Item: Where to dig? – on optimizing sampling strategy
Title: Where to dig? – on optimizing sampling strategy
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Jürg Schweizer and Sascha Bellaire, WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
Abstract: Snow slope stability evaluation is often based on a single test location within a slope. However, we know that snow cover properties and stability may vary at the slope scale. Reliably estimating the slope scale variability requires many samples, probably up to 100. As this is unpractical, it has been proposed to do at least two tests – about 10 m apart – on a given slope. In addition, if small column stability tests are used (such as the compression test), it seems reasonable to perform two tests at each of the two locations. Differences between the two tests at one location allow one to assess the small scale variability (and/or the test uncertainty), whereas differences between the pairs at different locations may hint at the slope scale variability. We analysed 22 slopes each with four pairs of stability tests. In 6173% of the cases the two stability tests at a specific location provided consistent results. Comparing the different sampling locations on a given slope (!10 m apart) showed that in many cases (5975%) differences between sampling locations were rather small. Based on our analysis, we suggest an interpretation scheme and an adjusted sampling procedure.
Keywords: snow avalanche release, snow stability evaluation, snow stability test
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