint-Sébastien church (France) » (communication orale), présenté à 27 April - 02 May EGU General Assembly, Vienne, Autriche.
  • Peiry Jean-Luc« Suivi hydromorphologique et biologique sur le site de Poutès. » (communication orale), présenté à Des saumons et des hommes 2 ; 20 ans après, bilan et perspectives, Brioude (France).

  • Peiry, J.-L.« Géomorphologie et hydrologie des zones humides » (communication orale), présenté à Conférence « Les journées de l’eau du CNRS », Paris, France.
  • Roussel Erwan et Chenet Marie« Postglacial rockfalls controls on environmental partitioning of the Haute-Romanche valley (Massif des Écrins, french Alps) » (communication orale), présenté à 8th IAG International Conference on Geomorphology - Paris 2013, Paris.
    Résumé : The Haute-Romanche valley, located in the Massif des Écrins, was widely glaciated during the LGM. Nowadays, the Romanche river is an effluent of two separated glaciers: the Clot des Cavales and the Plate des Agneaux. From the current glaciers fronts to the downstream neoglacial moraines, five successive rockfalls were identified. Their locations are probably linked to preferential areas of postglacial debutressing expression. These large rockfalls produce a semi-permanent environmental partitioning of the valley by controlling sediment flux and fluvial patterns. The objectives of the study are to quantitatively assess the partitioning functions of rockfalls of various volume on the streams long profiles, the downstream fluvial pattern succession and the spatial distribution of archaeological evidences. The topographic surveys of the Haute-Romanche valley floor and rockfalls were done using terrestrial multi-image photogrammetry coupled to a set of DGPS ground control points. The long profiles of the rivers were achieved with DGPS survey. Volumes of rockfalls were estimated by topographic modeling and volumetric computation using GIS software resources. Fluvial pattern analysis and archaeological mapping were completed based on photo-interpretation and field observations. Results show that river channel morphology is highly dependent of rockfall location and volume. Consequently, the downstream river patterns succession is deeply disturbed inducing a long-term segmentation of the fluvial continuum. This longitudinal partitioning of hydro-sedimentary dynamics has potentially major ecological, geoarchaeological and management implications.

C-AFF - Affiches / posters dans une conférence nationale ou internationale


  • Maleval Véronique, Thierry , Moreau et Cerbelaud Fabien« Entre perception et réalité cartographique : synthèse des résultats géographiques de l'évolution paysagère des lacs de Créteil, Enghien-Les-Bains et Saint-Quentin en Yvelines. » (poster), présenté à .
    Résumé : L'évolution paysagère de 3 lacs urbains d'Ile-De-France, a été caractérisée par photo-interprétation pour 3 périodes, entre 1950 et 2014. Les résultats montrent que l'environnement lacustre a été profondément modifié (sauf pour Enghien) entre 1950 et 1990 : sans surprise, les espaces dédiés à l'agriculture on reculé au profit de l'urbanisation et, pour Créteil et Saint-Quentin, des espaces verts ont été aménagés en périphérie du milieu aquatique. Ces parcs de nature anthropisée, accessibles aux citadins, assurent à la fois les fonctions sociale, récréative et esthétique dans l'environnement hyper-urbanisé d'Ile-de-France.
    Mots-clés : lac urbain, nature en ville, occupation du sol, paysages.

  • Garofano-Gomez Virginia, Corenblit Dov, Steiger Johannes, Moulia Bruno, Ploquin Stéphane, Chaleil Patrice, Forestier Olivier, Evette André, Gonzalez Eduardo, Hortobagyi Borbala et Lambs Luc« Response of black poplar (Populus nigra L.) to hydrogeomorphological constraints: a semi-controlled ex situ experiment » (poster), présenté à , Vol., La ZABR et le GRAIE. (Recherches et actions au service des fleuves et grandes rivières).
    Résumé : absent
    Mots-clés : hydro-geomorphologie, peuplier noir, populus nigra L..

  • Garófano-Gómez Virginia, Corenblit Dov, Steiger Johannes, Moulia Bruno, Ploquin Stéphane, Chaleil Patrice, Forestier Olivier, Evette André, Hortobágyi Borbála et Lambs Luc« Response of black poplar (Populus nigra L.) to hydrogeomorphological constraints: a semi-controlled ex situ experiment » (poster), présenté à I.S.Rivers - 2e Conférence Internationale ”Recherches et Actions au service des fleuves et grandes rivières”.
    Mots-clés : Mechanical constraints, Populus nigra L, positive niche construction, response traits, sediment burial.

  • Larrue Sébastien, Daehler Curtis C., Meyer Jean Yves, Pouteau Robin et Voldoire Olivier« Distribution, abundance and photosynthetic characteristics of the invasive tree Spathodea campanulata on the island of Tahiti (South Pacific Ocean) » (Poster), présenté à EMAPi 2015: 13th International Conference of Ecology and Management of Alien Plant Invasions.
    Résumé : Successful invasion is often a combination of species characteristics (or invasiveness) and habitat suitability (or invasibility). Our objective was to identify preferred habitats and suitable environmental conditions for the African tulip tree Spathodea campanulata (Bignoniaceae), one of the most invasive alien tree in the tropical island of Tahiti (South Pacific Ocean), in relation with its photosynthesis capacity. Spathodea abundance and leaf Chlorophyll fluorescence was examined in relation to topography and micro-climate along an elevational transect between 140 m and 1,300 m. Results show that Spathodea is (1) present up to 1,240 m where the mean daily temperature is 14.7°C, (2) is able to colonize slopes of more than 45°, (3) is over-represented in the elevational range 140-540 m as well as in the less disturbed forests found between 940 m and 1,040 m, suggesting a high threat for indigenous and endemic plants. Between 541-840 m Spathodea is under-represented supporting that this range is a non-preferred environment probably due to micro-climate conditions with punctual extreme events in temperature and air dryness. Major infestations on the island of Tahiti was recently reported on the leeward (drier) west coast, but Spathodea has also been recently found on the slopes of the windward (wetter) east coast. Chlorophyll fluorescence measurements indicate a high photosynthetic capacity among Spathodea in wet environments from sea level up to high elevations, suggesting that Spathodea will become an abundant invader on most of the island of Tahiti. Lien poster :
    Mots-clés : elevation ranges, Invasive species, leaf chlorophyll fluorescence, micro-climate, Spathodea campanulata, Tahiti..

  • Metz Meike, Egger Gregory, Díaz María, Schmidtlein Sebastian, Dister Emil, Garófano-Gómez Virginia, Steiger Johannes, Hortobágyi Borbála et Corenblit Dov« Process-oriented ecological analysis of a dynamic riparian ecosystem: the lower river Allier (France) » (poster), présenté à I.S.Rivers - 2e Conférence Internationale ”Recherches et Actions au service des fleuves et grandes rivières”.
    Mots-clés : floodplain vegetation, river Allier, spatio-temporal processes, vegetation succession.

  • Metz Meike, Egger Gregory, Díaz María, Schmidtlein Sebastian, Dister Emil, Garófano-Gómez Virginia, Steiger Johannes, Hortobágyi Borbála et Corenblit Dov Jean-François« Process-oriented ecological analysis of a dynamic riparian ecosystem: the lower river Allier (France) » (Poster), présenté à 2nd International Conference on Integrative Sciences and Sustainable Development of Rivers - I.S. RIVERS. Programme and abstracts. (ZABR & GRAIE).
    Mots-clés : floodplain vegetation, river Allier, spatio-temporal processes, vegetation succession.

  • Terasmaa Jaanus, Bartout Pascal, Marzecova Agata, Touchart Laurent, Koff Tiiu, Choffel Quentin, Kapanen Galina, Maleval Véronique, Millot Camille, Qsair Zoubida et Vandel Egert« European perspectives on regional estimates of standing water bodies and the relevance of man-made ponds » (Poster), présenté à European Geosciences Union, General Assembly, Vienne, Autriche.
    Résumé : The majority of terrestrial standing water bodies (SWB) are small in size, however, their abundance and distribution is not fully known and they are under-represented in legislation. Also, the models for global inventories of SWB are so far not sufficiently designed for estimating the relative abundance of small SWB (below 0.2 ha) and provide differing estimates. In this pilot study, we suggest a bottom-up approach for estimating the number of SWB at EU-level that combines the ground-validated data on water bodies from state inventories and data from peer-generated map databases; we assess the inventories and relative importance of small terrestrial water bodies of two different countries, Estonia and France.

  • Peignelin Coline, Defive Emmanuelle, Poiraud Alexandre, Le Coeur Charles, Virmoux Clément, Vautier Franck, Roussel Erwan, Toumazet Jean-Pierre et Gunnell Yanni« Les " rivières de pierres " : une formation en marge des catégories classiques. Questions posées dans le cas du massif du Mézenc (Velay oriental, Sud-Est du Massif central, France). » (poster), présenté à AFEQ - CNF INQUA.
    Résumé : La province volcanique du Velay oriental (SE du Massif central) compte une forte concentration de pierriers d’origine et d’appellation diverses (éboulis, chirats), issus du démantèlement des affleurements rocheux (rebords de coulées et, surtout, dômes et intrusions phonolitiques). Parmi ces accumulations figurent les « rivières de pierres » ou blockstreams de la littérature anglophone. Il s’agit de langues de blocs métriques redressés en tous sens, sans matrice en surface, déconnectées des amonts pourvoyeurs (gélifraction) et présentes jusque sur des pentes très faibles. Elles ont souvent été assimilées par défaut à d'anciens glaciers rocheux et rattachées sur la base d’arguments morpho-stratigraphiques au Pléniglaciaire supérieur. Elles sont en fait d’origine et d’âge mal connu et ne répondent pas clairement au modèle classique d’un glacier rocheux de haute montagne. Les observations de terrain (caractères intrinsèques, rapports stratigraphiques avec les autres formations, position dans la topographie, distance aux zones-source, contexte structural...), suggèrent des processus de mise en place par fluage et/ou lavage qui restent à préciser, la possibilité d’une chenalisation des blocs par la topographie préexistante (ravines), et posent la question de l’âge, de l’efficacité des processus en jeu et de l’existence éventuelle de plusieurs générations. L’acquisition récente de photographies aériennes traitées en photogrammétrie (orthophotographies, MNT) doit permettre de préciser la description de l’organisation de surface (modelé, fabrique) révélatrice des contraintes liées aux processus de mise en place. D'autre part, les investigations géophysiques menées (GPR et tomographie électrique) pourraient apporter d'intéressants éléments de compréhension. Cette étude s’intègre au programme de recherche WRACC, financé par L’Etablissement Public Loire et le FEDER.
    Mots-clés : Eastern Velay, French Massif Central, Late Glacial, Massif Central Français, Mézenc, Morphologie et processus périglaciaires, Pleistocene.

  • Peiry J.-L., Beauger Aude, Celle-Jeanton H., Voldoire O. et Casado Casado, A.« SOHAL : système d'observation d'une annexe hydraulique de l'Allier » (poster), présenté à Conseil Régional Auvergne.
    Résumé : Ce poster à été présenté dans le cadre du colloque de restitution du CPER Auvergne, le 8 décembre 2014 à l'Hôtel de Région, Clermont-Ferrand. Ce poster synthétise les actions de recherche mise en oeuvre dans le cadre d'un système d'observation de bras morts de l'Allier.
    Mots-clés : Allier, bras mort, écohydrologie, hydroécologie, système d'observation.

  • Roussel Erwan, Gruson Soizic, Vautier Franck, Voldoire Olivier et André Marie-Françoise« Assessing spatial trends of cultural stone weathering intensity using a hardness tester: the case of Manglieu Saint-Sébastien church (France) » (poster), présenté à European Geosciences Union Meeting.
    Mots-clés : rock weathering, stone decay.

  • Roussel Erwan, Toumazet Jean-Pierre, Florez Marta, Vautier Franck et Dousteyssier Bertrand« Using airborne LiDAR in geoarchaeological contexts: Assessment of an automatic tool for the detection and the morphometric analysis of grazing archaeological structures (French Massif Central) » (poster), présenté à European Geosciences Union Meeting, 2014.
    Résumé : Airborne laser scanning (ALS) of archaeological regions of interest is nowadays a widely used and established method for accurate topographic and microtopographic survey. The penetration of the vegetation cover by the laser beam allows the reconstruction of reliable digital terrain models (DTM) of forested areas where traditional prospection methods are inefficient, time-consuming and non-exhaustive. The ALS technology provides the opportunity to discover new archaeological features hidden by vegetation and provides a comprehensive survey of cultural heritage sites within their environmental context. However, the post-processing of LiDAR points clouds produces a huge quantity of data in which relevant archaeological features are not easily detectable with common visualizing and analysing tools. Undoubtedly, there is an urgent need for automation of structures detection and morphometric extraction techniques, especially for the "archaeological desert" in densely forested areas. This presentation deals with the development of automatic detection procedures applied to archaeological structures located in the French Massif Central, in the western forested part of the Puy-de-Dôme volcano between 950 and 1100 m a.s.l.. These unknown archaeological sites were discovered by the March 2011 ALS mission and display a high density of subcircular depressions with a corridor access. The spatial organization of these depressions vary from isolated to aggregated or aligned features. Functionally, they appear to be former grazing constructions built from the medieval to the modern period. Similar grazing structures are known in other locations of the French Massif Central (Sancy, Artense, Cézallier) where the ground is vegetation-free.
    Mots-clés : archaeological structures, Automatic tool, Imagery analysis, LiDAR, Massif Central France.

  • André Marie-Françoise, Phalip Bruno, Roussel Erwan, Vautier Franck et Voldoire Olivier« Impact of cement repointing on rates of sandstone deterioration in medieval churches of the French Massif Central » (poster), présenté à 8th International Conference on Geomorphology.
    Mots-clés : restoration practices, stone decay.

  • Lefeuvre Marion, Florez Marta, Miras Yannick, Vautier Franck, Dousteyssier Bertrand, Roussel Erwan et Toumazet Jean-Pierre« Genesis of a cultural landscape : the Chaîne des puys (Massif central, France) » (poster), présenté à MINaH – Managing Inhabited Natural Heritage.

  • Poiraud Alexandre« Landslide inventory bimodality in volcanised tertiary basin of Puy-en-Velay (France) : a geoindicator of climate change and geomorphologic evolution » (poster), présenté à 8th IAG - International Conference on Geomorphology.
    Résumé : The inventory of more than 200 landslides in the volcanised tertiary basin of Puy-en-Velay (France) reveals a clear bimodality of theirdistribution. The surface magnitude/frequency curve of all the landslides determines 2 power-law adjustments i) the first one with a b = -1.54,corresponding to the ancient landslides and palaeolandslides and ii) the second one with a b = -0.51 corresponding to the historical andpresent-day landslides. The C14 dating of 4 landslides of the first group allows us to determine that Subboreal period was significant foractivation or reactivation of high mass movements. Thus, we conclude that these 2 populations of landslide are the expression of differentclimatic patterns characterised by different level of geomorphic activity. This geomorphic activity is expressed by the synthetic term b of thestatistical adjustments. Finally, the landslides, in the study area, seem to be a geoindicator of this climatic temporal diversity.
    Mots-clés : landslide, power-law, Velay.

  • Roussel Erwan et Chenet Marie« Postglacial rockfalls controls on environmental partitioning of the Haute-Romanche valley (Massif des Écrins, french Alps) » (poster), présenté à 8th International Conference on Geomorphology.
    Résumé : The Haute-Romanche valley, located in the Massif des Écrins, was widely glaciated during the LGM. Nowadays, the Romanche river is an effluent of two separated glaciers: the Clot des Cavales and the Plate des Agneaux. From the current glaciers fronts to the downstream neoglacial moraines, five successive rockfalls were identified. Their locations are probably linked to preferential areas of postglacial debutressing expression. These large rockfalls produce a semi-permanent environmental partitioning of the valley by controlling sediment flux and fluvial patterns. The objectives of the study are to quantitatively assess the partitioning functions of rockfalls of various volume on the streams long profiles, the downstream fluvial pattern succession and the spatial distribution of archaeological evidences. The topographic surveys of the Haute-Romanche valley floor and rockfalls were done using terrestrial multi-image photogrammetry coupled to a set of DGPS ground control points. The long profiles of the rivers were achieved with DGPS survey. Volumes of rockfalls were estimated by topographic modeling and volumetric computation using GIS software resources. Fluvial pattern analysis and archaeological mapping were completed based on photo-interpretation and field observations. Results show that river channel morphology is highly dependent of rockfall location and volume. Consequently, the downstream river patterns succession is deeply disturbed inducing a long-term segmentation of the fluvial continuum. This longitudinal partitioning of hydro-sedimentary dynamics has potentially major ecological, geoarchaeological and management implications.
    Mots-clés : Deglaciation, French Alps, Proglacial rivers, Rockfall.

  • Poiraud Alexandre« Coevolution of relief and landslides on a volcanic landscape. The bassin of Puy-en-Velay, Massif central, France » (poster), présenté à Q8 - Quaternaire 8.
    Résumé : Les glissements de terrain sont connus pour être un facteur d’évolution géomorphologique majeur en contexte orogénique au sein desquels ils sont de lourds contributeurs aux bilans érosifs. Dans les vieux massifs, la littérature portant sur la question est moins abondante. Pourtant, à la faveur d’un événement tectonique significatif, le rajeunissement du relief peut entraîner une recrudescence des dynamiques gravitaires et bousculer les équilibres géomorphologiques antérieurs. Le bassin du Puy-en-Velay a connu aux charnières mio-pliocène et plio-pleistocène un soulèvement d’ampleur et une tectonique compartimentée à l’origine d’une forte incision le long des drains principaux et d’une vigoureuse reprise d’érosion. Les systèmes de pente ont été déséquilibrés et les glissements de terrain jalonnant ces axes d’incision privilégiés ont été favorisés. A partir de l’étude de paléoglissements situés dans des contextes géomorphologiques marqués par la fossilisation des paléotopographies à 2 époques différentes, nous envisageons un modèle de co-évolution des vallées et des glissements et proposons quelques bilans géomorphologiques. Dans un premier temps, les glissements sont contraints par la morphologie des vallées et ne peuvent que rétrogresser, entraînant de fait un recul des corniches basaltiques sommitales. Le bilan recul/incision dicte ainsi le rapport entre les glissements et les vallées. Cette première phase reste cependant dominée par l’incision et le recul des têtes des cours d’eau qui colonisent rapidement l’amont des bassins versant et tentent de s’ajuster rapidement à la baisse relative du niveau de base. Dans un second temps, les profils longitudinaux se régularisent et l’incision diminue favorisant ainsi le recul des corniches et l’élargissement des vallées. A partir d’un certain niveau d’élargissement, les contraintes physiographiques ne sont plus un frein au développement morphologique des glissements et on observe une augmentation de la diversité des formes ainsi que des facteurs contrôlant la disposition de ces glissements.Ce modèle simple nous permet finalement de lier les niveaux d’instabilités gravitaires globaux au temps, au sein d’un cycle d’érosion.

  • Decaulne Armelle, Eggertsson Ó., Sæmundsson Thorsteinn, Laute K., Beylich A.A., POP Olympiu, Defive Emmanuelle et Larrue Sébastien« The EuroDendro project - Snow-avalanche frequency and magnitude in European Middle Mountain unravelled by dendrogeomorphological analyses » (poster), présenté à WorldDendro 2010 - 8th Conference on Dendrochronology.
    Résumé : The EuroDendro project (2009-2010) associates French, Icelandic, Norwegian and Romanian researchers to analyse the recurrence of geomorphic dynamics occurring on slopes with a dendrogeomorphological approach. Study sites are located in France (Auvergne), Iceland (Northwestern and Northern Iceland), Norway (Nordfjord) and Romania (South Carpaths Mountains), enabling to investigate various European middle mountain environments and different tree species impacted by similar processes. The aim of the study is to highlight the various responses of conifers and broad-leaved trees subjected to recurrent snow avalanches in similar cold environments. In a longer perspective, the EuroDendro project aims to analyse natural hazard for local populations in areas with a lack of historical records. The study sites are voluntarily selected outside the Alpine area to represent zones that are scarcely present in the international literature, whereas such territories offer great potentialities in a global change context.
    Mots-clés : avalanches, dendrogéomorphologie, Dendrogeomorphology, snow-avalanches.

  • Martinat Audrey« Apport des techniques de lasergrammétrie terrestre au suivi d'érosion des ravines du Massif du Sancy » (poster), présenté à Journées des Jeunes Géomorphologues.
    Résumé : Le secteur sur lequel la lasergrammétrie a été testé est le versant nord du Grand Dièdre dans le Massif du Sancy. Ce secteur est essentiellement composé de coulées pyroclastiques et de retombées cendreuses, qui constituent des matériaux très friables. De plus, les pentes sont supérieures à 25°, le secteur est très peu végétalisé et connaît un climat montagnard très prononcé. Ce site, qui est le siège de processus érosifs agressifs, est donc particulièrement approprié pour tester cette méthode de suivi d’érosion. Un scanner 3D longue portée de type Optech Ilris 3D a été utilisé car il présente l’avantage d’être extrêmement précis (7mm à 100 m de distance) et permet de couvrir de grandes surfaces en peu de temps et d’obtenir des données sur des terrains peu accessibles (Abellán et al., 2006 ; Heritage et al., 2007). Les relevés topographiques ont été obtenus avec une très haute résolution spatiale, le pas d’acquisition des données pouvant aller jusqu’à quelques millimètres à 100 m de distance. La topographie du terrain a été restituée sous la forme d’un nuage de points denses. Les résultats sont très prometteurs en matière de cartographie des changements géomorphologiques et de calculs de volumes. Toutefois, la lasergrammétrie présente un certains nombre de contraintes : poids du matériel à transporter sur le terrain, nécessité de poser et de relever les coordonnées de cibles, lourdeur du traitement des données.
    Mots-clés : lasergrammétrie terrestre, suivi d'érosion.

  • Poiraud Alexandre« The importance of morphostructural control on the ”long-term” landslides: a way for a prospective hazard mapping » (poster), présenté à EGU General Assembly 2010.
    Résumé : The climate change effect on hillslope dynamics is disciplinary or interdisciplinary studied to forecast the consequences of possible landslide reactivation that could be impact infrastructures. The two principal approaches of research are (i) the study of the present day geomorphologic processes and interpolate them according to evolving triggering factor conditions and (ii) the study of the relation between paleoclimate and landslide activity periods to eventually connect the global hillslope dynamic with the closest climatic pattern corresponding to IPCC forecasts. These kinds of studies are efficient but time-consuming and particularly complex. Another way of research, based on geomorphological observation, is used to analyze a watershed portion affected by numerous inherited (long term slide) and active landslides (recent or reactivate) in the Puy-en-Velay tertiary basin (hercynian mountain vulcanized during Miocene and Plio-pleistocene, Massif central, France). The relations between morphostructure, disconnection time of hillslope from the valley river and landslide spatial density and activity are studied. The two main controlling factors of landslides (active or inherited) along a hillslope gradient are (i) relative elevation of the top of granitic basement and (ii) disconnection time of the hillslope from the river. Three types of hillslopes are determined by their profiles, their geologic structures and their disconnection times, each one corresponding to a sensitivity level. By this approaches, it is possible to produce a "prospective hazard" map which determines the sensivity of hillslope related to climate change.
    Mots-clés : landslide, long-term, morphostructural control.

OS - Ouvrages scientifiques


  • Ettinger SusanneGeomorphological impact of lahars on the southwestern flank of Cotopaxi volcano, Ecuador : drainage system and alluvial fan, Clermont-Ferrand 2.
    Résumé : Pendant une éruption volcanique sur des sommets englacés, des coulées de débris syn-eruptifs,dénommées lahars, peuvent être générées par la fonte partiale de glaciers. Ce phénomène estbien connu sur le volcan Cotopaxi, Equateur. La présente étude concerne trois vallées et un cônede déjection sur le flanc sud-ouest de ce volcan. Une première analyse a été conduite par relevésde formes géomorphologiques dans ces vallées qui témoignent des processus d’érosion et desédimentation lors du passage de lahars dans le passé, notamment ceux du dernier événementéruptif datant de 1877 AD. Bien que les types des formes géomorphologiques déterminées sontles mêmes, leur distribution spatiale varie d’une vallée à l’autre en fonction d’une interaction deparamètres morphologiques locaux. Les conditions environnementales individuelles déterminentégalement le volume de l’écoulement, paramètre crucial dans la délimitation de zones de risques delahars dans les plaines adjacentes. Pour cela, une deuxième étude a été menée à grande échelle surle cône de déjection à l’exutoire de la vallée la plus au Sud des trois. Une analyse intégrale de la morphologiede surface et des affleurements naturels a été complétée par des données stratigraphiquesde subsurface obtenues via un sondage avec un Géoradar. Reconstituer l’architecture sédimentairede ce cône permet de visualiser la distribution spatiale de formes érosives et de dépôts. L’étude àrévélé que différentes parties du cône sont actives à des moments distincts et les épaisseurs dedépôts de lahars sont variables en fonction du type d’écoulement et de son volume. Ceci permetde relier les dynamiques géomorphologiques des plaines alluviales aux zones d’initiation de laharssur les flancs du volcan. Enfin, cette étude a débouché sur la mise en place d’une nouvelle fonctiondans le logiciel de modélisation de lahars LAHARZ prenant en compte l’incorporation progressive desédiment dans un contexte érosif dans les vallées, ce qui permet une meilleure délimitation de zonesde risque de lahars sur le cône.

  • Maleval Véronique, Picker Marion et Gabaude FlorentGéographie poétique et cartographie littéraire, PULIM, 292 p.
    Résumé : Dix géographes et dix littéraires réfléchissent en commun sur la notion de cartographie, aujourd'hui transversale à toutes les disciplines et souvent galvaudée dans le discours scientifique ou journalistique contemporain. A rebours de son usage inflationniste, les co-auteurs conservent au terme son ancrage territorial. D'instrument de connaissance du réel et de production de l'espace, la cartographie est devenue non seulement un thème littéraire, mais surtout un mode d'organisation du savoir, notamment en histoire de la littérature, ainsi qu'un mode d'investigation des textes, appréhendés sous l'angle de leur référentialité. Suspectée par Michel de Certeau, et d'autres à sa suite, de dépoétiser le réel, la représentation cartographique moderne est ici questionnée quant à ses présupposés épistémologiques, dans le but de restituer à la géographie sa dimension poétique. La cartographie elle-même n'en recèle pas moins une poéticité propre qui mérite d'être explorée, de même que la poétique des auteurs littéraires est susceptible d'être, au sens propre du terme, cartographiée, voire géoréférencée, et que peuvent converger dans l'analyse d'œuvres fictionnelles les approches géocritique et géomatique.

CH - Chapitres d'ouvrage


TH - Thèses


  • Casado Casado, Ana« Human impacts and fluvial metamorphosis : the effects of flow regulation on the hydrology, morphology and water temperature of the Sauce Grande River, Argentina. », Theses, Institut d’Optique Graduate School.
    Mots-clés : Barrage Paso de las Piedras, flow regulation, Fluvial forms, Fluvial landscape, Formes fluviales, Paso de las Piedras Dam, Paysage fluvial, Régime d’écoulement, Régulation hydrologique, River flow regime, river water temperature, Rivière Sauce Grande, Sauce Grande River, Température de l’eau.

  • Lefeuvre Marion« Contemporaneous vegetation dynamics in the Chaîne des Puys : Collectives pastures” », Theses, Université Blaise Pascal - Clermont-Ferrand II.
    Mots-clés : Chaîne des Puys, Chaîne des Puys (French Massif central), Dynamique végétale, Fermeture du paysage, Landscape closure, Landscape mosaic controlled by dynamically interacting ecological and anthropogenic drivers, Mosaïque phyto - morphologique anthropique, Vegetation dynam i cs.

  • Poiraud Alexandre« Les glissements de terrain dans le bassin tertiaire volcanisé du Puy-en-Velay (Massif central, France) : caractérisation, facteurs de contrôle et cartographie de l'aléa », Theses, Université Blaise Pascal - Clermont-Ferrand II.
    Mots-clés : Bassin du Puy-en-Velay, Coévolution relief/glissement, Glissement de terrain, Hazard mapping, Hazard modeling, landslide, Landslide/relief coevolution, Massif Central, Modélisation probabiliste, Risque gravitaire, Tertiary basin of Puy-en-Velay.

  • Roussel Erwan« Réponses des glaciers et des sandurs sud-islandais au réchauffement climatique post-petit âge glaciaire : Modalités et rythmes d'ajustement du continuum glacio-fluvial », Theses, Université Blaise Pascal - Clermont-Ferrand II.
    Mots-clés : Dynamiques glaciaires et fluvioglaciaires, Geomorphic impacts of post-LIA climate change, Glacial and fluvioglacial dynamics, Iceland, Impacts géomorphologiques du changement climatique post-PAG, Islande.

AP - Autres publications


  • Maleval Véronique et Pitois FrédéricEtude limnologique du lac de Saint-Germain de Confolens (Charente, France) - Résultats, Intern report, SEP du Confolentais, 60 p p.
    Résumé : Pour comprendre l'origine des problèmes de distribution d'eau potable (forts taux de MES et phosphore), le lac de Saint-Germain de Confolens, en Charente, a été instrumenté et suivi sur une année complète (mars 2015 - mars 2016) par le biais, notamment, de pièges à sédiments, de sondes thermiques et de prélèvements et analyses d'eau hebdomadaires. Les résultats montrent que 1) le tributaire du lac, l’Issoire, porte des flux significatifs de MES (1 810 t en 2015-16) et de phosphore (5,4 t) à la retenue; 2) la retenue a perdu 42 % de sa capacité utile pour l'AEP tant la sédimentation est importante (jusqu'à 11 cm pour l'année étudiée, soit 5 fois plus que les taux enregistrés dans les lacs bretons) ; 3) la masse d’eau est en fort déficit d’oxygène dissous, malgré la présence d’une aération artificielle qui ne parvient à remplir son rôle que durant 75 % de son temps d'action, contre 90 % prévus lors de son installation. Les principales causes à cette situation proviennent du bassin d'alimentation du lac, fortement agricole.
    Mots-clés : AEP, BV., lac de Saint-Germain de Confolens, occupation du sol, qualité des eaux, sédimentation.

  • shindo lisa, Belingard Christelle, Edouard Jean-Louis et Saulnier Mélanie« South-east France fir: new dendrochronological data from buildings and living trees. ».
    Résumé : Ring width data (1/100mm) of 31 fir trees and timber sites, from 1214 to 2009, in the south-east France, for dating projects, paleo-ecology studies and climate reconstructions.
    Mots-clés : Alps, Climate, Dating, dendrochronology, Fir, Timber.

  • Pierre-Brieuc Destombes et Maleval VéroniqueRapport final du projet thononais sur les berges lémaniques, Research Report, Ville de Thonon-les-Bains, 23 p p.
    Résumé : Après le diagnostic de l'érosion sur le littoral de Thonon les Bains et la détermination des zones à enjeux pour lesquelles des mesures ont été proposées sous forme de fiches actions, la phase 3 de l'étude donne pour chaque zone à enjeux la vitesse moyenne annuelle de recul du trait de côte (jusqu'à 1 m) et permet d'apprécier les évolutions morphologiques du littoral sur, parfois, une période de 4 ans.
    Mots-clés : érosion, Léman, sédimentation, Thonon.

  • André Marie-Françoise, Phalip Bruno, Voldoire Olivier, Vautier Franck et Roussel ErwanLa détérioration des motifs sculptés dans trois grès d’Angkor : influence des facteurs géologiques et environnementaux, Research Report, UNESCO - Comité International de Coordination pour la Sauvegarde et le développement du Site Historique d’Angkor, 19ème Session Technique, 4 p. p.
    Mots-clés : Angkor temples, geomorphology and weathering, stone decay.
  • André Marie-Françoise, Vautier Franck, Voldoire Olivier, Etienne Samuel, Mercier Denis, Corenblit Dov, Phalip Bruno et Roussel ErwanLe temple de Ta Keo : contribution au diagnostic de détérioration des parements sculptés et à la définition des futures stratégies de conservation et de valorisation, Rapport d’étape UNESCO. (17ème session plénière du Comité International de Coordination pour la Sauvegarde et le Développement du Site d’Angkor).

  • Laraque Alain, López JL, Steiger Johannes et Rosales J.Rapport de fin d’action ECOS-Nord VENEZUELA. Le rôle des plaines d’inondation de l’Orénoque dans le contrôle des processus hydro-sédimentaires : implications dans le fonctionnement et la biodiversité de cet écosystème tropical, Research Report, IRD, 58 p. p.
    Mots-clés : ECOS-Nord, Orénoque, Venezuela.

  • Maleval VéroniqueRapport final interne du programme sur la radioactivité des sédiments du lac de Saint-Pardoux (AREVA, Pe@rl), Contrat, AREVA - Pe@rl.
    Résumé : Ce rapport fait suite à de nombreux travaux visant à comprendre et localiser les zones de sédimentation dans les cours d'eau et zones humides associées, seuils et retenues situés en aval des rejets de la Division Minière de La Crouzille. L'étude porte sur les aspects mécaniques des processus de transports des sédiments en cours d'eau et sur l'étude du suivi de la sédimentation en rivières (La Couze et Le Ritord - suivi 2000 à 2002) et dans une retenue d'eau (le Lac de Saint Pardoux). Les mécanismes de sédimentation mettent en évidence les paramètres entrant en jeu : propriétés des sédiments, notamment leur granulométrie, débit, particularité géographique et/ou de végétation des cours d'eau, zone de fourniture.
    Mots-clés : débit liquide, débit solide, delta, processus de dépôt, Saint-Pardoux, sédimentation.

  • Rosales J., Diaz W., Navarro R., Méndez S., RodrÍguez M., Ortiz J., Castellanos B., Laraque Alain, Steiger Johannes, López J.L., Muller Etienne, Peiry Jean-Luc et Guyot Jean LoupDinamica biotico-hidro-sedimentologia en várzeas del bajo Río Orinoco, Estado Bolivar, Venezuela, Research Report, Universidad Nacional Experimental de Guayana.
    Mots-clés : Orénoque, Venezuela.