Grantee Research Project Results
2001 Progress Report: A Method for Characterizing the Vadose Zone and Monitoring Solute Transport
EPA Grant Number: R827114Title: A Method for Characterizing the Vadose Zone and Monitoring Solute Transport
Investigators: Yeh, Tian-Chyi J. , Warrick, Arthur W.
Institution: University of Arizona
EPA Project Officer: Aja, Hayley
Project Period: October 1, 1998 through September 30, 2001 (Extended to September 30, 2002)
Project Period Covered by this Report: October 1, 2000 through September 30, 2001
Project Amount: $359,955
RFA: Exploratory Research - Physics (1998) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Air , Safer Chemicals
Objective:
The objective of this research project is to develop new techniques for identifying distributions of heterogeneity and contaminants in the subsurface.Progress Summary:
Several tasks were accomplished during the past year. Of the most importance, we have developed a new inverse methodology for electrical resistivity survey for monitoring water movement in the vadose zone. A sequential, geostatistical inverse approach was developed for electrical resistivity tomography (ERT). Different from most ERT inverse approaches, this new approach allows inclusion of one's knowledge of general geological structures of an area and point resistivity measurements to constrain the estimate of the resistivity field. This approach also permits sequential inclusion of different data sets, mimicking the ERT data collection scheme commonly employed in the field survey. Furthermore, using the conditional variance concept, the inverse model quantifies uncertainty of the estimate caused by spatial variability.Numerical experiments were conducted to demonstrate effects of orientation of bedding on ERT surveys and to show the usefulness and uncertainty associated with the inverse approach for delineating the resistivity distribution using down-hole ERT arrays. A statistical analysis was subsequently undertaken to explore effects of spatial variability of the resistivity-moisture relation on the interpretation of the change in resistivity to the change in water content in the vadose zone. Core samples were collected from a field site to investigate the spatial variability of the resistivity-moisture relation. Afterward, numerical experiments were conducted to illustrate how the spatially varying relations affect the level of uncertainty in the interpretation of change of moisture content based on the estimated change in resistivity. Other possible complications also are explored.
In addition, we have built and conducted sandbox experiments for verifying our previously developed hydraulic tomography technique to characterize aquifer heterogeneity. Results of our experiments demonstrated the robustness of our hydraulic tomography method.
Future Activities:
We are improving our interpretation scheme for the ERT survey. This new scheme will allow the ERT interpretation to include point measurements of moisture content, and the spatial variability of the relation between moisture content and resistivity. This new scheme allows the ERT to detect moisture content directly, instead of the change in moisture content as conventional ERT inverse models. Therefore, the ERT becomes a cost-effective tool for measuring a large amount of moisture content of a large volume of geological formations. Such a large amount of moisture information can assist our inverse model for the vadose zone. Thus, we can correctly forecast migration of water and contaminants in the vadose zone.Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 5 publications | 5 publications in selected types | All 5 journal articles |
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Type | Citation | ||
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Liu SY, Yeh TCJ, Gardiner R. Effectiveness of hydraulic tomography: Sandbox experiments. Water Resources Research 2002;38(4):1034-1034. |
R827114 (2001) |
not available |
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Yeh TCJ, Liu SY. Hydraulic tomography: Development of a new aquifer test method. Water Resources Research 2000;36(8):2095-2105. |
R827114 (2000) R827114 (2001) |
Exit Exit |
Supplemental Keywords:
electrical resisitivity tomography, hydraulic tomography, sequential and geostatistical inversion., Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Physics, Restoration, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Groundwater remediation, Engineering, Chemistry, & Physics, hydraulic properties, sloute transport monitoring, moisture content, solute transport monitoring, remediation, aquatic ecosystems, environmental rehabilitation, pressure distribution, groundwater contamination, electrical resistivity tomography, vadose zone, groundwater pollutionRelevant Websites:
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.