Université de Fribourg

Reconstructing spatio-temporal patterns of debris-flow activity using dendrogeomorphological methods

Bollschweiler, Michelle ; Stoffel, Markus ; Ehmisch, Melanie ; Monbaron, Michel

In: Geomorphology, 2007, vol. 87, no. 4, p. 337-351

Debris flows are a major threat in many parts of the Alps, where they repeatedly cause severe damage to infrastructure and transportation corridors or even loss of life. Nonetheless, the spatial behavior of past debris-flow activity and the analysis of areas affected during particular events have been widely neglected in reconstructions so far. It was therefore the purpose of this study to...

Université de Fribourg

Dynamics in debris-flow activity on a forested cone — A case study using different dendroecological approaches

Bollschweiler, Michelle ; Stoffel, Markus ; Schneuwly, Dominique M.

In: Catena, 2008, vol. 72, no. 1, p. 67-78

Dendrogeomorphological analyses of trees affected by debris flows have regularly been used to date past events. However, this method has always been limited to forested cones where trees registered the impact of previous events. The minimum age dating of trees growing in the debris deposits can, in contrast, provide information on the latest possible moment of past activity. In this paper, we...

Université de Fribourg

A review of studies dealing with tree rings and rockfall activity: the role of dendrogeomorphology in natural hazard research

Stoffel, Markus

In: Natural Hazards, 2006, vol. 39, no. 1, p. 51-70

Over the last few years, rockfall research has increasingly focused on hazard assessment and risk analysis. Input data on past rockfall activity were gathered from historical archives and lichenometric studies or were obtained through frequency–volume statistics. However, historical records are generally scarce, and lichenometry may only yield data with relatively low resolutions. On forested...

Université de Fribourg

Differentiating past events on a cone influenced by debris-flow and snow avalanche activity - a dendrogeomorphological approach

Stoffel, Markus ; Bollschweiler, Michelle ; Hassler, Gion-Reto

In: Earth Surface Processes and Landforms, 2006, vol. 31, no. 11, p. 1424 - 1437

Dendrogeomorphology was used to investigate past events on a cone affected by both debris flows and snow avalanches. We report on results of 520 cores from 251 injured Larix decidua Mill. and Picea abies (L.) Karst. trees sampled on the Birchbach cone (Swiss Alps). Detailed analysis of tree-ring sequences allowed dating of 561 growth disturbances in individual trees for a 252 yr...

Université de Fribourg

400 years of debris flow activity and triggering weather conditions: Ritigraben VS, Switzerland

Stoffel, Markus ; Lièvre, Igor ; Conus, Delphine ; Grichting, Michael A. ; Raetzo, Hugo ; Gärtner, Holger W. ; Monbaron, Michel

In: Arctic Antarctic and Alpine Research, 2005, vol. 37(3), p. 387-395

Three major rainfall events have caused considerable damage in the Valais region (Swiss Alps) since 1987. While important debris flows originating from periglacial environments were recorded during the August 1987 and September 1993 rainfall events, no debris flows occurred in October 2000. This paper aims at putting these large area events and the apparent increase in debris flow frequency into...