Investigating Avalanche Interaction with Defence Structures using unmanned Aerial System Photogrammetry

116-120

Artikel aus einem Buch

200204827

ISSW2018 - General Topic: Protection measures: Risk management and engineering solutions ; O2.3 (2018) , 116-120
ISSW2018: international snow science workshop: a merging of theory and practice - Abstracts ; O2.3 (2018) 

Unmanned aerial system photogrammetry (UAS-P) is increasingly becoming a commonplace tool to generate orthophotos and measure surface elevation with ground sampling distances in the centimetre-range. In this contribution, we present results from a UAS-P mission to map an avalanche event, which occurred near the city Innsbruck in Western Austria. The main objective of the campaign was to document avalanche extent and volume, as well as investigate avalanche interaction with different types of defence structures, located in the track and runout area. The results of this case study showed that in total, 70.000 m³ of snow and debris were deposited. The highest deposition depths (> 5 m) were reached where a rocky outcrop reduced the width of the track from 40 to 15 m, and near the deposition terminus, where the avalanche impacted several concrete wedges, catching and deflection
dams. A comparison between slope angles and deposition depths showed, that the main part of the deposition volume originated from medium deposition depths (2.1-2.2 m) at slope angles between 15-25°, which covered ~62% of the total deposition area. The combination of orthophoto interpretation and spatial deposition analysis revealed that terrain variations such as channelisation and defence structures locally dominate the deposition pattern. Knowledge of these local effects is of major importance to understand the interaction of avalanches with defence structures and improve their design.
KEYWORDS: Snow depth distribution, mitigation measures, unmanned aerial vehicle