HR: 1330h
AN: NS23B-04    [Abstracts]
TI: Analyzing Layers of Soil Colluvia for Reconstruction of Soil Erosion and Holocene Landscape Genesis With Ground Penetrating Radar
AU: Werban, U
EM: werban@geophysik.uni-kiel.de
AF: University of Kiel, Institute of Geosciences, Otto-Hahn-Platz 1, Kiel, 24118 Germany
AU: Dreibrodt, S
AF: University of Kiel, Ecology-Centre, Olshausenstrasse 75, Kiel, 24118 Germany
AU: Rabbel, W
AF: University of Kiel, Institute of Geosciences, Otto-Hahn-Platz 1, Kiel, 24118 Germany
AU: Bork, H
AF: University of Kiel, Ecology-Centre, Olshausenstrasse 75, Kiel, 24118 Germany
AU: * al Hagrey, S
AF: University of Kiel, Institute of Geosciences, Otto-Hahn-Platz 1, Kiel, 24118 Germany
AB: Since the GPR method is suitable to differentiate soil layers with different water content based on the dielectric contrast, we apply it to solve landscape genetic and geomorphological questions.
Historical and recent soil erosion events, caused by surface runoff, are documented in sequences of soil colluvia. These depositional areas called geoarchives often contain dateable objects, such as artifacts (potsherd or bricks) and charcoal. Geoarchives, e.g. colluvial fans and trench in-fills, are used as a source of information about past environmental conditions and for determination of land use impacts caused by human activities. Large exposures are common to characterize soil colluvia stratigraphy, and additional drillings are needed to correlate the layers and horizons found in different exposures.
Often, soil colluvia sequences are characterized by a well defined layering and consecutive layers show different grain size. These layers have different saturation-suction relationships (pF-curve) and varied moisture contents. Our research focuses on radar mapping and characterizing these layers of soil colluvia in consideration of different moisture distributions.
We present measurements with 200 MHz and 400 MHz antennas determined in a catchment area in northern Germany.
Common offset measurements were used to map the distribution of accumulated sediments. GPR travel times were depth migrated to correlate them with the exposure survey. The velocity distribution with depth was determined with multi offset measurements and analysis of reflections of a metal rod in a known depth. TDR measurements in different layers within the exposure are used to verify the moisture distribution with depth. We mapped the boundary between soil colluvium and the underlying parent material (weichselian till, glaciofluviatil sand) and differentiated layers within the soil colluvia. Consequently a more detailed balancing of erosion and accumulation rates to quantify historical soil losses is possible. GPR measurements in soils are due to the fast and nearly non-destructive application and the additional detailed spatial information an excellent supplement of landscape genetic investigations.
DE: 1803 Anthropogenic effects
DE: 1815 Erosion and sedimentation
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly