An approach to determine equivalent solutions to the geoelectrical 2D inversion problem

Hoffmann, R.; Dietrich, Peter

doi:10.1016/j.jappgeo.2004.03.005

Cited by 18 publications

(4 citation statements)

References 8 publications

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“…Alternatively, Monte Carlo approaches can be used to generate suites of alternative models that match the data equally well, as we have done in this study. Hoffman and Dietrich (2004) demonstrate a deterministic approach to creating equivalent alternative models in a study of the 2D inversion of DC geoelectrical data, a problem that is directly analogous to steady-state hydraulic tomography. Clearly, without a rigorous assessment of parameter uncertainty, our confidence in the results of hydraulic tomography experiments must be greatly constrained.…”

Section: Uncertainty Assessmentmentioning

confidence: 99%

“…The alternative fields for both examples were generated from the true drawdowns using a general approach that is analogous, although stochastic rather than deterministic, to that used by Hoffman and Dietrich (2004) in their study of similar issues for electrical resistivity surveys. The idea was to create alternative fields that reproduce the true drawdowns.…”

Section: Appendix: Generation Of Alternative Fieldsmentioning

confidence: 99%

“…Despite its use of enhanced experimental designs and more sophisticated analysis approaches relative to traditional hydraulicbased characterization techniques, hydraulic tomography is still subject to the same physical principles. Specifically, any finite number of measurements allows the unique identification only of a finite number of combinations or averages of the underlying spatially varying parameter values and there is an infinite number of possible parameter fields that could yield the parameter combinations required to reproduce the head observations (Hoffman and Dietrich 2004;Aster et al 2005;Tonkin and Doherty 2005). No amount of sophistication in our data analysis can undo this inherent nonuniqueness imposed by the physical system.…”

Section: Introductionmentioning

confidence: 99%

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Inherent Limitations of Hydraulic Tomography

Bohling¹,

Butler²

2010

Groundwater

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We offer a cautionary note in response to an increasing level of enthusiasm regarding high-resolution aquifer characterization with hydraulic tomography. We use synthetic examples based on two recent field experiments to demonstrate that a high degree of nonuniqueness remains in estimates of hydraulic parameter fields even when those estimates are based on simultaneous analysis of a number of carefully controlled hydraulic tests. We must, therefore, be careful not to oversell the technique to the community of practicing hydrogeologists, promising a degree of accuracy and resolution that, in many settings, will remain unattainable, regardless of the amount of effort invested in the field investigation. No practically feasible amount of hydraulic tomography data will ever remove the need to regularize or bias the inverse problem in some fashion in order to obtain a unique solution. Thus, along with improving the resolution of hydraulic tomography techniques, we must also strive to couple those techniques with procedures for experimental design and uncertainty assessment and with other more cost-effective field methods, such as geophysical surveying and, in unconsolidated formations, direct-push profiling, in order to develop methods for subsurface characterization with the resolution and accuracy needed for practical field applications.

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Section: Uncertainty Assessmentmentioning

confidence: 99%

Section: Appendix: Generation Of Alternative Fieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inherent Limitations of Hydraulic Tomography

Bohling¹,

Butler²

2010

Groundwater

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“…2D electrical resistivity imaging has been effective in hydrogeological investigations notwithstanding the equivalence problem in geoelectrical data associated with some 2-D interpretation software [21][22]. The combined techniques have been used to study the effect of dumpsite leachate on soil and groundwater contamination in parts of southwestern Nigeria and elsewhere [23].…”

Section: Introductionmentioning

confidence: 99%