Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/nhess-2016-295
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
30 Sep 2016
Review status
This discussion paper is under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Debris flow modeling at Meretschibach and Bondasca catchment, Switzerland: sensitivity testing of field data-based erosion model
Florian Frank1, Brian W. McArdell1, Nicole Oggier2, Patrick Baer3, Marc Christen4, and Andreas Vieli3 1Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, 8903, Switzerland
2wasser/schnee/lawinen, Ingenieurbüro André Burkard AG, Brig-Glis, 3900, Switzerland
3Glaciology, Geomorphodynamics & Geochronology, Department of Geography, University of Zurich, Zurich, 8057, Switzerland
4WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, 7260, Switzerland
Abstract. Debris flow volumes can increase due to the incorporation of sediment into the flow as a consequence of channel-bed erosion along the flow path. This study describes a sensitivity analysis of the recently-introduced RAMMS debris flow entrainment algorithm which is intended to help solve problems related to predicting the runout of debris flows. The entrainment algorithm predicts the depth and rate of erosion as a function of basal shear stress based on an analysis of erosion measurements at the Illgraben catchment, Switzerland (Frank et al., 2015). Starting with a landslide-type initiation in the RAMMS model, the volume of entrained sediment was calculated for recent well-documented debris-flow events at the Bondasca and the Meretschibach catchments, Switzerland. The sensitivity to the initial landslide volume was investigated by systematically varying the initial landslide volume and comparing the resulting debris-flow volume with estimates from the field sites. In both cases, the friction coefficients in the RAMMS runout model were calibrated using the model where the entrainment module was inactivated. The results indicate that the entrainment model predicts plausible erosion volumes in comparison with field data. By including bulking due to entrainment in runout models, more realistic runout patterns are predicted in comparison to starting the model with the entire debris-flow volume (initial landslide plus entrained sediment). In particular, lateral bank overflow – not observed during this event – is prevented when using the sediment entrainment model, even in very steep (≈ 60–65 %) and narrow (4–6 m) torrent channels. Predicted sediment entrainment volumes are sensitive to the initial landslide volume, suggesting that the model may be useful for both reconstruction of historical events as well as the modeling of scenarios as part of a hazard analysis.

Citation: Frank, F., McArdell, B. W., Oggier, N., Baer, P., Christen, M., and Vieli, A.: Debris flow modeling at Meretschibach and Bondasca catchment, Switzerland: sensitivity testing of field data-based erosion model, Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2016-295, in review, 2016.
Florian Frank et al.
Florian Frank et al.
Florian Frank et al.

Viewed

Total article views: 217 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
169 44 4 217 3 5

Views and downloads (calculated since 30 Sep 2016)

Cumulative views and downloads (calculated since 30 Sep 2016)

Viewed (geographical distribution)

Total article views: 217 (including HTML, PDF, and XML)

Thereof 217 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 28 Mar 2017
Publications Copernicus
Download
Short summary
This study describes a sensitivity analysis of the RAMMS debris flow entrainment model which is intended to help solve problems related to predicting the runout of debris flows. The results indicate that the entrainment model predicts plausible erosion volumes in comparison with field data. These eroded volumes are sensitive to the initial landslide volume, suggesting that this tool may be useful for both reconstruction of historical events as well as the modeling of debris flow scenarios.
This study describes a sensitivity analysis of the RAMMS debris flow entrainment model which is...
Share