Multi-Temporal UAV Monitoring of the Rutor Glacier: Five Years of High-Resolution Change Analysis

Climate change is strongly impacting the Alpine environment, increasing hazardous phenomena and rapidly changing this sensitive landscape. Repeated monitoring helps to understand the evolution of the lower part of the glacier, water dynamics, and geomorphological changes. For these reasons, Unmanned Aerial Vehicles (UAVs) are reliable tools for investigating small-scale evolution in complex environments.

This work presents the results of a five-year monitoring program carried out by the Geomatics GlacierLab research group of Politecnico di Torino on the Rutor Glacier, located in the Graian Alps (Aosta Valley, Italy), where UAV photogrammetric surveys were conducted every summer from 2021 to 2025. Several logistical challenges had to be overcome due to the limited battery endurance of the UAVs, weather conditions, and the fact that the study area is accessible only on foot. Over the years, several survey campaigns were carried out using DJI Phantom 4 to establish and survey a network of Ground Control Points (GCPs) and Check Points (CPs) supporting the drone flights. Furthermore, the lack of mobile network coverage required the use of a local DJI D-RTK 2 Mobile Station to provide RTK corrections during the field surveys.

The data processing workflow allowed the generation of high-resolution orthophotos and Digital Surface Models (DSMs), enabling comparisons between successive years. The adoption of a consistent acquisition and processing workflow ensured the reliability and comparability of the multi-temporal analysis. These products make it possible to quantify glacier surface elevation changes, estimate ice volume loss, and analyse frontal retreat.

The results highlight the importance of systematic UAV monitoring for supporting long-term glacier change assessment and the analysis of geomorphological modifications while providing valuable information to support the activities of the Regional Environmental Protection Agency (ARPA).