The GEOGRAF project is a research project undertaken in the framework of a Marie Curie Intra-European fellowship (Grant 297843)

Summary

The flow of dry granular material is a key Earth surface process, responsible for landscape evolution and naturally-hazardous rockslides and debris flows. Dry granular materials can be mobilized due to tectonic, seismic or climatic forcing, and form an important natural hazard.
Dry debris flows can be triggered by various mechanisms, involve materials from micron to metre scale, and flow on a wide range of topography, yet they share a common characteristic: they are highly mobile, and travel horizontal distances many times their initial height, thus enhancing the risk to vulnerable populations. Explaining this high mobility of natural granular flows has proven a long-lasting scientific challenge, specifically in the case of dry debris flows: despite the absence of any interstitial fluid (water, melted snow etc), the crushed rock, soils and debris forming the core of the flowing material show the ability to travel and spread extensively that remains unexplained by existing frictional or dissipative descriptions of flow dynamics and emplacement. The high mobility on low slopes, steep and well-defined deposit fronts, and dependence of the flow runout on its volume have long been recognised as being inconsistent with classical Coulomb friction. In this context, the role of grain size and segregation, as well as the role of the underlying topography on the flow mobility deserves specific attention.
The aim of the GEOGRAF project is to address both aspects, combining laboratory experiments and numerical simulations, and discrete and continuum approaches.