Achieving a more realistic assessment of rockfall hazards by coupling three-dimensional process models and field-based tree-ring data

Trappmann, Daniel Gordian; Stoffel, Markus; Corona, Christophe (2014). Achieving a more realistic assessment of rockfall hazards by coupling three-dimensional process models and field-based tree-ring data. Earth surface processes and landforms, 39(14), pp. 1866-1875. Wiley 10.1002/esp.3580

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Sound knowledge of the spatial and temporal patterns of rockfalls is fundamental for the management of this very common hazard in mountain environments. Process-based, three-dimensional simulation models are nowadays capable of reproducing the spatial distribution of rockfall occurrences with reasonable accuracy through the simulation of numerous individual trajectories on highly-resolved digital terrain models. At the same time, however, simulation models typically fail to quantify the ‘real’ frequency of rockfalls (in terms of return intervals). The analysis of impact scars on trees, in contrast, yields real rockfall frequencies, but trees may not be present at the location of interest and rare trajectories may not necessarily be captured due to the limited age of forest stands. In this article, we demonstrate that the coupling of modeling with tree-ring techniques may overcome the limitations inherent to both approaches. Based on the analysis of 64 cells (40 m × 40 m) of a rockfall slope located above a 1631-m long road section in the Swiss Alps, we illustrate results from 488 rockfalls detected in 1260 trees. We illustrate that tree impact data cannot only be used (i) to reconstruct the real frequency of rockfalls for individual cells, but that they also serve (ii) the calibration of the rockfall model Rockyfor3D, as well as (iii) the transformation of simulated trajectories into real frequencies. Calibrated simulation results are in good agreement with real rockfall frequencies and exhibit significant differences in rockfall activity between the cells (zones) along the road section. Real frequencies, expressed as rock passages per meter road section, also enable quantification and direct comparison of the hazard potential between the zones. The contribution provides an approach for hazard zoning procedures that complements traditional methods with a quantification of rockfall frequencies in terms of return intervals through a systematic inclusion of impact records in trees.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Trappmann, Daniel Gordian; Stoffel, Markus and Corona, Christophe

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0197-9337

Publisher:

Wiley

Language:

English

Submitter:

Daniel Gordian Trappmann

Date Deposited:

10 Aug 2015 09:45

Last Modified:

12 Aug 2015 07:06

Publisher DOI:

10.1002/esp.3580

BORIS DOI:

10.7892/boris.70766

URI:

https://boris.unibe.ch/id/eprint/70766

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