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R. Sailer, E. Bollmann, C. Briese, A. Fischer, C. Klug, K. Krainer, N. Pfeifer, M. Schümberg, J. Stötter:
"The quantification of changes in the alpine cryosphere and periglacial environment based on ALS data";
Talk: Managing Alpine Future II, Innsbruck; 2011-11-21 - 2011-11-23.

Creeping mountain permafrost, best represented by rockglaciers, is basically defined by its
thermal conditions, material properties and its internal deformation. Rockglaciers typically
creep at surface velocities of a few centimetres up to a few meters per year. In recent years,
high resolution remote sensing methods gained attention for measuring surface deformations
of rock glaciers. Optimal investigations of rockglacier creep requires: (i) area-wide surface
and detailed information to account for 3D effects, (ii) in view of the low deformation rates,
the application of precise high-resolution mapping techniques, and (iii) long-term monitoring
for documentation of slow temporal changes at a sufficient level of accuracy.
Within the project C4AUSTRIA (Climate Change Consequences on the Cryosphere - funded
by Austrian Climate Research Programme (ACRP), Österreichischer Klima- und Energiefonds)
Airborne Laserscanning (ALS) data are applied to detect, quantify and analyse deformation
rates of rockglaciers and adjacent periglacial elements, situated in four cirques in the Ötztal
and Stubai Alps: Schrankar, Reichenkar, Hochebenkar and Ölgrube. Beside the base ALS data
(2006) two ALS campaigns are scheduled in C4AUSTRIA. One of them was carried out in
2009, the second will follow in autumn 2011. In autumn 2010 an additional ALS campaign
was realized within an alpS Centre for Climate Change Adaptation Technologies project
MUSICALS (Multiscale Snow/Icemelt Discharge Simulation into Alpine Reservoir). Thus, at
the moment at least three (a fourth campaign is available for the Reichenkar rock glacier)
ALS data sets can be used to quantify and analyse changes in the cryosphere and the adjacent
periglacial environment. Analogue aerial stereoscopic images from 1953, 1969, 1973, 1977,
1990 and 1997 and subsequent products are added to extend the time series. As a first, the
multi-temporal ALS and photogrammetry digital terrain models (DTM) are subtracted from
each other to quantify volume changes of cryosphere elements (e.g. rockglaciers) and periglacial
phenomenon (e.g. dead ice). Further, the respective ortho-images or the shaded reliefs
(gained from photogrammetric aerial image processing as well as the ALS DTM) are used to
calculate surface velocities of selected rockglaciers over the entire period from 1953 to 2010.
If any (in general field observations in rockglacier areas started later than aerial photography),
in-situ data (e.g. dGPS) are used to validate the volume changes and displacement
rates, gained from ALS and photogrammetric information. Considering measurement errors,
we can summarize: i) that the use and combination of photogrammetry and ALS allows high
quality area-wide monitoring and quantification of rockglacier surface kinetics, (ii) that
the geometric accuracy of our input data and applied methods is appropriate to calculate
rockglacier surface velocities with low deformation rates and even low volume changes, (iii)
that the combination of digital photogrammetry and ALS is a promising tool for a long term
monitoring of rockglacier dynamics.
Under the assumption that permafrost surface changes are detectable by multi-temporal ALS
data, modellers, stakeholders and decision-makers will benefit from the monitoring results
and a sincere data analysis. C4AUSTRIA provides on one hand reliable information about
climate change consequences in the cryosphere and periglacial environment and on the other
hand a comprehensive methodological base for further investigations.
Acknowledgements: The ALS data series was compiled on base the ACRP (Austrian Climate
Research Program) C4AUSTRIA (project number: A963633), the kind contribution of the
Tyrolean Government (surveying department) and the alpS - Centre for Climate Change
Adaptation Technologies project MUSICALS. We are very grateful for the valuable support