A granular debris flow may grow in size through erosion of its substrate, resulting in an increased hazard through greater mass, speed and runout. Exactly what governs the erosion potential of a particular flow is a matter of some debate, however, with apparently similar conditions producing very different entrainment behaviour. Some theories use an extension of sediment transport models that involve the removal of soil through a shear stress applied by the flow. However, comparison of field and laboratory-scale data suggests that other processes, such as undrained loading of the bed, are also likely to have influence at large scales. Hence properties of the bed need to be considered as well as the characteristics of the flow material. The modelling of erosion processes at laboratory scale is generally limited by the low stresses applied by the soil-water mixture at small scale. Modelling flows in a geotechnical centrifuge overcomes this problem by increasing the g-level, therefore allowing for correct prototype stress levels to be accounted for at small scale. This paper describes the development and use of a model debris flow apparatus on a geotechnical drum centrifuge at ETH in Zurich, Switzerland. Preliminary tests have been undertaken to compare fixed and erodible bed conditions - enabling erosion processes to be examined at prototype stress levels. © 2007 Millpress.