Amalie Skålevåg

and 2 more

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.