Assessment of sedimentary budgets and permafrost content with capacitive resistivity
Complementary Chinese topic: Sediment and chemical species transport modelling and environmental risk assessment
The main geophysical objective is to establish capacitive resistivity as a tool to map sedimentary budgets and permafrost occurrence in difficult terrain. The method provides the spatial distribution of electrical resistivity, and in addition, the electrical permittivity over a broad frequency range between 1 Hz and 200 kHz, which constitutes the major innovative aspect. The electrical permittivity of frozen water displays a characteristic dispersion in the measured frequency range, which may be used to estimate ice content in permafrost regions. Over unfrozen ground, the information is useful to determine the thickness of sedimentary layers with different characteristics. The method has been shown to be feasible at the field scale (e.g. Grimm and Stillman, 2015; Przyklenk et al., 2016), but has only sparsely been exploited so far. The second innovation is the logistical advantage of using plate electrodes instead of conventional metal sticks, which are difficult to use on hard rock or frozen ground. We will exploit the advantage to map and characterize sedimentary budgets at a local scale on selected transects. The final objective is to link the information obtained from geophysics with other disciplines, e.g. with remote sensing data analyzed by project S4, and to provide input parameters for modeling of sedimentary fluxes. In this way, the project will contribute to the understanding of previous and the prediction of future sediment fluxes and the relationship with climate changes.
Sino-German complementarity of research
Whereas the focus of the German contribution lies on the geophysical and methodological advancements, including data acquisition and interpretation, the Chinese side will include the data into the modeling of sediment fluxes and water transport. The modeling is normally based on remote sensing data that relies on surface information only. Using geophysical data to provide ground truth in selected regions and to extend surface information to greater depth constitutes another innovation.
Prof. Dr. Andreas Hördt, TU Braunschweig Prof. Dr. Roland Mäusbacher, FSU Jena Prof. Dr. Zhang Fan, ITP
Grimm R.E., Stillman, D.E., 2015. Field test of Detection and Characterisation of subsurface Ice using broadband spectral induced Polarisation. Permafrost and Periglacial. Processes 26, 28-38.
Przyklenk, A., Hördt, A. and Radic, T., 2016. Capacitively-Coupled resistivity measurements to determine frequency dependent electrical parameters in periglacial environment – theoretical considerations and first field tests. Geophysical Journal International 206, 1352–1365.
Anslan, S., Azizi Rad, M., Buckel, J., Echeverria Galindo, P., Kai, J., Kang, W., Keys, L., Maurischat, P., Nieberding, F., Reinosch, E., Tang, H., Tran, T. V., Wang, Y.,Schwalb, A.,2020. Reviews and syntheses: How do abiotic and biotic processes respond to climatic variations in the Nam Co catchment (Tibetan Plateau)? Biogeosciences 17, 1261–1279. DOI:10.5194/bg-17-1261-2020.