Effects of debris-flow and bed composition on erosion and entrainment

Erosion and entrainment of material by debris flows determine debris-flow volume growth therefore hazard potential. Recent advances in field, laboratory, modelling studies have distilled two driving forces behind erosion; impact shear forces. A third factor influencing the (relative) importance these is viscosity abundance interstitial fluid flow bed. However, how erosion depend on composition itself bed remains unclear. Here, we present results small-scale flume experiments with a loosely packed erodible that highlight far-reaching effects processes magnitude. We quantify gravel, clay, solid fraction erosion. In addition, water clay content unconsolidated flow. show increases linearly when gravel increased, which linked to an increase both find erosion, related forces, are non-linearly impacted those For bed, optimum exists around specific percentage does not directly relate either or When and/or becomes largest supersaturated conditions occur. These unrelated magnitude This shows affect affecting transfer pore pressures from can conclude dictate most cases but their significantly altered means effectivity pressure The latter highly influenced