Spatial and temporal evolution of an experimental debris flow, exhibiting coupled fluid and particulate phases

The internal behaviour of debris flows provides fundamental insight into the mechanics responsible for their motion. We provide robust velocity data within a small-scale experimental debris flow, consisting of the instantaneous release of a granular material along a rectangular flume, inclined at $$31^{\circ }$$ . The results show a unique layered transition from a collisional, turbulent front to a non-fluctuating viscous-type flow body, exhibiting strong fluid-particulate coupling. This is the first time that the internal dynamics have been documented within the full architecture of a developing experimental debris flow, from the head to the tail.