News from Germany 2000
Germany
published in FROZEN GROUND,
the News Bulletin of the International Permafrost Association (IPA),
Number 24, December 2000
The Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Hannover, and the Centre d'études nordiques, Universite Laval, Quebec, have started a joint-project to investigate the development of permafrost in emerged marine sediments east of Umiujaq, Nunavik, near the eastern shore of the Hudson Bay (cp. also report by Canada). Six holes were drilled into a (mineral) palsa and geophysical equipment installed to monitor the temperature field and water pressures at the palsa base for at least one year. Our intent is to develop from our observations a fully consistent numerical model capable to simulate the full cycle of palsa growth and decay. The area under investigation is considered as a modern analog to conditions that prevailed during the last marine regression from the Laptev Sea shelf of Siberia.
During summer 2000 the Giessen PACE group successfully conducted drilling operations on Stockhornplateau (3410 m a.s.l.), Mattertal. The two boreholes reached a depth of 100,7 and 31 m, respectively. Preliminary temperature readings indicate a permafrost thickness of at least 150 m in this area. Investigations by Stephan Gruber demonstrated the influence of permafrost on landslide hazards in a GIS analysis that was carried-out for a 485 km2 basin in the Mattertal. Permafrost distribution proved to be a highly valuable factor in data-driven modelling of potential landslide hazard in the periglacial belt. A digital elevation model, extensive mapping from aerial photographs, satellite imagery and field work formed the basis for this study. A local permafrost model was designed from calculated potential direct solar radiation totals in summer, terrain elevation and a map of vegetation abundance derived from a Landsat TM image. The satellite image was corrected for atmospheric and topographic effects using the ATCOR3 algorithm. An albedo map derived from the same corrected image has been incorporated into the radiation-based model in order to calculate net short-wave radiation. In the test area Grächen-Seetalhorn Thomas Herz has started a program to investigate the microclimatological conditions within a coarse debris cover in the periglacial belt. First results of a one year period of air temperature measurements indicate a temperature reduction from the surface to the base of the block cover especially in the snow free period. Future investigations will concentrate on the influence of a coarse boundary layer on energy exchange processes between near ground atmosphere and the lithosphere.
C. Kneisel (Trier) has investigated alpine permafrost in recently deglaciated glacier forefields in the Swiss Alps and in northern Sweden. Together with Swiss colleagues (C. Hauck, D. Vonder Mühll) a permafrost occurrence below the timberline was confirmed by geoelectrical measurements in the Upper Engadine. Monitoring of the ground temperatures for a detailed characterization of this sporadic permafrost site are maintained by C. Kneisel and T. Riedlinger (Trier).