M. Ritz et al., Improvement to resistivity pseudosection modelling by removal of near-surface inhomogeneity effects: application to a soil system in south Cameroon, GEOPHYS PR, 47(2), 1999, pp. 85-101
Near-surface inhomogeneities (NSIs) can lead to severe problems in the inte
rpretation of apparent resistivity pseudosections because their effects sig
nificantly complicate the image aspect. In order to carry out a more effici
ent and reliable interpretation process, these problematic features should
be removed from field data. We describe a filtering scheme using two-sided
half-Schlumberger array data. The scheme was tested on synthetic data, gene
rated from a simple 2D resistivity model contaminated by NSIs, and is shown
to be suitable for eliminating such contaminations from apparent resistivi
ty data. Furthermore, the original model without NSIs can be recovered sati
sfactorily from the inversion of filtered apparent resistivity data. The al
gorithm is also applied efficiently to a real data set collected at Nsimi,
in southern Cameroon, along a 200-m shallow depth profile crossing a comple
x transitional zone. For this case, the filtering scheme provides accurate
structural and behavioural interpretations of both the geometry of the majo
r soil constituents and the groundwater partitioning.