Research topics

Depending on the complexity of the processes occurring in porous media, we investigate water and material transport in soils at different saturation states and on different scales. Some of our approaches are:

• Small scale (range ≤ 30cm) by in situ imaging methods: visualization of
  • root induced water fluxes in soils by neutron radiography and X-ray tomography,
  • pH changes and oxygen dynamics in root-influenced and root-influenced soil areas by fluorescence imaging ("dissolved oxygen imaging"),
  • Transport of heavy metals in soil by magnetic resonance imaging (MRI).
• Large scale through
  • the quantitative determination of the soil water content (radial footprint: 670m) by means of long-term measurements of cosmic neutron fluxes at the air-ground boundary,
  • the determination of the electromagnetic soil properties with the help of a sensor network consisting of TDR (Time Domain Reflectrometry) and soil moisture probes,
  • the application of tracers to investigate advective transport mechanisms.

In addition, the experimental data are used to calibrate soil hydraulic properties and transport parameters on different scales ("inverse modeling approach"). After calibration, the mechanisms of water flow and mass transport are quantified. The aim is to estimate groundwater renewal rates and soil water fluxes in porous media. In this way, we hope to contribute to a better understanding of the interactions in the atmosphere-soil profile-groundwater system.

Non-invasive investigation of soil-plant interactions

We analyze the complex interaction of roots and soil using complementary 2D and 3D imaging approaches:

• Neutron tomography
  • root system, soil water distribution and root water uptake
• Combining Neutrons and X-rays
  • Linking soil microstructure to rhizosphere hydraulics
• Combining neutron and fluorescence imaging
  • Biogeochemical gradients (pH, oxygen, water content) influenced by plant root

Kosmische Neutronen zur Erfassung des Bodenwassergehalts

Obtaining area average soil moisture for the root zone with Cosmic-ray neutron sensing (CRNS)

• Passive Neutron detectors
• Non-invasive installation
• Horizontal footprint 20ha
• Integration depth 40cm

ResearchUnit Cosmic Sense: Use and develop CRNS within an interdisciplinary team

• Massive Campaigns to map soil moisture distribution and dynamics at high resolution for small catchments
• Develop a Scanning Probe to obtain spatially resolved information on soil moisture distribution within the footprint
• Use CRNS soil moisture to estimate Groundwater Recharge and measure snow water equivalent to estimate the contribtion of snow melt in recharge

Surface water - Groundwater Interactions

 We aim to understand natural and human impacted systems and their temporal dynamics at the surface water - groundwater interface as well as in shallow aquifers:

• Representative groundwater sampling to access water level, temperature and solute concentrations
• Numerical modelling (e.g. Feflow, Modflow, HydroGeroSphere) to reproduce and evaluate natural and human impacted environments