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Title: Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints

Abstract

Our paper describes and demonstrates two methods of providing a priori information to the surface-based time-lapse three-dimensional electrical resistivity tomography (ERT) problem for monitoring stage-driven or tide-driven surface water intrusion into aquifers. First, a mesh boundary is implemented that conforms to the known location of the water table through time, thereby enabling the inversion to place a sharp bulk conductivity contrast at that boundary without penalty. Moreover, a nonlinear inequality constraint is used to allow only positive or negative transient changes in EC to occur within the saturated zone, dependent on the relative contrast in fluid electrical conductivity between surface water and groundwater. A 3-D field experiment demonstrates that time-lapse imaging results using traditional smoothness constraints are unable to delineate river water intrusion. The water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time.

Authors:
 [1];  [2];  [1];  [3];  [1];  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Subsurface Insights, LLC, Hanover, NH (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1257791
Report Number(s):
SAND2016-5315J
Journal ID: ISSN 0043-1397; 641377
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Water Resources Research
Additional Journal Information:
Journal Volume: 51; Journal Issue: 8; Journal ID: ISSN 0043-1397
Publisher:
American Geophysical Union (AGU)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Johnson, Tim, Versteeg, Roelof, Thomle, Jon, Hammond, Glenn, Chen, Xingyuan, and Zachara, John. Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints. United States: N. p., 2015. Web. doi:10.1002/2014wr016129.
Johnson, Tim, Versteeg, Roelof, Thomle, Jon, Hammond, Glenn, Chen, Xingyuan, & Zachara, John. Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints. United States. doi:10.1002/2014wr016129.
Johnson, Tim, Versteeg, Roelof, Thomle, Jon, Hammond, Glenn, Chen, Xingyuan, and Zachara, John. 2015. "Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints". United States. doi:10.1002/2014wr016129. https://www.osti.gov/servlets/purl/1257791.
@article{osti_1257791,
title = {Four-dimensional electrical conductivity monitoring of stage-driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints},
author = {Johnson, Tim and Versteeg, Roelof and Thomle, Jon and Hammond, Glenn and Chen, Xingyuan and Zachara, John},
abstractNote = {Our paper describes and demonstrates two methods of providing a priori information to the surface-based time-lapse three-dimensional electrical resistivity tomography (ERT) problem for monitoring stage-driven or tide-driven surface water intrusion into aquifers. First, a mesh boundary is implemented that conforms to the known location of the water table through time, thereby enabling the inversion to place a sharp bulk conductivity contrast at that boundary without penalty. Moreover, a nonlinear inequality constraint is used to allow only positive or negative transient changes in EC to occur within the saturated zone, dependent on the relative contrast in fluid electrical conductivity between surface water and groundwater. A 3-D field experiment demonstrates that time-lapse imaging results using traditional smoothness constraints are unable to delineate river water intrusion. The water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time.},
doi = {10.1002/2014wr016129},
journal = {Water Resources Research},
number = 8,
volume = 51,
place = {United States},
year = 2015,
month = 8
}

Journal Article:
Free Publicly Available Full Text
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Citation Metrics:
Cited by: 2works
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  • This paper describes and demonstrates two methods of providing a-priori information to a surface-based time-lapse three-dimensional electrical resistivity tomography (ERT) problem for monitoring stage-driven river bank storage along the Columbia River in the state of Washington, USA. First, a transient warping mesh boundary is implemented that conforms to the known location of the water table boundary through time, thereby enabling the inversion to place a sharp bulk-conductivity contrast at that boundary without penalty. Second, because river water specific conductance is less than groundwater specific conductance, a non-linear inequality constraint is used to allow only negative transient changes in bulk conductivitymore » to occur within the saturated zone during periods of elevated river stage with respect to baseline conditions. Whereas time-lapse imaging results using traditional smoothness constraints are unable to delineate river bank storage, the water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time. A surface based ERT array of 352 electrodes was used to autonomously produce four images per day of changes in bulk conductivity associated with river water intrusion over an area of approximately 300 m2 from April through October of 2013. Results are validated by comparing changes in bulk conductivity time series with corresponding changes in fluid specific conductance at several inland monitoring wells.« less
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  • Time-lapse resistivity imaging is increasingly used to monitor hydrologic processes. Compared to conventional hydrologic measurements, surface time-lapse resistivity provides (1) superior spatial coverage in two or three dimensions, (2) potentially high-resolution information in time, and (3) information in the absence of wells. However, interpretation of time-lapse electrical tomograms is complicated by the ever increasing size and complexity of long-term, three-dimensional time-series conductivity datasets. Here, we use three-dimensional (3D) surface time-lapse electrical imaging to monitor subsurface electrical conductivity variations associated with stage-driven groundwater/surface-water interaction along a stretch of the Columbia River adjacent to the Hanford 300 Area, Hanford WA, USA. Wemore » reduce the resulting 3D conductivity time series using both correlation and time-frequency analysis to isolate a paleochannel causing enhanced groundwater/river-water interaction. Correlation analysis on the time-lapse imaging results concisely represents enhanced ground water/surface-water interaction within the paleochannel, and provides information concerning groundwater flow velocities. Time-frequency analysis using the Stockwell (S) Transform provides additional information by 1) identifying the stage periodicities driving ground water/river-water interaction due to upstream dam operations, 2) identifying segments in time-frequency space when these interactions are most active. These results provide new insight into the distribution and timing of river water intrusion into the Hanford 300 area, which has a governing influence on the behavior of a uranium plume left over from historical nuclear fuel processing operations.« less
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