Dikau Richard

Rockglacier Kinematics in a High Mountain Geosystem

Project Number: CH-4402
Project Type: Dissertation
Project Duration: 01/01/2002 - 09/30/2005 project completed
Funding Source: other ,
Project Leader: Prof. Richard Dikau
Department of Geography
University of Bonn
Meckenheimer Allee 166
DE-53115 Bonn
Phone: +49 228 737234
FAX: +49 228 739099

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Research Areas:

environmental sciences
hydrology, limnology, glaciology

Rockglacier creep, Turtmann Valley, high resolution imagery, permafrost

The study presents a regional approach for the quantification of rockglacier creep in a high mountain geosystem (Turtmann valley, Swiss Alps). By a combination of different methods, rockglacier movements were analysed qualitatively and quantitatively on various spatial and temporal scales. The application of digital photogrammetry and terrestrial geodetic survey enabled the quantification of horizontal velocities and vertical changes. The photogrammetric results demonstrate that small-scale aerial photographs are highly useful to measure changes in rockglacier geometry. Also the combination with high resolution imagery (from HRSC-A), which was applied for the first time in rockglacier studies, has been successful. Thus, displacements were investigated in a large area (meso-scale) and over a time span of 26 years (1975 – 2001). Against that, terrestrial geodetic survey enabled the annual quantification of block displacements on two rockglaciers between 2001 and 2004. The first-time application of dendrogeomorphic techniques for the determination of permafrost creep provided preliminary results for two rockglaciers.
The applied techniques and especially the combination of geomorphic mapping and digital photogrammetry allowed the reliable assessment of the state of activity for 45 rockglaciers. Horizontal and vertical surface changes were analysed on 34 rockglaciers and a clear activity was revealed on 18 of them. Most of the permafrost bodies indicated above-average horizontal velocities compared to other rockglaciers in the Alps. In addition, conspicuous spatio-temporal variations in horizontal velocities and vertical changes were observed. Regarding the temporal variations, a distinct increase in horizontal velocity – probably from the beginning of the 1990s – was ascertained for all investigated active rockglaciers.
The described findings were discussed by consideration of probable controls, such as terrain parameters and climatic influences. Although the data on decisive forcing factors and the knowledge on rockglacier dynamics is limited, it is assumed that the observed speed-up is linked to climatic changes and an increase in ground temperatures, respectively. Thus, the investigated kinematics supports the role of rockglaciers as sensitive indicators for changes in the high mountain geosystem.

Leading questions:
  • Are the applied methods and the available data suited to the quantification of rockglacier creep in high mountain environments? Which advantages, limitations, resolutions and accuracies are revealed by the different methods?

  • Do the applied techniques allow the reliable assessment of the state of activity?

  • What are the mean and maximum values of horizontal as well as vertical displacements; also in comparison to other rockglaciers in the Alps?

  • Do the movements reflect spatio-temporal variations? Is it possible to distinguish seasonal and interannual variations from longterm trends?

  • To what extent are the horizontal velocities and vertical changes conditional upon terrain parameters or climatic influences ?

  • Is it possible to assess the sensitivity of rockglaciers and thus evaluate their geomorphic and environmental significance in the high mountain geosystem?

    Roer, Isabelle. 2005. Rockglacier kinematics in a high mountain geosystem. Dissertation, Universität Bonn.
    pdf Dissertation

    Last update: 3/29/18
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