  Hydrogeological flow and transport strongly depend on the connectivity of
subsurface properties. Uncertainty concerning the underlying geological
setting, due to a lack of field data and prior knowledge, calls for an
evaluation of alternative geological conceptual models. To reduce the
computational costs associated with inversions (parameter estimation for a
given conceptual model), it is beneficial to rank and discard unlikely
conceptual models prior to inversion. Here, we demonstrate an approach based on
a quantitative comparison of ground-penetrating radar (GPR) sections obtained
from field data with corresponding simulation results arising from various
geological scenarios. The comparison is based on three global distance measures
related to wavelet decomposition, multiple-point histograms, and connectivity
that capture geometrical characteristics of geophysical reflection images.
Using field data from the Tagliamento braided river system, Italy, we
demonstrate that seven out of nine considered geological scenarios can be
discarded as they produce GPR sections that are incompatible with those
observed in the field. The retained scenarios reproduce important features such
as cross-stratified deposits and irregular property interfaces. The most
convenient distance measure of those considered is the one based on
wavelet-decomposition. Direct analysis of the distances is the most intuitive
and fastest way to compare scenarios.
