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Spatio-temporal variability in debris-flow activity: a tree-ring study at Geisstriftbach (Swiss Alps) extending back to AD 1736

Stoffel, Markus ; Bollschweiler, Michelle ; Widmer, Susanne ; Sorg, Annina

In: Swiss Journal of Geosciences, 2010, vol. 103, no. 2, p. 283-292

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    Titel
    • Spatio-temporal variability in debris-flow activity: a tree-ring study at Geisstriftbach (Swiss Alps) extending back to AD 1736
    Autor
    • Stoffel, Markus. Laboratory of Dendrogeomorphology (dendrolab.ch), Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012, Bern, Switzerland
    • Bollschweiler, Michelle. Laboratory of Dendrogeomorphology (dendrolab.ch), Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012, Bern, Switzerland
    • Widmer, Susanne. Katastrophenvorsorge, Amt für Militär und Bevölkerungsschutz, Kanton Solothurn, Baselstrasse 40, 4500, Solothurn, Switzerland
    • Sorg, Annina. Department of Environmental Sciences, Forest Ecology, Institute of Terrestrial Ecosystems, Swiss Federal Institute of Technology of Zurich (ETHZ), 8092, Zurich, Switzerland
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Swiss Journal of Geosciences, 2010, vol. 103, no. 2, p. 283-292. SP Birkhäuser Verlag Basel
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:322379
    Summary
    Past debris-flow activity on the forested cone of the Geisstriftbach torrent (St. Niklaus, Valais, Swiss Alps) was assessed from growth disturbances in old conifer trees, providing a much improved record of past events. The study of 633 tree-ring sequences sampled from 252 European larch (Larix decidua Mill.), Norway spruce (Picea abies (L.) Karst.) and Silver birch (Betula pendula Roth.) trees allowed reconstruction of 53 debris-flow events since AD 1736. The spatial analysis of trees affected during particular events on the geomorphic map allowed for a spatial representation of individual events and a reconstruction of four flow patterns. Based on our results and Siegfried maps, we believe that before the formation of a dogleg near the cone apex in the late 1890s, debris flows preferentially used the channels located in the west-southwestern part of the Geisstriftbach cone. This study contributes to our understanding of debris-flow processes on cones and provides an example of how dendrogeomorphic techniques may help in the reconstruction and understanding of debris flows in Alpine areas