Modelling wet snow avalanche runout to assess road safety at a high-altitude mine in the central Andes

Abstract

Abstract. Mining activities in cold regions are vulnerable to snow avalanches. Unlike operational facilities, which can be constructed in secure locations outside the reach of avalanches, access roads are often susceptible to being cut, leading to mine closures and significant financial losses. In this paper we discuss the application of avalanche runout modelling to predict the operational risk to mining roads, a long-standing problem for mines in high-altitude, snowy regions. We study the 35 km long road located in the "Cajón del rio Blanco" valley in the central Andes, which is operated by the Codelco Andina copper mine. In winter and early spring, this road is threatened by over 100 avalanche paths. If the release and snow cover conditions can be accurately specified, we find that avalanche dynamics modelling is able to represent runout, and safe traffic zones can be identified. We apply a detailed, physics-based snow cover model to calculate snow temperature, density and moisture content in three-dimensional terrain. This information is used to determine the initial and boundary conditions of the avalanche dynamics model. Of particular importance is the assessment of the current snow conditions along the avalanche tracks, which define the mass and thermal energy entrainment rates and therefore the possibility of avalanche growth and long runout distances.

Automated snow avalanche release area delineation – validation of existing algorithms and proposition of a new object-based approach for large scale hazard indication mapping

“…On the long term, the current work could enable the coupling of terrain information, meteorological data, snow pack simulations and numerical avalanche simulations to achieve near real time hazard assessment over large areas as proposed by (Vera Valero et al, 2016) and . However, the required input information in sufficient quality and 15 resolution necessary for such a coupled system is very hard to get.…”

“…We constrain the reference dataset to slab avalanches and exclude loose snow avalanches, which can start at point locations also in very steep terrain but do not mobilize masses that could be dangerous for people and infrastructure in the Alps. However, such avalanches can become more dangerous in other regions such as the Chilean Andes (Vera Valero et al, 2016).…”

Modeling the influence of snowcover temperature and water content on wet snow avalanche runout

“…Wet snow avalanche modeling necessitates the simulation of four physical processes : One model that fulfills these requirements was developed by Vera et al (2015Vera et al ( , 2016. In this model, the flow of the dense avalanche core (subscript Φ) is described by nine independent state variables:…”

“…To determine the initial temperature and moisture content of the snowcover requires an accurate 225 modeling of the surface energy fluxes (sensible and latent heat exchanges, incoming short and longwave radiation) which are influenced by the slope exposition. We account for exposition effects on surface energy fluxes using the virtual slope concept proposed by Lehning et al (2008), which was found to provide accurate slope simulations that correspond with wet snow avalanche activity, Vera et al, 2016). We obtain snowcover layering, temperature, density and…”

“…These parameters were kept constant for all 12 case studies as in . The fluidization parameter α (see ; Vera et al (2016)), was fixed to a pre-determined value based on the terrain characteristics for each avalanche path. Once this parameter was fixed it was not tuned for the remaining set of simulations.…”