Integrated hydrogeophysical modelling and data assimilation for geoelectrical leak detection

Tso, C.-H.M. and Johnson, T.C. and Song, X. and Chen, X. and Kuras, O. and Wilkinson, P. and Uhlemann, S. and Chambers, J. and Binley, A. (2020) Integrated hydrogeophysical modelling and data assimilation for geoelectrical leak detection. Journal of Contaminant Hydrology, 234. ISSN 0169-7722

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Abstract

Time-lapse electrical resistivity tomography (ERT) measurements provide indirectobservations of hydrological processes in the Earth's shallow subsurface at high spatial and temporal resolution. ERT has been used in the past decades to detect leaks and monitor the evolution of associated contaminant plumes. Specifically, inverted resistivity images allow visualization of the dynamic changes in the structure of the plume. However, existing methods do not allow the direct estimation of leak parameters (e.g. leak rate, location, etc.) and their uncertainties. We propose an ensemble-based data assimilation framework that evaluates proposed hydrological models against observed time-lapse ERT measurements without directly inverting for the resistivities. Each proposed hydrological model is run through the parallel coupled hydro-geophysical simulation code PFLOTRAN-E4D to obtain simulated ERT measurements. The ensemble of model proposals is then updated using an iterative ensemble smoother. We demonstrate the proposed framework on synthetic and field ERT data from controlled tracer injection experiments. Our results show that the approach allows joint identification of contaminant source location, initial release time, and solute loading from the cross-borehole time-lapse ERT data, alongside with an assessment of uncertainties in these estimates. We demonstrate a reduction in site-wide uncertainty by comparing the prior and posterior plume mass discharges at a selected image plane. This framework is particularly attractive to sites that have previously undergone extensive geological investigation (e.g., nuclear sites). It is well suited to complement ERT imaging and we discuss practical issues in its application to field problems. © 2020 Elsevier B.V.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Contaminant Hydrology
Additional Information:
This is the author’s version of a work that was accepted for publication in Journal of Contaminant Hydrology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Contaminant Hydrology, 234, 2020 DOI: 10.1016/j.jconhyd.2020.103679
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2304
Subjects:
ID Code:
147478
Deposited By:
Deposited On:
21 Sep 2020 11:10
Refereed?:
Yes
Published?:
Published
Last Modified:
25 Oct 2020 07:16