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Université de Fribourg

Spatial and temporal rockfall activity in a forest stand in the Swiss Prealps : a dendrogeomorphological case study

Perret, Simone ; Stoffel, Markus ; Kienholz, Hans

In: Geomorphology, 2006, vol. 74(1-4), p. 219-231

Rockfall is a major threat to settlements and transportation routes in large parts of the Alps. While protective forest stands in many locations undoubtedly reduce rockfall risk, little is known about the exact frequency and spatial distribution of rockfall activity in a given place or about how these parameters can be assessed. Therefore, the objective of the present study was to reconstruct...

Université de Fribourg

Assessing the protective effect of mountain forests against rockfall using a 3D simulation model

Stoffel, Markus ; Wehrli, André ; Kühne, Roderick ; Dorren, Luuk K.A. ; Perret, Simone ; Kienholz, Hans

In: Forest Ecology and Management, 2006, vol. 225, p. 1-3

We used one of the few rockfall models explicitly taking trees into account and compared the results obtained with the 3D simulation model RockyFor with empirical data on tree impacts at three mountain forests in Switzerland. Even though we used model input data with different resolutions at the study sites, RockyFor accurately predicted the spatial distribution of trajectory frequencies at all...

Université de Fribourg

Spatio-temporal variations of rockfall activity into forests results from tree-ring and tree analysis

Stoffel, Markus ; Monbaron, Michel (Dir.) ; Kienholz, Hans (Codir.) ; Strunk, Horst (Codir.) ; Raetzo, Hugo (Codir.)

Thèse de doctorat : Université de Fribourg, 2005 ; Nr. 1480.

Rockfall represents one of the most common geomorphological processes in mountain regions and has extensively been studied in the past. Nonetheless, detailed data on frequencies (how often), volumes (how large), spatial distributions (where) or the seasonality (when) of rockfall activity remain scarce and most of the time fragmentary. Similarly, tree-ring analysis has only exceptionally been used...

Université de Fribourg

Der Fidazer Felssturz von 1939: Analyse & Simulation

Cabernard, Vendelin ; Stoffel, Markus ; Monbaron, Michel

In: Mitteilungen der Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie an der Eidgenössischen Technischen Hochschule Zürich, 2004, vol. 184, p. 1-12

Am 10. April 1939 ging auf dem Gebiet des Dorfes Fidaz (Flims) ein mächtiger Felssturz nieder, 18 Personen fanden den Tod. Die vorliegende Studie hat zum Ziel, diesen Felssturz mit zeitgenössischen Dokumenten neu aufzurollen. Dazu wurden Augenzeugenberichte, Bilder und Karten zur Rekonstruktion des Felssturzes herangezogen und Berechnungen zur mittleren Geschwindigkeit der Sturzmasse...

Université de Fribourg

Assessing the vertical distribution and visibility of rockfall scars in trees

Stoffel, Markus

In: Schweizerische Zeitschrift für Forstwesen, 2005, vol. 156, no. 6, p. 195-199

Rockfall generally consists of individual rocks and boulders moving downslope in a falling, bouncing or rolling motion. As a result, impacts on trees may occur almost anywhere between ground level and several meters above. The present paper therefore focuses on the vertical distribution and the visibility of scars on stem surfaces. Three adult trees from the Altdorfer Bannwald (Altdorf UR,...

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...

Université de Fribourg

Seasonal timing of rockfall activity on a forested slope at Täschgufer (Swiss Alps) – a dendrochronological approach = Saisonale Steinschlagverteilung auf einem bewaldeten Hang im Täschgufer (Schweizer Alpen) – ein dendrochronologischer Ansatz.

Stoffel, Markus ; Lièvre, Igor ; Monbaron, Michel ; Perret, Simone

In: Zeitschrift für Geomorphologie, 2005, vol. 49, no. 1, p. 89-106

Dendrochronology was used to study 25 years of rockfall activity on a forested slope at Täschgufer, Täsch (Swiss Alps). We introduce a new approach by evaluating the initiation of callous tissue and resin duct formation after rockfall occurrence to determine the seasonal timing of events. Results from 270 stem discs of 18 Larix decidua Mill. trees show distinct seasonal differences in...

Université de Fribourg

Analyzing rockfall activity (1600–2002) in a protection forest—a case study using dendrogeomorphology

Stoffel, Markus ; Schneuwly, Dominique M. ; Bollschweiler, Michelle ; Lièvre, Igor ; Delaloye, Reynald ; Myint, Moe ; Monbaron, Michel

In: Geomorphology, 2005, vol. 68(3-4), p. 224

For the first time, dendrogeomorphology has been used to investigate spatial and temporal variations of rockfall activity in a protection forest. We report results of 564 cores from 135 severely injured Larix decidua Mill. trees on the west-facing Täschgufer slope, Swiss Alps. While trees sampled reached an age of 297 years on average, the oldest one attained breast height in AD 1318. For...