Bringing 3-D Hydraulic Tomography Into Field Practice: Opportunities, Complications, and New Developments

3D hydraulic tomography (HT) - in which an aquifer is stimulated via pumping successively at a number of locations and 3D head changes are measured -- has been suggested as a method for detailed aquifer characterization. This is largely due to tantalizingly detailed results that have been obtained from numerical experiments and laboratory "bench-scale" experiments. While promising, these studies have often not considered the realities of implementing full, field-scale 3D hydraulic tomography.

In this presentation, we focus on several recent advancements which seek to move 3D hydraulic tomography from the realm of research towards field-scale application for improving aquifer characterization.

We address the following questions that, while imperative for implementing large-scale 3D HT, have not been adequately addressed in the literature:

1.       How do we design adequately flexible, accurate instrumentation, equipment, and data collection devices for collecting meaningful data with little “noise”?

2.       How can field data collection be optimized under constraints of limited available time, manpower, and instrumentation?

3.       How can data realistically be inverted for the common case of unconfined aquifers and pumping tests that do not achieve "steady state", and where storage parameters may be imperfectly known and heterogeneous?

4.       To what extent will "nuisance effects", such as borehole deviation, wellbore skin, and wellbore hydraulics affect the accuracy, resolution, and uncertainty of obtained heterogeneity estimates?

We will share our insights into these questions, which are current roadblocks to widespread implementation of 3D HT techniques, through discussion of recent developments from characterization efforts at the Boise Hydrogeophysical Research Site (BHRS). The talk will include discussion of recent research towards characterizing this site, including i) Lessons learned from a recent field campaign ii) developments in producing an accurate, flexible field measurement system and iii) detailed numerical experiments assessing 3D HT sensitivity and the influence of nuisance effects.