Ruprecht-Karls-Universität Heidelberg

Terrestrial Systems

IUP - TS - Soil Physics

Soil Physics

Kurt Roth

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Expertise The group's historical core expertise is soil hydrology in warm and in cold climates on spatial scales ranging from a few centimeters to a few hundred meters. It includes the closely related fields of the transport of conservative solutes and of soil-atmosphere coupling. A focus of our research is on the role of the soil's multiscale heterogeneity.


Methodology Our approach closely integrates experimental methods, theory-based modeling, and numerical simulation.


Experimental: Current experiments at the lab-scale mainly involve regular and porous Hele-Shaw cells with light-transmission measurements. Previous work on hydraulic multi-step outflow and multi-step evaporation experiments were discontinued after insurmountable difficulties in transferring the results to field situations became apparent.
Active experiments at larger scales, up to a few meters, are performed at the partly controllable ASSESS test site and occasionally at the Grenzhof test site, both near Heidelberg. The ASSESS site is an upscaled version of a lab experiment, a 20 x 4 x 2 m^3 tank filled with partly non-parallel layers of sand and a small array of soil water content and temperature sensors. The Grenzhof site is a largely undisturbed grassland transformed from agricultural use in 2002. It is equipped with a weather station and several profiles for measuring soil water content and temperature.
We contributed to the setup of several soil-weather monitoring stations at permafrost sites on Svalbard and on the Tibetan Plateau. They are now operated by cooperation partners, the Alfred-Wegener Institute (AWI), Potsdam, Germany, and the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), Chinese Academy of Sciences, Lanzhou, China, respectively.
On the instruments side, we contribute to the application of ground-penetrating radar (GPR) to quantitative soil hydrology by developing and demonstrating corresponding multi-channel and high-precision methods.


Modeling & Theory: The group's main contributions so far were on flow and transport in heterogeneous porous media and on exploring non-equilibrium flow processes during infiltration into unsaturated soil. We currently embark on the study of chaotic and complex environmental systems that range from the classical and abstract L63 attractor to vegetation patterns in dry regions and eventually to land-atmosphere coupling through a land surface that is dynamic due to vegetation or form.


Simulation: We routinely deploy a range of numerical PDE-solvers for unsaturated flow of water (SWMS and MuPhi), solute transport (particle trackers and MuPhi), and propagation of electromagnetic fields (MEEP). On occasion, special solvers are implemented, so far for the thermal and hydraulic dynamics of permafrost soils (using COMSOL Multiphysics), for the turbulent wind field above sand dunes (using FEniCS), and for the dynamics of vegetation patterns (using GNU Octave and MATLAB). We have an active cooperation with the Parallel Computing Group at the Interdisciplinary Center for Scientific Computing (IWR) of Heidelberg University, which gives us access to HPC research codes.


Aggregation: We aim to aggregate the above three pillars - experiment, modeling & theory, simulation - into a comprehensive understanding. Current methods start from data assimilation like the ensemble Kalman (EnKF) and particle filters. They are enhanced wherever our concepts and problems demand it.


Notice We share the material on this page and on its dependents in good faith with the scientific community. It may be used freely for non-commercial scientific purposes under the condition that it is properly cited. For comments, suggestions, or requests please email Kurt Roth.


[image]
Thórsmörk, Iceland: A region steadily reshaped by various geomorphological processes.

 

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