SPCC 4 (SORP): Sensitivity of rock permafrost to regional climate change scenarios and implications for rock wall instability
Project information:
SPCC 4 is part of the ‘Bündel-project: Sensitivity of mountain permafrost to climate change (SPCC)’ and is financed by the German Research Foundation (DFG).
This project aims at understanding the impact of future climate-induced rock permafrost degradation on rock wall instability. Permafrost-related instabilities such as rock creep and rockfalls are assessed at three study sites (Zugspitze, Steintälli, Corvatsch) with geodetic measurements, extensometers, and laserscanning. Distribution of rock permafrost will be assessed at the micro-scale at all sites with combined geophysical measurements. ERT (electrical resistivity tomography) and P-wave refraction seismics reveal 2D and 3D information on ice-content inside rock walls. Processing of these datasets includes laboratory calibration, time-lapse inversion of subsequent measurements, and combined interpretation of seismics and ERT in a 4-phase (rock-air-water-ice) model. Static (lithology, discontinuities, aspect, elevation) and dynamic factors (radiation, rock temperatures, hydrology) are recorded and combined with GPR information (ground penetrating radar) on subsurface rock mass characteristics.
SPCC 4 aims at calibrating and validating the physical rock permafrost model TEBAL (Topography and Energy Balance). Initial conditions for model runs derive from existing geophysical datasets (2005-2007). Site-specific TEBAL-models are calibrated to subsequent geophysical tomographies (2005-2010), while recorded environmental parameters (e.g. rock temperature, radiation) serve as TEBAL input data. Sensitivity of rock permafrost to future RCM (regional climate model) scenarios (radiation, air temperature) developed by SPCC 1 will be modelled with calibrated TEBAL models. The explanatory power of climate-forced rock permafrost degradation scenarios for different site conditions will be evaluated.
Methods:
The research needs for rock permafrost research are to understand spatial and temporal degradation phenomena in response to external factors such as climate as well as the impact of permafrost decay on rock instability. The main objective of this project is (i) assessing temporal and spatial degradation phenomena of rock permafrost under different environmental conditions using combined geophysics, (ii) calibrating physical heat transfer models to the measured permafrost evolution over time and (iii) modelling the impact of regional climate change scenarios on rock permafrost on basis of these calibrated models.
The following research methods will be applied to answer these objectives:
- Combined geophysical measurements: Simultaneous ERT and P-wave refraction seismics will be conducted in 2D and 3D arrays in regular time steps at the three study sites.
- Quantitative permafrost delineation: Calibration of geophysical bedrock data in the laboratory and (at a later stage) 4-phase modelling of combined geophysics.
- Assessment of environmental conditions: Static conditions (surface and subsurface rock mass characteristics) and dynamic conditions (climate) are recorded at all study sites.
- Monitoring of rock instability: Slow and fast rock displacements will be monitored with surface-mounted measurements, geodetic surveys and laserscanning.
- Calibration of physical heat transfer model: The TEBAL model will be calibrated with repeated geophysical datasets and environmental data.
- Rock permafrost degradation scenarios: the sensitivity of the calibrated TEBAL models to anticipated changes in global radiation and temperature as predicted by SPCC1 will be modelled and evaluated.
Study sites:
Preliminary work was conducted as part of the Ph.D.-project ‘Changes in permafrost distribution in alpine rock walls and their implications for mass movements and sediment budgets’ by M. Krautblatter (GRK 437, Supervisor: R. Dikau). Two test sites were equipped and their monitoring is going to be continued and extended in SPCC4.
- The Zugspitze study site is located in the Northern Limestone Alps (German/Austrian border) and ranges from 2770-2950 m a.s.l. and includes west-facing and north-facing parts of the crest line west of the main summit. It consists of Wetterstein limestone, and the summit and the surrounding crestlines are active sources of all magnitudes of rock falls (Mustafa et al. 2003; Krautblatter et al. in press). Gude and Barsch (2005) claim that the Eibsee-Bergsturz, the largest rock fall in the Northern Alps, was connected to permafrost degradation following the Holocene Climatic optimum. The geophysical investigations at this test site started in October 2006 in cooperation with of Dr. A. v. Poschinger from the Bavarian Environment Agency (LfU).
- The ‘Steintälli’ study site ranges from 3070-3150 m a.s.l. and is situated at the crest line between Matter-Valley and Turtmann-Valley in Valais, Switzerland. It consists of paragneiss rocks in all slope aspects and indicates high periglacial/paraglacial activity such as rock creep and rock falls. 2D-ERT and refraction seismic monitoring was measured repeatedly in 2005, 2006 and 2007. A 3D-array with 205 electrodes and 240 geophone positions is installed at the N-S facing crest line was measured repeatedly in 2006.
View at the north-facing part of the ‘Steintälli’ study site. The picture was taken during a helicopter flight.
- The Piz Corvatsch study site, Engadin, Switzerland at 3300 m a.s.l. consists of granite. The monitoring will begin in 2009, including ERT, laser scanning, GPR and refraction seismics.
Contact information:
Prof. Dr. Richard Dikau (supervisor)
Department of Geography, University of Bonn, Germany
Michael Krautblatter (supervisor)
Department of Geography, University of Bonn, Germany
Sarah Verleysdonk (PhD student)
Department of Geography, University of Bonn, Germany
Pauline Oberender (student assistant)
Department of Geography, University of Bonn, Germany
Cooperations:
A. Kemna, A. Florez-Orozco (Applied Geophysics, University of Bonn); D. Morche (University of Halle), M. Moser/J. Rohn (University of Erlangen), A. von Poschinger (Bavarian Environment Agency, LfU Munich), O. Sass (University of Innsbruck, Austria), S. Gruber (University of Zurich, Switzerland), P. Deline (EDYTEM, France), H. Viles (Univerity of Oxford, Great Britain), INFAP, Terrestris, SensorGIS
Links to the other Bündel-projects:
SPCC gemeinsame Homepage des DFG-Bündels "Sensitivity of mountain Permafrost to Climate Change"
SPCC 1 "Ground-atmosphere modelling of permafrost evolution"
SPCC 2 "Quantitative assesment of permafrost degradation using coupled geophysical and thermal monitoring systems"
SPCC 3 "Spatial assessment of permafrost characteristics and dynamics in alpine periglacial environments"
