New findings on the seasonal behavior of volume concentrations of radon in the vicinity of the dump site No. 15, Brod u Pribrami

Interesting results were obtained by long-term measurements of radon concentrations with TSR 4M and 4S probes at stationary 8-9 positions, covering both the heel and crown of the slope. These measurements were supplemented by a study of flow and temperature conditions, especially at the foot of the slope, where temperatures in the summer fell below freezing in some places. A 24-hour measurement campaign in the fall of 2021 using 33 continuous radon monitors aimed to clarify the dynamics of the avalanche and the preferential access routes of radon from the avalanche towards the village of Brod. The results of these measurements provide an insight into the dynamics of the avalanche in the period when the air temperatures outside the avalanche do not fall below the expected temperature in the body of the avalanche. The study of avalanche behavior in the winter months also yielded interesting findings, both by monitoring long-term series of radon concentrations and their influence on meteorological parameters, and also by using UAVs and on-the-go thermal imaging to identify and subsequently monitor places with intense avalanche gas leakage, so-called hotspots, which are characteristic high radon concentrations and temperatures around 9-10 grad C. The presented results are a good basis for the verification of the prepared model of the dynamics of a landslide as a debris field. (authors)