Debris flows and floods in gullies and torrents south of the Simplon Pass: past activity and (meteorological) triggers

South of the Simplon Pass, several torrents and gullies produced major debris flows over the last 15 years. In addition, considerable amounts of sediments have been mobilized from and transferred into the Krummbach, Laggina and Grosses Wasser torrents. In the framework of the RUFINE project, some 108 European larch (Larix decidua Mill.) and Norway spruce (Picea abies (L.) Karst.) trees have been sampled along the embankments of the Laggina (Laggin Valley) and the Grosses Wasser torrents (Zwischbergen Valley). In addition, 107 increment cores have been gathered on the cone of two minor tributaries (Rots Chi and Feergraben), as they yield considerable amounts of material into the Grosses Wasser and Laggina torrents. Following the identification of past events from the tree-ring series, dendrogeomorphological results will be compared with discharge records of the Krummbach torrent and with meteorological data of neighboring weather stations (Binn, Brig, Saas-Fee, Simplon-Dorf) so as to understand triggering mechanisms and thresholds for the release of events. First results can be expected for the end of 2007.


Contractors: Swiss Federal Office for the Environment (FOEN), Cantonal Department for Traffic, Construction and Environment (Canton of Valais)

Project duration: July 2006 – December 2007

Contact: Markus Stoffel


Bollschweiler M., Stoffel M., Schneuwly D.M., Bourqui K., (2008): Traumatic resin ducts in Larix decidua stems impacted by debris flows. Tree Physiology 28: 255–263. [PDF]

Bollschweiler, M., Stoffel, M., Schneuwly, D. M., Bourqui, K. (2008): Tangential rows of traumatic resin ducts in Larix decidua trees impacted by debris flows. Geophysical Research Abstract 10: 01802 [PDF]