Reconstructing the Snow Avalanche of Coll de Pal 2018 (SE Pyrenees)

Abstract

Developments in mountain areas prone to natural hazards produce undesired impacts and damages. Thus, disaster assessment is mandatory to understand the physics of dangerous events and to make decisions to prevent hazardous situations. This work focusses on the practical implementation of methods and tools to assess a snow avalanche that affected a road at the Coll de Pal in 2018 (SE Pyrenees). This is a quite common situation in mountain roads and the assessment has to focus specially in the avalanche–road interaction, on the return periods considered and on the dynamics of the phenomena. This assessment presents the field recognition, snow and weather characterization and numerical modelling of the avalanche. Field campaigns revealed evidences of the avalanche triggering, runout trajectory and general behavior. An unstable situation of the snowpack due to a relatively large snowfall fallen some days before over a previous snowpack with weak layers, caused the avalanche triggering when an additional load was added by a strong wind-drift episode. A medium size (<2500 m3) soft slab avalanche, corresponding to a return period of 15–20 years, occurred and crossed the road of the Coll de Pal pass. The event was reproduced numerically by means of the 2D-SWE based numerical tool Iber aiming to analyze the avalanche behavior. Results of the simulation corresponded with the observations (runout trajectory and snow deposit); thus, relevant information about the avalanche dynamics could be obtained. Identified differences probably come from the terrain elevation data, which represent “snow free” topography and do not consider the snowpack on the terrain.

GIS-Based Spatial Modeling of Snow Avalanches Using Analytic Hierarchy Process. A Case Study of the Šar Mountains, Serbia

“…For the purposes of judging pairwise comparisons, a numerical scale of 9 degrees is used, according to values from 1 (equal importance) to 9 (extreme importance). AHP scale: 1, equal importance; 3, moderate importance; 5, strong importance; 7, very strong importance; and 9, extreme importance (2,4,6,8 values in-between) [56,57].…”

“…Snow avalanche is a natural disaster caused by large snow masses sliding down mountain slopes under the influence of gravity [1][2][3]. This is a typical phenomenon for mountainous regions worldwide [4][5][6]. In addition to snow, avalanches often contain other materials (rock debris, soil, plants) which are transported and accumulated in the lower areas.…”

“…Košová et al [5] performed an in-depth analysis of the snow avalanche risk within the Král'ova Hol'a area (Low Tatra Mountains in Slovakia) by modeling the trigger areas and simulating avalanche movements and their maximum impact by using GIS and the RAMMS simulation model. Sanz-Ramos et al [6] reconstructed the snow avalanches of the Coll de Pal area in SE Pyrenees range by utilizing approaches such as field recognition, snow and weather characterization and numerical modeling. Bühler et al [24] analyzed avalanche data from three different ski resorts in the vicinity of Davos, Switzerland by using an object-based approach for largescale hazard indication mapping thus opening the door for large-scale avalanche hazard indication mapping in all regions where high-quality and high-resolution digital terrain models and snow data are available.…”

Interpreting the Manning Roughness Coefficient in Overland Flow Simulations with Coupled Hydrological-Hydraulic Distributed Models

“…For all three case studies, the coupled hydrological-hydraulic distributed modelling was performed using Iber [47] version 3.1, a 2D free-surface numerical modelling initially developed for hydrodynamic and sediment transport purposes [47][48][49]. Currently, it includes several calculation modules [50][51][52][53][54][55][56][57], in particular, one for the simulation of the hydrological processes of rainfall-runoff transformation-including infiltration lossesfully integrated with the overland flow propagation [25,58,59].…”

Influence of snow and meteorological conditions on snow‐avalanche deposit volumes and consequences for road‐network vulnerability

“…Snow avalanches create a menace for people and settlements and create road obstructions (Eckert et al, 2018; Leone et al, 2014; Rheinberger et al, 2009; Sanz‐Ramos et al, 2021). Avalanche deposits cause road obstructions, and the volume of snow on the road directly determines the time of disruption and possible associated damages to road infrastructure (Bründl et al, 2004).…”