News from Germany 1999

Germany
published in FROZEN GROUND,
the News Bulletin of the International Permafrost Association (IPA),
Number 23, December 99

Permafrost aggradation and degradation during the last 200 000 years was simulated numerically for two sections across Northern Germany by BGR (Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover) as part of the multinational EU-project PAGEPA. The calculation is based on a detailed climate curve for this time period (provided by Boulton, University of Edinburgh) and the detailed knowledge of the geological subsurface conditions. Our calculations suggest up to 8 periods of permafrost development in this time period with maximum permafrost thickness varying between less than 40 m to about 150 m. The role of rivers and lakes in preventing permafrost development (talik-formation) was included in this modelling effort. Special attention was paid to likely permafrost degradation scenarios in front of the Scandinavian ice shield at the time of its maximum advance into Northern Germany during the Weichselian stage.

The Research Unit Potsdam of the Alfred Wegener Institute for Polar and Marine Research (H. W. Hubberten) coordinates the multidisciplinary terrestrial portion of the joint German-Russian project "Laptev Sea System 2000". As a part of this research project, we undertook the initial expedition to the Lena Delta region in July and August of 1998. The expedition group was divided into three teams, each with a particular scientific focus: Team 1 which focused on modern processes in permafrost- affected soils and used a biological station of the Lena Delta Reserve on the Samoylov Island in the central part of the Lena Delta. Instruments were installed at 4 measuring sites during 1998 fieldwork. Ongoing multidisciplinary studies focus on the seasonal variability of modern processes in tundra soils. The main scientific objectives were: 1. energy and water balances of the active layer and the uppermost permafrost horizon; 2. quantification of climatic, pedogenic and soil microbial parameters which control the production, oxidation and emission rates of trace gases in soils; 3. carbon flux balances (CO2, CH4) at differing tundra sites within the study area. Team 2 focussed on modern and ancient sedimentation in the Lena Delta and worked aboard the vessel Dunay. The main scientific goals were: 1. sedimentation history reconstruction of the Lena Delta; 2. an understanding of the influence of global, regional and local climatic variability on sedimentation in the Lena Delta; 3. the modern and ancient sediment budget of the Lena Delta.

Team 3 focused on climate signals in ice-rich permafrost deposits and worked at the key section of the Late Pleistocene Ice Complex, "Mamontovy Khayata", on the Bykovsky Peninsula. Their multidisciplinary research program includes: 1. complex cryolithological studies; 2. ground ice research, especially on ice wedges of differing ages using various isotope and hydrochemical analyses; 3. systematic paleontological research (mammal bones, insect fossils, rodents, plant remains, seeds); 4. extensive sampling for radiocarbon and OSL dating; 5. a study of modern geocryological processes. The second expedition, started in April 1999, consists of 7 field group stages. They seek to study the processes listed above for a full seasonal cycle, from the spring to the late autumn. Sediment coring from the ice cover on lakes and lagoons in the spring, and an extensive coastal process investigation in the Lena Delta and Laptev Sea in summer comprise an investigation of the environmental history of the Lena Delta. Paleoclimatic signals in ice-rich permafrost are investigated on the Bol’shoy Lyakhovsky Island and extend the sample base created in 1998. In addition, projects with the following emphases are currently underway: hydrologic and thermal dynamics of the active layer, silicate weathering and the carbon cycle in high Arctic soils. Automated sites were installed in 1998 close to Ny-Ålesund, Spitsbergen and on Zackenberg, East Greenland. Water, gas and soil sample and data collection occur at least annually.

To understand the sedimentation and environmental history of the Lena delta different geological and geophysical approaches were chosen. To identify sedimentary and permafrost structures within the Lena delta sampling of sedimentary sequences by shallow coring and through natural exposures, ground penetrating radar and shallow seismic studies have been carried out. Age determinations are based on radiocarbon and OSL dating. Mineralogy and geochemistry of the sediments show details about the processes controlling the late Quaternary conditions of accumulation and deposition. The geophysical methods of sub-bottom profiling were two-fold: (1) A RAMAC impulse radar system proved to be a viable technique for mapping subsurface structures on land. The 100 MHz radar signal penetrated the permafrost down to 30 m at maximum showing periglacial features like ice wedges and ice layers. Drilling results were used to determine the geologic composition. (2) A sediment echo sounder was used as high-frequency pulse source for seismic surveying of sediments of Lake Nikolay in the western Lena Delta. It was possible to characterize the geometry of basin fills and changes in lake sedimentation as well as to identify the permafrost table below talik zones.

H. L. Jessberger (Bochum) with his team of geotechnical engineers continued in application of artificial ground freezing mainly for tunneling in Germany and abroad. This technology is used e.g. for the subway line U5 in Berlin downtown. The subsoil is dominated by Holocene sand with high water table. Freeze pipes, placed in microtunnels, produce a frozen soil ring of at least 2 m thickness. For high capacity railroad tunnels and road tunnels of 3.5 to 6.5 km length in the Netherlands artificial ground freezing has to be used for the construction of traverse galleries between the two parallel main tunnel tubes. The traverse galleries of up to 26 per tunnel are constructed in very difficult subsoil conditions like fine to medium sand or very soft organic clays and with high water content and with about 400 kN water pressure. The relevant tunnels are crossing partly the Rotterdam Harbor (Botlek railroad tunnel), the Westerschelde (Westerschelde Tunnel at Vlissingen) and Groene Hardt Tunnel. In Boston (USA), Rome and Naples (Italy) are several major ground freezing applications in design state. The International Symposium on Ground Freezing (ISGF) and Frost Action in Soils was held in Luleå (Sweden) 1997 with the main topics (s. Proc. Intern. Symp. Ground Freezing and Frost Action in Soils, Balkema Rotterdam, 1997): heat and mass transfer in freezing and thawing soils and rock, frost susceptibility and frost heave, mechanical properties of frozen, thawed and thawing soils and rock, environmental soil freezing, engineering design, case histories. The next Symposium will be held in Brussels in September 2000. For contact: J.-F. Thimus, UCL, Génie Civil-Batiment Vinci, Place du Levant I, 1348 Louvain la Neuve, T.: +10-47-21-12, F.: +10-47-21-79.

The Geographical Institute of the University of Giessen continued its studies in the EU-Project PACE. In summer 1999 extensive field checks were carried out concerning periglacial and natural hazard features in the whole valley. They will contribute to an evaluation of remote sensing techniques for valuation and eventually prediction of natural hazard features on the one hand and to the development of a glaciological map on the other. At the new test site Grächen-Seetalhorn geomorphological mapping of periglacial features and microclimatological measurements in the surface layer of a coarse blocky debris flow will be carried out. In the thesis of M. Schlerf possible correlations between slope processes and the permafrost distribution were analysed by the use of a Geographical Information System (GIS). Slope processes were surveyed by geomorphologic mapping, permafrost distribution was investigated by modelling (PERMAKART (F. Keller) and PERMAMAP (M. Hoelzle)) and BTS-mapping. The results of the geomorphologic mapping show many different periglacial forms and processes in the Gornergrat area such as rockglaciers, solifluction, rockfall and debris flows. By combining the results of the permafrost models and those of the BTS-measurements calculation of a realistic permafrost distribution was carried out. The results of the GIS-analysis indicate a dependency of solifluction forms by permafrost. The activity of rockglaciers seems to be closely connected to the occurrence of perennially frozen ground. Modelling of rockfall- and debris flows-trigger zones show that both processes can occur in permafrost- as well as in non-permafrost areas.

Alpine permafrost is studied in the Zugspitze summit area (highest peak in Germany) as part of the EU-project PACE by M. Gude (Department of Geography, Jena) in co-operation with Dietrich Barsch (Heidelberg) and Lorenz King (Giessen). Permafrost thermal conditions are monitored by permanent measurements of temperatures in several sites on surface and within bedrock. Based on the models PERMAKART (F. Keller) and PERMAMOD (M. Hoelzle) the distribution of permafrost in the area is evaluated. Monitoring and model results is aimed to improve risk assessment and management related to melting permafrost and slope instability in the area. The occurrence and ecological implications of sporadic permafrost in block scree slopes of non-alpine mountains in central Europe (altitudes less than 1000 m a.s.l.) is subject of a joint research programme by Martin Gude/Roland Mäusbacher (Department of Geography, Jena) in co-operation with Roland Molenda (Department of Zoology, Jena) and other biologists from different departments. Main subject of the project is to understand the thermal regime and the stability of these extraordinary permafrost sites by means of field monitoring and modelling approaches. Ground temperatures are already monitored in several block scree slopes in Germany and France since four years. Investigations on snow hydrologic processes and related sediment transports in the permafrost area of Swedish Lappland (Kärkevagge, Abisko area) are continued by Martin Gude in co-operation with Dieter Scherer (Department of Geography, Basel, Switzerland) and Christer Jonasson (Abisko Scientific Research Station) in the framework of MOSAIC (Modelling of Snowmelt and its Consequences). A field measurement campaign was undertaken in 1998 and next field research is planned for 2000.

A. Beylich, Halle started studies in the field of gravitational and fluvial mass transfers in Austdalur (Austfirðir, East Iceland). In a study on the drainage basin Austdalur (23 km²), located in the mountains of the Icelandic Eastern Fjords (Austfirðir), recent gravitational and fluvial mass transfers in a subarctic-oceanic periglacial environment free of permafrost with Pleistocene glaciations and a steep, alpine relief are analysed. By a combined recording of slope denudation and streamwork information on the absolute and relative importance of the different geomorphological processes for slope and valley formation, on the temporal and spatial variability of the processes, on process intensities or frequencies, on the geomorphological sediment budget of the drainage basin, and on recent trends of relief development is collected. Regarding the annual mass transfer [t*m/yr] the fluvial sediment transport in the main channels clearly dominates over slope processes. The fluvial transport of solids is more important than the fluvial transport of dissolved salts. Aquatic slope denudation (slope and rill wash) is the most important slope process, followed by geochemical denudation, ground avalanches, rockfalls/boulder falls, creep, debris slides/debris flows, and deflation. The intensity of the recent processes is low.