Item: ARE OUR AVALANCHE IMPACT PRESSURE EQUATIONS FIT FOR A WARMING CLIMATE? - INSIGHTS FROM 3D AVALANCHE MODELING
-
-
Title: ARE OUR AVALANCHE IMPACT PRESSURE EQUATIONS FIT FOR A WARMING CLIMATE? - INSIGHTS FROM 3D AVALANCHE MODELING
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Michael J. Kohler [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland ]
- Johan Gaume [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ ETH Zurich, Switzerland ] [ Climate Change, Extremes and Natural Hazards in Alpine Regions Research Centre CERC, Davos, Switzerland ]
- Betty Sovilla [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
Date: 2024-09-23
Abstract: In densely populated mountain regions, snow avalanches are among the main natural hazards and have long been a threat to settlements and critical infrastructure. Yet over the past decades, avalanche fatalities on roads and in settlements have been reduced through extensive avalanche hazard assessment and mitigation measures. In the protection scheme, fast dry-snow avalanches have long been considered the most destructive and thus the determining avalanches. In this case, impact pressure depends primarily on flow velocity, which is commonly obtained from depth-averaged avalanche simulations in engineering practice. With a warming climate, however, slower wet-snow avalanches are becoming more frequent. The impact pressure of these avalanches depends more on flow height and rheological properties of snow, such as friction, cohesion, and compressibility. In the midst of these changing conditions, current impact pressure calculation procedures involving numerical models based on depth-averaged mass and momentum balance equations struggle to capture the complex rheological behavior of snow and three-dimensional avalanche-obstacle interaction effects. We argue that a paradigm shift is needed if we are to meet the challenges posed by wet-snow avalanches. To that end, we propose a highly efficient 3D model based on the Material Point Method (MPM). Through its continuum formulation, it allows for the incorporation of established elastoplastic constitutive models and naturally handles collisions and fractures in a large deformation framework without mesh distortion problems. We demonstrate the relevance and the potential of this modeling approach by simulating key avalanche processes observed at the Vallée de la Sionne avalanche test site. Furthermore, we quantitatively compare calculated impact pressure magnitude and distribution to measurements to show the accuracy of our approach and address the consequences of common modeling assumptions in avalanche engineering, such as neglecting snow compressibility. This work aims to highlight the complex rheological composition of avalanche impact pressure and demonstrates the importance of a more fundamental and general impact pressure assessment in light of climate change.
Object ID: ISSW2024_O2.4.pdf
Language of Article: English
Presenter(s): Michael J. Kohler
Keywords: climate change, impact pressure, wet-snow, dense, avalanche dynamics, modeling, Material Point Method
Page Number(s): 299 - 305
-