Assessing the paraglacial evolution magnitude affecting proglacial areas through multi-temporal digital models and historical archives

Proglacial areas are environments undergoing rapid evolution due to climate change, featured by the transition from a glacial to a non-glacial regime (i.e., paraglacial stage). This study uses a combination of historical analyses, remote sensing, and field surveys to investigate the evolution of the proglacial areas of the Aurona and Leone Glaciers (north-western Italian Alps) over the last 150 years. Historical data provided insights into glacier retreat trends, proglacial areas widening, and the formation and evolution of notable elements such as proglacial lakes. Remote sensing techniques such as Structure-from-Motion (SfM) and Digital Photogrammetry enabled the creation of digital models for the 2000–2023 period. They were used to quantify geomorphological changes through DEM differencing and cloud-to-cloud comparisons. The illustrated results reveal a significant and continuous retreat of the Aurona glacier, resulting in substantial proglacial area expansion and complex paraglacial adaptations, including subsidence related to dead ice melting, water runoff and debris flows affecting the inner moraine flanks. Even if receding too, the Leone glacier shows the relevant presence of buried ice, leading to the development of ephemeral lakes and tracks of downvalley flows. The comparison of DEMs and 3D point clouds highlighted differential elevation and volume changes, with the Leone proglacial area showing the higher values and potentially higher sediment load if compared to Aurona. This study underlines the importance of multi-temporal remote sensing in capturing the dynamic evolution of proglacial areas and provides a framework for assessing and quantifying geomorphological changes in proglacial areas driven by climate-induced glacier retreat.