As avalanches, landslide, debris and pyroclastic flows hurtle down mountain and valley slopes on Earth and other planets, they often entrain bed material along their way. Erosion and deposition of granular material play a key role in the overall dynamics of transportation and emplacement processes of these geophysical flows. Entrainment of the substrate by a flowing mass could either accelerate or decelerate the flow (i.e., increase or decrease its mobility) depending on the nature of the erodible material, the presence of fluid within the flowing and/or erodible layer, as well as on the topography and on the dynamics of the flow. Quantitative aspects of erosion processes have, however, so far been insufficiently studied in the field and in the laboratory as well as in numerical models, in particular doe to the difficulty to perform quantitative in situ measurements of erosion features and to the lack of understanding of the static/flowing transition in granular media. Main questions are what is the role of erosion in the dynamics and emplacement processes of geophysical flows; How does the bedrock topography, the nature (particle size, fluid content, mass, shape…) of the flowing material and/or erodible material, the dynamics of the flow, … affects erosion efficiency.
We propose in this session to gather and confront field observations of geophysical flows (landslides, snow and debris avalanches, pyroclastic flows, sediment transport, …), laboratory experiments, theoretical and numerical modeling of erosion/deposition processes and of the static/flowing transition in granular flows developed both in geophysics and physics.