Unveiling Hidden Heterogeneity: UAV-borne GPR for Investigating Alpine Snowpack Variability

Avalanche risk assessment critically depends on understanding snowpack conditions. Conventional methods, such as weather forecasts, field observations, and snow pits, provide valuable information but are limited in their ability to capture the high spatial variability often observed within the snowpack. Geophysical near-surface methods can help unveil spatial variabilities within the snowpack. This study investigates the use of unmanned aerial vehicles (UAVs) equipped with ground-penetrating radar (GPR) to characterize snowpack heterogeneity at high spatial resolution, previously unattainable using conventional methods. Our study found a high correlation (R²=0.93, r=0.97) between snow depth measurements obtained from UAV-borne GPR and conventional probe measurements, indicating a strong accuracy of the GPR method for assessing snow depth. This suggests that UAV-borne GPR can effectively and reliably measure snow depth. Data collected from multiple alpine sites in the Austrian Alps revealed pronounced spatial variability within the snowpack over short distances. The analysis unveiled considerable snow depth variability with values ranging from < 1 m to > 4 m within our largest study site (~ 0.07 km²) at Stubai Glacier, Tyrol, Austria. We furthermore observed a high degree of internal snowpack variability within short distances. These findings emphasize the importance of considering spatial variability in avalanche formation and highlight the potential of UAV-borne GPR to provide valuable insights beyond the limitations of traditional methods. The system employed in this study utilizes readily available components, making it a potentially valuable tool for both researchers and practitioners, potentially complementing conventional methods for more comprehensive snowpack analysis and avalanche mitigation.