Optimized arrays for 2-D resistivity survey lines with a large number of electrodes

Abstract

11Previous studies show that optimized arrays generated using the 'Compare R' method have significantly 12 better resolution than conventional arrays. This method determines the optimum set of arrays by reduced by more than thirty times by calculating the Sherman-Morrison update for all the possible two-23 electrode combinations, which are then used to calculate the model resolution values for the four-24 2 electrode arrays. The calculation time is reduced by more then ten times by using a subset of the 1 comprehensive data set consisting of only symmetrical arrays. Tests with a synthetic model and field 2 data set show that optimized arrays derived from this subset produce inversion models with differences 3 of less than 10% from those derived using the full comprehensive data set. The optimized data sets 4 produced models that are more accurate than the Wenner-Schlumberger array data sets in all the tests. 5 6

Two‐dimensional joint inversions of cross‐hole resistivity data and resolution analysis of combined arrays

“…The optimisation method presents practical limitations for more than 60 electrodes where the number of possible arrays exceeds a million; therefore, Loke et al . () suggested using a subset of the comprehensive dataset consisting of only symmetrical arrays. This reduces calculation time by more than an order of magnitude.…”

“…Loke et al . () showed the advantage of this method by using the surface DCR data and compared the results with a Wenner–Schlumberger array.…”

Three‐Dimensional Time‐Lapse Geoelectrical Monitoring of Water Infiltration in an Experimental Mine Waste Rock Pile

“…Recent developments of the ERT method over the past decade have increased the spatial and temporal resolution for hydrogeological processes monitoring, with optimization of measurement protocols using several hundreds of electrodes (Loke et al, 2014a, 2014b, 2015a, 2015b; Uhlemann et al, 2018; Wilkinson et al, 2012) and with two‐, three‐, and four‐dimensional inversion software (Günther et al, 2006; Johnson et al, 2017, 2010; Rücker et al, 2017, 2006). Moreover, new approaches have been developed to integrate geophysical monitoring results into hydrogeological modeling to complement traditional hydrogeological monitoring techniques for laboratory experiments or field scale studies (Binley et al, 2002; Chou et al, 2016; Dawood et al, 2011; Kemna et al, 2002; Koestel et al, 2008, 2009; Robinson et al, 2009).…”

Optimized arrays for 2D resistivity surveys with combined surface and buried arrays

“…The resolution of the central region between the lines of electrodes decreases with increasing distance between the lines. Previous studies show that the maximum depth of investigation (using optimized arrays) of a line of electrodes on the ground surface is about one‐quarter to one‐third the line length (Loke et al ). Thus, the maximum possible separation between the two lines of electrodes to obtain reasonable overlap between the areas with significant resolution is probably about one‐half the line length.…”

“…The vector contains the sensitivity values of the model cells for the new test configuration. Equation () provides a computationally efficient method to calculate the change in the model resolution (Loke et al ).…”