Snow Stratigraphy Measurements With UWB Radar

Abstract

The focus of this thesis is to find and verify a non-invasive method to determine the layer distribution (stratigraphy) in snowpacks, which might aid avalanche risk assessment. Slab avalanches release due to failure and collapse in a weak snow layer. Determining the spatial distribution and depth of weak layers in avalanche starting zones is a high-risk task. Moreover, by manually digging snow pits, the occurrence of a weak layer can only be identified on a pit scale. We, therefore, propose a technical solution to this problem by mounting an ultra wideband radar system onto an unmanned aerial vehicle to obtain information about weak layers over a larger area and improve safety for avalanche professionals. During 2016, we have operated the radar system via a stationary platform 1 m above the snow, along 4.2 m long transects. For verification, we dug a full snowpit and used snow measurement probes (Avatech SP2 and Toikka SnowFork) to measure snow depth, liquid water content and density, as well as snow stratigraphy. Results show an average correlation between radar and in situ measurements of 0.97 and RMS error of 2.48 cm when extracting the most prominent transitions in the snow. The method developed in this thesis is tested on different types of snow. Additionally, the radar system is tested as payload on an unmanned aerial vehicle. Future work includes further development of the radar system and airborne measurements on snowpacks.