Abstract
Ongoing climate change and cryospheric degradation are intensifying
sediment transport in cold mountain regions, leading to elevated
sediment loads that adversely impact downstream areas. However, the
influence of freeze-thaw processes on daily catchment-scale sediment
transport in glaciated basins remains poorly understood. Here, we
estimate the effect of freeze-thaw processes on daily suspended sediment
concentrations (SSC) in the Vent-Rofental basin, Austria. Using Bayesian
change-point hierarchical regression, we assess the influence of
streamflow, frozen ground extent, and diurnal freeze-thaw cycles across
three distinct freeze-thaw states: thawing spring, thawed summer, and
freezing autumn. While streamflow is the dominant driver of sediment
transport, its effect is modulated by freeze-thaw processes and
temperature interactions. Frozen ground extent was found to reduce daily
SSC, attributed to a reduction in the sediment contributing area. A
discernible shift in suspended sediment dynamics is observed as the
catchment transitions from frozen to thawed, marked by a change-point
when nearly all (97%) of catchment is thawed. The thawed summer state
exhibited the highest SSC due to elevated glacier melt, while in the
thawing spring state freeze-thaw cycles enhanced sediment transport by
amplifying snowmelt erosion. This study suggests that as glaciers
retreat, snowmelt- and freeze-thaw-driven erosion, in addition to
erosive rainfall, will become increasingly influential in determining
sediment fluxes.