Seed funding by Heidelberg University

2019 - ongoing


AHK-4D - High-resolution and high-frequency monitoring of the rock glacier Äußeres Hochebenkar (AHK) in Austria


Follow project updates in our GIScience News Blog, on Twitter (#AHK4D) and on LinkedIn (#AHK4D).

Press releases of recent research on cyclical destabilization of Äußeres Hochebenkar rock glacier:

New paper: Check out our latest paper where we use multisensor monitoring and data integration in order to reveal cyclical destabilization of Äußeres Hochebenkar rock glacier. The paper presents outcomes of a great interdisciplinary research collaboration lead by Lea Hartl (Institute for Interdisciplinary Mountain Research (IGF), Austrian Academy of Science (ÖAW)

Watch this animation of two destabilization phases of the Äußeres Hochebenkar rock glacier revealed through 70 years of digital surface models (Cicoira et al. 2022).

Find further impressions of the AHK-4D project in the short video below:


In this project, we investigate topographic change at the alpine rock glacier Äußeres Hochebenkar, Austria. Based on multitemporal and multi-source 3D point clouds at up to two-week acquisition intervals, we are developing methods to quantify the magnitudes and frequencies of individual processes of topographic change over varying timescales.

We focus on the development of methods that:

  • detect and quantify 3D surface change in multiple directions (Williams et al. 2021) and over different timespans (Ulrich et al. 2021)
  • improve the consideration of uncertainties for quantified change (Winiwarter et al. 2021)
  • detect surface change of small magnitudes (< 0.1 m) more confidently (Zahs et al. 2022a)
  • can be applied to point clouds originating from different 3D close-range sensing techniques and acquisition strategies, such as UAV-borne and terrestrial acquisitions (Zahs et al. 2022b)
  • consider supplementary surface and subsurface information for the interpretation of geomorphic change, e.g. subsurface data from electrical resistivity tomography and time-lapse images (Zahs et al. 2019)

Find an overview of our 4D methods and developed algorithms here.


The rock glacier Äußeres Hochebenkar is continuously monitored through terrestrial and UAV-borne laser scanning and photogrammetry. These data are complemented by information obtained from time-lapse-cameras and subsurface data from electrical resistivity tomographys.


Observed changes to rock glacier surfaces reflect the interaction of various geomorphic deformation processes. These include permafrost creep, permafrost slide, zonal thinning or thickening, advection of surface microtopography, 3D straining, general mass changes (heaving or settlement) and horizontal shearing and rotation. The surface changes induced by these processes feature different spatial characteristics, magnitudes and timescales of occurrence, which are not yet fully understood (Moore 2014, Kenner 2018).
Monitoring 3D surface change at high spatial (centimeter point spacing)- and high temporal (sub-monthly)-resolution, allows to characterise the different geomorphic processes by their spatiotemporal dynamics and to reveal their contribution to surface change on rock glaciers. This information can enhance our general understanding of the spatial and temporal variability of rock glacier deformation and the interaction of rock glaciers with connected environmental systems.

Study Site and Data

The active rock glacier Äußeres Hochebenkar (Ötztal valley, Austria) is continually monitored by us through repeated surveys since 2015. Datasets comprise high spatial- and high temporal (e.g. bi-weekly)- resolution and multisource topographic point clouds, acquired by terrestrial and UAV-borne laser scanning, and UAV-borne photogrammetry. These point cloud datasets are complemented by time-lapse cameras and subsurface electrical resistivity tomography measurements for interpretation of underlying processes.

In addition, the simulation and development of improved laser scanning acquisition strategies is an important consideration of the project. Virtual laser scanning can help to efficiently acquire data sets within given limitations (e.g. spatial and temporal resolution, accuracy, spatial completeness) based on available resources. It can further provide complementary simulated point cloud data to develop and test methods for 3D surface change analysis on rock glaciers.


The rock glacier Äußeres Hochebenkar seen from the opposite side of the valley in 2021.

Project Partners

In this project the 3DGeo Research Group conducts research in close collaboration with:

Collaborative research and research-oriented education at the rock glacier is carried out by the 3DGeo Research Group and the Institute of Geography of the University of Innsbruck in the frame of the E-TRAINEE project and the project Towards sustainable development of natural environments based on continuous remote sensing monitoring.

Conference Presentations

We have presented our latest research about 3D topographic change analysis on complex natural surfaces at the ISPRS Congress 2022 in Nice. Watch the video and find the corresponding papers below.

Open Access Datasets

Multi-temporal terrestrial laser scanning datasets at the AHK rock glacier are openly available on PANGAEA:

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