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Your search keyword '"Climatic change and climate impacts"' showing total 6 results
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6 results on '"Climatic change and climate impacts"'

1. Unravelling past flash flood activity in a forested mountain catchment of the Spanish Central System

Author

Clara Rodríguez-Morata, Raúl Sánchez-Salguero, Virginia Garófano-Gómez, J.M. Rubiales, Markus Stoffel, Juan Antonio Ballesteros-Cánovas, Laboratory of Dendrogeomorphology, Institute of Geological Sciences-University of Bern, Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), Université de Genève = University of Geneva (UNIGE)-Université de Genève = University of Geneva (UNIGE), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut d’Investigació per a la Gestió Integrada de Zones Costaneres (IGIC), Universitat Politècnica de València (UPV), Departamento de Silvopascicultura, ETSI de Montes, Universidad Politécnica de Madrid (UPM), Departamento de Ingeniería Forestal, Laboratorio de Dendrocronología, Universidad de Córdoba = University of Córdoba [Córdoba]-Universidad de Córdoba = University of Córdoba [Córdoba], Swiss Federal Research Institute (WSL), University of Geneva [Switzerland]-University of Geneva [Switzerland], Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), and Universidad de Córdoba [Cordoba]-Universidad de Córdoba [Cordoba]

Subjects
Mediterranean climate, 010504 meteorology & atmospheric sciences, Flash flood, Forest management, Dendrogeomorphology, 0207 environmental engineering, 02 engineering and technology, 01 natural sciences, Peninsula, Natural hazard, ddc:550, medicine, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, 020701 environmental engineering, 0105 earth and related environmental sciences, Water Science and Technology, ddc:333.7-333.9, Hydrology, Sierra de Guadarrama, geography, geography.geographical_feature_category, National park, Paleohydrology, Hydrometeorological triggers, [SHS.GEO]Humanities and Social Sciences/Geography, 15. Life on land, Seasonality, medicine.disease, Medio Ambiente, 13. Climate action, North Atlantic oscillation, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, [SDE]Environmental Sciences, Tree ring, Geology
Abstract

[EN] 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., This study has been partially funded by the projects IDEA-GesPPNN-163/2010 (OAPN - Organismo Autonomo de Parques Nacionales, Ministerio de Agricultura, Alimentacion y Medio Ambiente) and CGL2010-19274 (projects MAS Dendro-Avenidas) of the Spanish Ministry of Economy and Competitiveness. The authors sincerely acknowledge Marco Borga and other anonymous reviewer. Special recognition must be given to CENEAM, Montes de Valsain, OAPN and JCyL for providing information for this study. Specifically, they want to thank Javier Dones (Director of Montes de Valsain), Ramzi Touchan and Dave Meko for their support during the study, as well as Andres Diez and Gerardo Benito and all participants of the Tree-ring summer school carried out in 2012 in Valsain (Touchan et al., 2013). R. Sanchez-Salguero thanks the financial support from University of Cordoba-Campus de Excelencia Internacional-ceiA3.

Published
2015

2. Gully evolution and geomorphic adjustments of badlands to reforestation

Author

David R. Montgomery, Markus Stoffel, J.F. Martín-Duque, Christophe Corona, J. A. Ballesteros Cánovas, Ana Lucía, José María Bodoque, Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), University of Geneva [Switzerland]-University of Geneva [Switzerland], Department of Earth and Environmental Sciences, University of Geneva [Switzerland], Department of Geodynamics, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Faculty of Sciences, Center for Applied Geosciences, Eberhard Karls University Tübingen, Free University of Bozen-Bolzano, University of Castilla-La Mancha (UCLM), Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], Université de Genève = University of Geneva (UNIGE)-Université de Genève = University of Geneva (UNIGE), Université de Genève = University of Geneva (UNIGE), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, and Universidad de Castilla-La Mancha = University of Castilla-La Mancha (UCLM)

Subjects
Mediterranean climate, ddc:333.7-333.9, geography, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Landform, Reforestation, Soil science, Vegetation, [SHS.GEO]Humanities and Social Sciences/Geography, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Article, Aerial photography, Erosion, Afforestation, Physical geography, Channel (geography), Geology, 0105 earth and related environmental sciences
Abstract

Badlands and gullied areas are among those geomorphic environments with the highest erosion rates worldwide. Nevertheless, records of their evolution and their relations with anthropogenic land transformation are scarcer. Here we combine historical data with aerial photographs and tree-ring records to reconstruct the evolution of a badland in a Mediterranean environment of Central Spain. Historical sources suggest an anthropogenic origin of this badland landscape, caused by intense quarrying activities during the 18th century. Aerial photographs allowed detection of dramatic geomorphic changes and the evolution of an emerging vegetation cover since the 1960s, due to widespread reforestation. Finally, tree-ring analyses of exposed roots allowed quantification of recent channel incision of the main gully, and sheet erosion processes. Our results suggest that reforestation practices have influenced the initiation of an episode of incision in the main channel in the 1980s, through the hypothesized creation of disequilibrium in water-sediment balance following decoupling of hillslopes from channel processes. These findings imply an asymmetry in the geomorphic response of badlands to erosion such that in the early evolution stages, vegetation removal results in gullying, but that reforestation alone does not necessarily stabilize the landforms and may even promote renewed incision.

Published
2017

3. Implementation of Aerosol-Cloud Interaction within WRF-CHIMERE Online Coupled Model: Evaluation and Investigation of the Indirect Radiative Effect from Anthropogenic Emission Reduction on the Benelux Union

Author

Adrien Deroubaix, Paolo Tuccella, Régis Briant, Dmitry Khvorostyanov, Guillaume Siour, Laurent Menut, Solène Turquety, Sylvain Mailler, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), NUMTECH, Department of Physical and Chemical Sciences [L'Aquila] (DSFC), Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), Centre of Excellence CETEMPS, Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), Université de Genève = University of Geneva (UNIGE)-Université de Genève = University of Geneva (UNIGE), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de l'Environnement Industriel et des Risques (INERIS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Università degli Studi dell'Aquila (UNIVAQ), University of Geneva [Switzerland]-University of Geneva [Switzerland], Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), TROPO - LATMOS, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Università degli Studi dell'Aquila [L'Aquila] (UNIVAQ.IT), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
model evaluation, Atmospheric Science, 010504 meteorology & atmospheric sciences, Aerosol indirect effect, lcsh:QC851-999, 010501 environmental sciences, Environmental Science (miscellaneous), Atmospheric sciences, complex mixtures, 01 natural sciences, Cloud condensation nuclei, Online model, Precipitation, Model evaluation, Air quality index, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], ddc:333.7-333.9, Longwave, aerosol indirect effect, Aerosol, meteorology-chemistry coupled model, WRF-CHIMERE model, online model, 13. Climate action, Weather Research and Forecasting Model, Meteorology-chemistry coupled model, Environmental science, lcsh:Meteorology. Climatology, Satellite, sense organs, Shortwave
Abstract

The indirect effects of aerosol are particularly important over regions where meteorological conditions and aerosol content are favourable to cloud formation. This was observed during the Intensive Cloud Aerosol Measurement Campaign (IMPACT) (European Integrated project on Aerosol Cloud Climate and Air quality Interaction (EUCAARI) project) in the Benelux Union during May 2008. To better understand this cloud formation variability, the indirect effects of aerosol have been included within the WRF-CHIMERE online model. By comparing model results to the aircraft measurements of IMPACT, to surface measurements from EMEP and AIRBASE and to MODIS satellite measurements, we showed that the model is able to simulate the variability and order of magnitude of the observed number of condensation nuclei (CN), even if some differences are identified for specific aerosol size and location. To quantify the impact of the local anthropogenic emissions on cloud formation, a sensitivity study is performed by halving the surface emissions fluxes. It is shown that the indirect radiative effect (IRE) at the surface is positive for both shortwave and longwave with a net warming of +0.99 W/m2. In addition, important instantaneous changes are modelled at local scale with up to &plusmn, 6 &deg, C for temperatures and &plusmn, 50 mm/day for precipitation.

Published
2019

4. A New Tree-Ring-Based, Semi-Quantitative Approach for the Determination of Snow Avalanche Events: use of Classification Trees for Validation

Author

Markus Stoffel, Vincent Jomelli, Nicolas Eckert, Michaël Deschatres, Delphine Grancher, Daniel Brunstein, Christophe Corona, Romain Schläppy, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Dendrolab.ch [Bern], Institute of Geological Sciences [Bern], University of Bern-University of Bern, Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), University of Geneva [Switzerland]-University of Geneva [Switzerland], Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), ANR-09-RISK-0007,MOPERA,MOdélisation Probabiliste pour l'Evaluation du Risque Avalanche(2009), Université Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Dendrogeomorphology, Department of Geosciences, Centre National de la Recherche Scientifique (CNRS)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne (UCA), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Panthéon-Sorbonne (UP1), Institute of Computer Science and Applied Mathematics (IAM), University of Bern, Institute of Computer Science and Applied Mathematics (ISCAM), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne (UCA)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Université de Genève = University of Geneva (UNIGE)-Université de Genève = University of Geneva (UNIGE), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), and Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)

Subjects
010504 meteorology & atmospheric sciences, CHAMONIX, [SDE.MCG]Environmental Sciences/Global Changes, 010502 geochemistry & geophysics, 01 natural sciences, DENDROMETRIE, ANALYSE STATISTIQUE, EPA, CHAMONIX, AVALANCHE, DENDROMETRIE, GEOMORPHOLOGIE, Dendrochronology, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, ANALYSE STATISTIQUE, ddc:333.7-333.9, Global and Planetary Change, Avalanche hazard, [SDE.IE]Environmental Sciences/Environmental Engineering, GEOMORPHOLOGIE, EPA, Snow, [SDE.ES]Environmental Sciences/Environmental and Society, [SDE]Environmental Sciences, Physical geography, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, AVALANCHE, Semi quantitative, Geology
Abstract

International audience; On forested paths, dendrogeomorphology has been demonstrated to represent a powerful Vincent Jomelli* tool to reconstruct past activity of avalanches, an indispensable step in avalanche hazard Delphine Grancher* assessment. Several quantitative and qualitative approaches have been shown to yield Markus Stoffel † ‡ reasonable event chronologies but the question of the completeness of tree-ring records remains debatable. Here, we present an alternative semi-quantitative approach for the Christophe Corona † determination of past snow avalanche events. The approach relies on the assessment of Daniel Brunstein* the number and position of disturbed trees within avalanche paths as well as on the Nicolas Eckert § and intensity of reactions in trees. In order to demonstrate that no bias was induced by the dendrogeomorphic expert, we carry out a statistical evaluation (Classification and Regres-Michael Deschatres § sion Trees, or CART) of the approach. Results point to the consistency and replicability *Laboratoire de Géographie Physique, of the procedure and to the fact that the approach is not restricted to the identification of Université Panthéon-Sorbonne, UMR high-magnitude avalanches. Evaluation of the semi-quantitative approach is illustrated on 8591 CNRS, 1 place Aristide Briand, Fa well-documented path in Chamonix, French Alps. For the period 1905-2010, comparison 92195 Meudon cedex, France †Dendrolab.ch, Institute of Geological between the avalanche years recorded in a substantial database (Enquête Permanente sur Sciences, University of Berne, les Avalanches, or EPA) and those defined with dendrogeomorphic techniques shows that Baltzerstrasse 1 ‫ם‬ 3, CH-3012 Berne, the avalanche record reconstructed from tree-ring series contains 38% of the observed Switzerland events.

Published
2013

5. How much of the real avalanche activity can be captured with tree rings? An evaluation of classic dendrogeomorphic approaches and comparison with historical archives

Author

Didier Richard, Markus Stoffel, Laurent Astrade, Christophe Corona, Frédéric Berger, Mylène Bonnefoy, Jérôme Lopez Saez, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratory of Dendrogeomorphology, Department of Geosciences, Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), University of Geneva [Switzerland]-University of Geneva [Switzerland], Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
ddc:333.7-333.9, 010504 meteorology & atmospheric sciences, Meteorology, [SDE.MCG]Environmental Sciences/Global Changes, Dendrogeomorphology, 15. Life on land, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, Snow, Spatio-temporal analysis, 01 natural sciences, Tree (graph theory), 13. Climate action, General Earth and Planetary Sciences, Physical geography, Historical archives, Snow avalanches, Spatial extent, French Alps, Geology, 0105 earth and related environmental sciences
Abstract

International audience; In snow-rich areas, snow avalanches endanger settlements and cause heavy damage to infrastructure or transportation routes. In wooded avalanche paths, dendrogeomorphology has been used extensively to reconstruct snow avalanche histories or to complement existing archival records. Several authors noted (i) that avalanche chronologies reconstructed from tree rings would depend on the number of trees sampled, and on (ii) the minimum number of tree-ring responses; and (iii) that they would always represent minimum frequencies. These restrictions gave rise to the question of how much of the realavalancheactivity can be captured in tree-ring records. We therefore performed a dendrogeomorphic analysis based on 175 Larix decidua Mill. and 34 Picea abies (L.) Karst. trees from an extensively and accurately documented (1905-2010) avalanche path located in the Arve valley (French Alps) to obtain optimal thresholds for sample size and index values (i.e. percentage of responses in relation to the number of trees alive for a given year). Results clearly demonstrate that a sample size of ~ 100 trees is needed to obtain the best match between reconstruction (tree rings) and documentation (archives) while minimizing the inclusion of noise in the dendrogeomorphic record. Validation of the reconstruction (1771-2010) with historical archives shows that 13 undocumented events could be added to the archival record and that 43% of all documented events were deciphered with dendrogeomorphic techniques. The reconstruction of the spatial extent and reach of past snow avalanches matches with historical archives as far as the longitudinal extent of the largest avalanches is concerned. Yet, tree-ring records tend to underestimate runout elevations for a majority of minor events. Large discrepancies are also reported between the lateral limits derived with dendrogeomorphic techniques and the data reported in historical reports and hazard maps, with tree-ring data suggesting larger lateral spread of avalanche snow.

Published
2012

6. Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

Author

Markus Stoffel, Françoise Berger, A. Gotteland, Christophe Corona, F. Liébault, J. Lopez Saez, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratory of Dendrogeomorphology, Institute of Geological Sciences-University of Bern, Climatic Change and Climate Impacts Research Group, Institute for Environmental Sciences [Geneva] (ISE), University of Geneva [Switzerland]-University of Geneva [Switzerland], Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), and Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)

Subjects
010504 meteorology & atmospheric sciences, 0507 social and economic geography, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Spatial distribution, 01 natural sciences, lcsh:TD1-1066, Debris flow, lcsh:Environmental technology. Sanitary engineering, Digital elevation model, Geomorphology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, ddc:333.7-333.9, geography, geography.geographical_feature_category, biology, lcsh:QE1-996.5, 05 social sciences, lcsh:Geography. Anthropology. Recreation, Scots pine, Alluvial fan, Massif, 15. Life on land, biology.organism_classification, Debris, lcsh:Geology, Lidar, lcsh:G, [SDE]Environmental Sciences, General Earth and Planetary Sciences, HYDROGEOMORPHIC PROCESS, 050703 geography, Geology, MANIVAL TORRENT
Abstract

Hydrogeomorphic processes are a major threat in many parts of the Alps, where they periodically damage infrastructure, disrupt transportation corridors or even cause loss of life. Nonetheless, past torrential activity and the analysis of areas affected during particular events remain often imprecise. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris-flow activity in abandoned channels on the forested cone of the Manival torrent (Massif de la Chartreuse, French Prealps). A Light Detecting and Ranging (LiDAR) generated Digital Elevation Model (DEM) was used to identify five abandoned channels and related depositional forms (lobes, lateral levees) in the proximal alluvial fan of the torrent. A total of 156 Scots pine trees (Pinus sylvestris L.) with clear signs of debris flow events was analyzed and growth disturbances (GD) assessed, such as callus tissue, the onset of compression wood or abrupt growth suppression. In total, 375 GD were identified in the tree-ring samples, pointing to 13 debris-flow events for the period 1931–2008. While debris flows appear to be very common at Manival, they have only rarely propagated outside the main channel over the past 80 years. Furthermore, analysis of the spatial distribution of disturbed trees contributed to the identification of four patterns of debris-flow routing and led to the determination of three preferential breakout locations. Finally, the results of this study demonstrate that the temporal distribution of debris flows did not exhibit significant variations since the beginning of the 20th century.

Published
2011

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