HR: 16:30h
AN: H44A-03    [Abstracts]
TI: Joint Application of TDR, GPR and Inverse Hydraulic Modeling to Infer Field Scale Hydraulic Properties
AU: * Wollschläger, U
EM: ute.wollschlaeger@iup.uni-heidelberg.de
AF: Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg, D-69120,
AU: Gerhards, H
EM: holger.gerhards@iup.uni-heidelberg.de
AF: Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg, D-69120,
AU: Schneider, S
EM: stefan.schneider@iup.uni-heidelberg.de
AF: Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg, D-69120,
AU: Roth, K
EM: kurt.roth@iup.uni-heidelberg.de
AF: Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg, D-69120,
AB: Estimating field scale hydraulic properties is still a challenge in hydrology. Most classical methods require undisturbed soil samples that have to be excavated during time consuming and labour intensive field work which is often followed by tedious measurements of hydraulic properties in the laboratory. Since these methods can only be applied with a limited number of samples, often only a few point measurements need to be used to characterize field scale hydraulic properties while layer geometry has to be derived from interpolation of these values and additional drilling. The combination of geophysical measurement techniques and hydraulic modeling offers an attractive alternative to bridge the gap between i) few accurate point measurements that are used to infer local hydraulic properties and ii) spatial mapping of the respective layers over large scales. We use a time series of water contents measured in a soil profile with time domain reflectometry to estimate hydraulic properties of the different soil layers with a 1D hydraulic inverse model. Here, hydraulic properties are estimated from \it in situ \normalfont measurements under natural boundary conditions without the need of excavating undisturbed samples and lab measurements. Water fluxes across the soil-atmosphere boundary, which provide the upper boundary condition for the hydraulic modeling, are measured by an automatic weather station. Assuming homogeneous soil layers and neglecting small scale heterogeneity, multi-channel ground-penetrating radar is used to map the spatial geometry of the different soil layers and to extrapolate the hydraulic properties determined for the soil profile to the field scale. Provided that continuous reflections are present, the method is applicable at scales of hundreds of meters to kilometers.
DE: 1835 Hydrogeophysics
DE: 1866 Soil moisture
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting