Farin M. auteur aut IRD Mangeney A. auteur aut IRD Roche Olivier auteur aut IRD text journalArticle eng text/pdf born digital access Entrainment of underlying debris by geophysical flows can significantly increase the flow deposit extent. To study this phenomenon, analog laboratory experiments have been conducted on granular column collapse over an inclined channel with and without an erodible bed made of similar granular material. Results show that for slope angles below a critical value (c), between 10 degrees and 16 degrees, the run out distance r(f) depends only on the initial column height h(0) and is unaffected by the presence of an erodible bed. On steeper slopes, the flow dynamics change fundamentally, with a slow propagation phase developing after flow front deceleration, significantly extending the flow duration. This phase has characteristics similar to those of steady uniform flows. Its duration increases with increasing slope angle, column volume, column inclination with respect to the slope and channel width, decreasing column aspect ratio (height over length), and in the presence of an erodible bed. It is independent, however, of the maximum front velocity. The increase in the duration of the slow propagation phase has a crucial effect on flow dynamics and deposition. Over a rigid bed, the development of this phase leads to run out distances r(f) that depend on both the initial column height h(0) and length r(0). Over an erodible bed, as the duration of the slow propagation phase increases, the duration of bed excavation increases, leading to a greater increase in the run out distance compared with that over a rigid bed (up to 50%). This effect is even more pronounced as bed compaction decreases. specialized dynamic erosion deposition avalanche 066 119 3 504-532 2014 2169-9003 https://www.documentation.ird.fr/hor/fdi:010061955 10.1002/2013jf002750 2169-9003 [F B010061955] https://www.documentation.ird.fr/hor/fdi:010061955 https://www.documentation.ird.fr/intranet/publi/2014/05/010061955.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2014-05-28 2017-08-23 fdi:010061955 fre