Modelling cascading processes with MPM: Effects of alpine mass movements on lake outburst floods
The number of Alpine reservoirs or lakes threatened by mass gravitational flows such as snow avalanches, landslides, debris flows or rock avalanches may increase with the occurrence of extreme events in the future. Impulse waves caused by their impacts on reservoirs and lakes pose a considerable risk to the nearest tourism infrastructure, or inhabited areas.
Modeling these complex interactions requires appropriate approaches as well as potential input scenarios. One of the major impediments in modeling the interaction between gravitational mass movements and reservoir lakes is the numerical description of phase changes in transient dynamic flows. The ability to simulate the coexistence of different material types and processes such as fracturing and multiphase mixing or impact, e.g. with water, is essential to reproduce the proper dynamics of complex process chains. A further problem is the modelling of the initial interaction between gravitational mass flows and water reservoirs, which should ideally be solved by fully three-dimensional methods.
These problems can be solved using the Material Point Method (MPM). Over the past years a 3D Material Point Method (MPM) model coupled with finite strain elastoplasticity has been developed to simulate the release and flow of snow avalanches at the slope scale in three dimensions including different flow regimes. More recently, the model was extended to include multi-phase solid-fluid interactions and different constitutive models (rock, ice, water) calibrated based on laboratory experiments. These new developments allowed preliminary simulations of tsunamis induced by glacier calving as well as the dynamics of cascading alpine mass movements like the 1963 Vajont landslide and lake outburst or the 2017 Piz-Cengalo process chain.
In this project we want take advantage of these new developments and use the 3D MPM model as a full-scale numerical laboratory to simulate relevant and extreme rock and snow avalanche input scenarios associated with the instability of the "Spitze Stei" (Kanderberg, BE), and the Dorfberg (Davos, GR) avalanche and their interaction with the Öschinen and Davos lakes to quantify the tsunami and outburst flows, which may pose a significant risk to the tourism infrastructure and may endanger the inhabited areas of Kandersteg and Davos.
Video 1: MPM simulation of the Vajont landslide and outburst flood with 20 million particles (Cicoira et al. 2021). The solid material is modeled using a Drucker-Prager elasto-plastic material. The model allowed to reproduce very well the observed run-out, the maximum water level after the landslide and the water volume overtopping the dam crest.
Video 2: MPM simulation of a large rock avalanche occurred shortly after midnight on March 19 2019 on Flüela Wisshorn which then triggered a snow avalanche (Cicoira et al. 2021).
Cicoira, A., Blatny, L., Li, X., Troilo, F., Kenner, R., & Gaume, J. (2021). A Material Point Method for Alpine Mass Movements (No. EGU21-5258). Copernicus Meetings.