Test Site Grenzhof: Application of Geophysical Methods to Predict Field-Scale Flow and Transport ProcessesUte Wollschläger, Kurt Roth
Test Site Grenzhof
Predicting the movement of water and solutes in soils at the field scale is essential for many scientific, agricultural and economical purposes. The water content in the uppermost section of the soil controls, for instance, the local climate, plant growth and groundwater recharge. For modelling and prediction of water dynamics at the field scale a detailed description of the soil's structure is needed which - due to the strong heterogeneity of natural soils - is still a challenge in hydrology. Geophysical methods like ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) are promising tools to non-invasively infer the three-dimensional hydraulic structure of soils at scales of up to several kilometers. In addition, they can be applied for monitoring the dynamics of water content and the movement of tracers.
At the Grenzhof Test Site near Heidelberg, SW Germany we apply GPR and ERT in combination with hydraulic modelling and classical soil physical methods in order to measure, monitor and predict the movement of water and solutes in soils at the field scale.
Water content dynamics is investigated from time series of single- and multi-channel ground penetrating radar measurements through the analysis of ground wave and reflected wave (Wollschläger and Roth, 2005) signals.
Time lapse ERT data from a saline tracer experiment is used in combination with TDR measurements and hydraulic modelling in order to infer the soil's solute transport properties.
A field scale effective hydraulic parameterisation for a soil profile at the test site is obtained from a time series of in situ TDR measured water contents and hydraulic inverse modelling (Wollschläger et al., 2009).
Multi-channel ground-penetrating radar measurement
|The atmospheric boundary conditions for forward and inverse
studies, soil temperature data and TDR measurements of volumetric soil
water content and soil electrical conductivity are provided by an automatic weather station.
The Grenzhof Test Site is linked to projects of the virtual institute INVEST focusing on inverse modelling of terrestrial systems.
U., T. Pfaff, and K. Roth (2009): Field-scale apparent hydraulic
parameterisation obtained from TDR time series and inverse modelling.
Hydrol. Earth Syst. Sci., 13, 1953-1966. [pdf
- Wollschläger, U. and K. Roth (2005): Estimation of temporal changes of volumetric soil water content from ground-penetrating radar reflections. Subsur. Sens. Technol. and Appl., 6(2): 207-218.