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Title: Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography

Abstract

The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper we use time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river during high stage conditions. We demonstrate a modified time-lapse inversion approach, whereby the transient water table elevation is explicitly modeled by removing regularization constraints across the water table boundary. This implementation was critical for producing meaningful imaging results. We inverted approximately 1200 data sets (400 per line over 3 lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location ofmore » river water intrusion beneath each line. The results reveal non-uniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity ‘break through’ curves and longer river water residence times. The time-lapse ERT inversion approach removes the deleterious effects of changing water table elevation and enables remote and spatial continuous groundwater-river water exchange monitoring using surface based ERT arrays under conditions where groundwater and river water conductivity are in contrast.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1086408
Report Number(s):
PNNL-SA-88529
KP1702030
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Water Resources Research, 49(3):1693-1708
Additional Journal Information:
Journal Name: Water Resources Research, 49(3):1693-1708
Country of Publication:
United States
Language:
English
Subject:
electrical resisitivity tomography; inversion; imaging; geophysics; groundwater; 300 Area

Citation Formats

Wallin, Erin L., Johnson, Timothy C., Greenwood, William J., and Zachara, John M. Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography. United States: N. p., 2013. Web. doi:10.1002/wrcr.20119.
Wallin, Erin L., Johnson, Timothy C., Greenwood, William J., & Zachara, John M. Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography. United States. doi:10.1002/wrcr.20119.
Wallin, Erin L., Johnson, Timothy C., Greenwood, William J., and Zachara, John M. Fri . "Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography". United States. doi:10.1002/wrcr.20119.
@article{osti_1086408,
title = {Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography},
author = {Wallin, Erin L. and Johnson, Timothy C. and Greenwood, William J. and Zachara, John M.},
abstractNote = {The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper we use time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river during high stage conditions. We demonstrate a modified time-lapse inversion approach, whereby the transient water table elevation is explicitly modeled by removing regularization constraints across the water table boundary. This implementation was critical for producing meaningful imaging results. We inverted approximately 1200 data sets (400 per line over 3 lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal non-uniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity ‘break through’ curves and longer river water residence times. The time-lapse ERT inversion approach removes the deleterious effects of changing water table elevation and enables remote and spatial continuous groundwater-river water exchange monitoring using surface based ERT arrays under conditions where groundwater and river water conductivity are in contrast.},
doi = {10.1002/wrcr.20119},
journal = {Water Resources Research, 49(3):1693-1708},
number = ,
volume = ,
place = {United States},
year = {2013},
month = {3}
}