TY  - JOUR
AU  - Robinet, Jeremy
AU  - von Hebel, Christian
AU  - Govers, Gerard
AU  - van der Kruk, Jan
AU  - Minella, Jean P. G.
AU  - Schlesner, Alexandre
AU  - Ameijeiras-Marino, Yolanda
AU  - Vanderborght, Jan
TI  - Spatial variability of soil water content and soil electrical conductivity across scales derived from Electromagnetic Induction and Time Domain Reflectometry
JO  - Geoderma
VL  - 314
SN  - 0016-7061
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2017-08180
SP  - 160 - 174
PY  - 2018
AB  - Quick, reliable and accurate estimates of soil water content (SWC) at intermediate (slope) to larger scale(catchment) are important for understanding hydrological processes and may be provided by electromagneticinduction (EMI). EMI measures the apparent electrical conductivity of the subsurface (ECapp) which represents adepth weighted average value of the bulk soil electrical conductivity (ECb). The relation between ECb and SWChas generally been investigated in soil cores or using local measurements of SWC and ECb. Studies that investigatedthe relation between ECapp measured with EMI and SWC in considerably larger and internally moreheterogeneous support volumes are far scarcer and cover a limited range of environments with a limited range offactors contributing to ECapp. This study developed a new calibration method to obtain quantitative estimates ofSWC using EMI measured ECapp data in a sub-tropical region in Southern Brazil at sites with different soilproperties. SWC and ECb were measured in soil pits with Time Domain Reflectometry (TDR) probes. CollocatedECapp was simultaneously measured with EMI using different coil separations and orientations to measure overincreasing sensing volume. EMI measured ECapp data were first calibrated against calculated ECapp, which werederived from ECb profiles inserted in an exact EMI forward model. A depth averaged SWC (SWCavg) was calculatedand different calibrations that relate ECapp to SWCavg were evaluated. ECapp measurements of the deepersensing coil configurations could predict best the variability of SWCavg using a non-linear relation. Spatiotemporalvariations of pore water electrical conductivity (ECw) were found to be an important cofounding factor.Temporal variations of ECw and the small temporal variability of SWCavg prevented the prediction of temporalvariability of SWCavg using ECapp measurements. Overall, the combination of both calibration steps resulted inthe description of 83% of the spatial variability of SWCavg from ECapp measurements.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000424178400017
DO  - DOI:10.1016/j.geoderma.2017.10.045
UR  - https://juser.fz-juelich.de/record/841080
ER  -