Reconstructing glacier-controlled sediment connectivity through time: Late Quaternary landscape evolution in the southeastern Alps

Sediment (dis)connectivity is a fundamental concept for the understanding of landscape evolution and sediment fluxes, yet its long-term variability across contrasting climatic and glacial conditions remains poorly constrained. In particular, glaciers are commonly treated as purely erosional agents, while their role in structuring sediment pathways and storage through time is still underexplored.

In this study, we investigate the evolution of sediment connectivity during key phases of Late Quaternary landscape development, from the pre-Last Glacial Maximum (>30 ka), the Late Late Glacial (~14.7–11.7 ka), to the present. The Terragnolo Valley, an Alpine catchment in the southeastern European Alps, provides an ideal natural laboratory, having been repeatedly shaped by glaciations involving both a local glaciares and the Adige trunk glacier (>1000 m thick), resulting in an exceptional abundance of glacial and proglacial deposits.

We adopt a methodological framework that explicitly considers glaciers and associated sedimentary bodies as dynamic controls on sediment (dis)connectivity within a watershed. High-resolution palaeotopographies (2 m DTMs) are reconstructed for each target time slice by integrating detailed geomorphological mapping, stratigraphic constraints, and terrain modelling techniques. Sediment connectivity is quantified using the Index of Connectivity (IC; Borselli et al., 2008; Cavalli et al., 2013), accounting for time-dependent forcing factors such as ice extent and evolving topographic configuration.

The IC-based analysis is complemented by field-based geomorphological observations, with particular attention to the identification of buffers and barriers following the conceptual framework of Fryirs et al. (2007). With this approach, we aim to reconstruct past sediment pathways and to explore how glacial dynamics promoted sediment storage, fragmentation of connectivity, or, conversely, efficient sediment transfer. Connectivity under modern conditions is computed using the SedInConnect software (Crema and Cavalli, 2018while specific topographic reconstruction enable its application to palaeolandscapes.

Our results aim to elucidate how glacier-driven landscape reorganization controlled sediment distribution and led to the development of disproportionate sediment accumulations in specific sectors of the catchment. By reconstructing sediment connectivity through multiple glacial–interglacial transitions, this study provides new insights into the long-term controls on sediment fluxes in Alpine environments and offers a framework for contextualizing present-day sediment dynamics within their Quaternary context.