Avalanche hazard mapping over large undocumented areas

Abstract

An innovative methodology to perform avalanche hazard mapping over large undocumented areas is herewith presented and discussed. The method combines GIS tools, computational routines, and statistical analysis in order to provide a ''semi-automatic'' definition of areas potentially affected by avalanche release and motion. The method includes two main modules. The first module is used to define zones of potential avalanche release, based on the consolidated relations on slope, morphology, and vegetation. For each of the identified zones of potential release, a second module, named Avalanche Flow and Run-out Algorithm (AFRA), provides an automatic definition of the areas potentially affected by avalanche motion and run-out. The definition is generated by a specifically implemented ''flow-routing algorithm'' which allows for the determination of flow behaviour in the track and in the run-out zone. In order to estimate the avalanche outline in the run-out zone, AFRA uses a ''run-out cone'', which is a 3D projection of the angle of reach a. The a-value is evaluated by statistical analysis of historical data regarding extreme avalanches. Pre-and post-processing of the AFRA input/output data is done in an open source GIS environment (GRASS GIS). The method requires only a digital terrain model and an indication of the areas covered by forest as input parameters. The procedure, which allows rapid mapping of large areas, does not in principle require any site-specific historical information. Furthermore, it has proven to be effective in all cases where a preliminary cost-efficient analysis of the territories potentially affected by snow avalanche was needed.

Potential slab avalanche release area identification from estimated winter terrain: a multi-scale, fuzzy logic approach

“…Terrain parameters DTM resolution Classification approach Andres and Cía (2012) slope, plan curvature 5 m (from 1 : 25 000 m map) binary Barbolini et al (2011) slope, plan curvature 10 m binary Bühler et al (2012) slope, plan curvature, roughness 5 m binary Cia et al (2014) slope, plan curvature 5 m (from 1 : 25 000 m map) binary Ghinoi and Chung (2005) slope, aspect, elevation, curvature, 20 m continuous distance to ridge Gruber and Sardemann (2003) slope, plan curvature, distance to ridge 25, 50 m for curvature binary Maggioni and Gruber (2003) slope, aspect, plan curvature, distance to ridge 25, 50 m for curvature binary Pistocchi and Notarnicola (2013) slope, aspect, elevation, profile curvature, 10 m continuous distance to ridge, topographic wetness index or the elevation of isotherms (Cia et al, 2014), or they introduce a qualitative roughness measure derived from aerial photographs (Ghinoi and Chung, 2005). An overview of the existing approaches and their corresponding terrain parameters is shown in Table 1.…”

Potential slab avalanche release area identification from estimated winter terrain: a multi-scale, fuzzy logic approach

“…Terrain parameters DTM resolution Classification approach Andres and Cía (2012) slope, plan curvature 5 m (from 1 : 25 000 m map) binary Barbolini et al (2011) slope, plan curvature 10 m binary Bühler et al (2012) slope, plan curvature, roughness 5 m binary Cia et al (2014) slope, plan curvature 5 m (from 1 : 25 000 m map) binary Ghinoi and Chung (2005) slope, aspect, elevation, curvature, 20 m continuous distance to ridge Gruber and Sardemann (2003) slope, plan curvature, distance to ridge 25, 50 m for curvature binary Maggioni and Gruber (2003) slope, aspect, plan curvature, distance to ridge 25, 50 m for curvature binary Pistocchi and Notarnicola (2013) slope, aspect, elevation, profile curvature, 10 m continuous distance to ridge, topographic wetness index or the elevation of isotherms (Cia et al, 2014), or they introduce a qualitative roughness measure derived from aerial photographs (Ghinoi and Chung, 2005). An overview of the existing approaches and their corresponding terrain parameters is shown in Table 1.…”

The MultiRISK platform: The technical concept and application of a regional-scale multihazard exposure analysis tool

“…Maggioni and Gruber (2003) developed a methodology for the determination of potential release areas primarily based on topographic parameters that was simplified by Barbolini et al (2011). This methodology applies the following criteria: For avalanche initiation, a certain minimum slope angle is necessary to enable the movement; however, very steep slopes will not accumulate enough snow for avalanche formation.…”

“…Mc Clung and Lied (1987) investigated 212 avalanches and found a range of 18-49°with a mean of 30.3°. Barbolini et al (2011) calculated an average slope angle of 27.3°with a standard deviation of 5.1°for an inventory of 2004 extreme avalanches in the Italian mountain range (Alps and Apennines). The lowest detected angle of 14°was adopted for this study.…”