We have developed a methodology for inverting tracer test data using
zonation information obtained from two-dimensional radar tomograms to
improve the (typically overly smooth) hydraulic conductivity fields
obtained from conventional inversion of tracer test data. The method
simultaneously yields two-dimensional estimates of hydraulic
conductivity as well as petrophysical relationships that relate
hydraulic conductivity to radar velocity; these relationships can be
assumed to be stationary throughout the area of investigation or to vary
as a function of zonation. Using a synthetic three-dimensional hydraulic
conductivity field, we apply the developed inversion methodology and
explore the impact of the strength and stationarity of the petrophysical
relationship as well as the impact of errors that are often associated
with radar data acquisition (such as unknown borehole deviation). We
find that adding radar tomographic data to tracer test data improves
hydrogeological site characterization, even in the presence of minor
radar data errors. The results are contingent on the assumption that a
relationship between radar velocity and hydraulic conductivity exists.
Therefore the applicability of the proposed method may be limited to
field sites where this condition is partially or fully satisfied.