Effects of fluid ice content and bed wetness on entrainment of debris flows induced by ice avalanches.

This article focuses on the erosion characteristics of debris flows induced by ice avalanches (DFIs), a unique type of glacial debris flow containing ice, water, and soil, commonly occurring in alpine regions. Through flume experiments simulating DFIs with varying ice contents (0%–20%) and bed soil water contents (0%–14%), the study found that erosion depth distribution is spatially asymmetric, with maximum erosion occurring near the upstream end of the erodible bed, and that erosion rate exhibits a parabola-like relationship with bed water content. The presence of ice influences the gravel fraction and collisional stresses within the flow, affecting erosion dynamics and enhancing flow mobility after erosion, though mobility is more closely related to the ice-to-water ratio rather than ice content alone. The study proposes an erosion rate model incorporating both frictional and collisional stresses, validated against experimental data, and highlights that unsaturated bed soils exhibit drained behavior facilitating erosion, whereas saturated soils show undrained behavior that resists erosion. The findings contribute to understanding DFI dynamics and provide a physically based erosion model applicable under varying ice and bed wetness conditions.