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Using Radar Tomography, Hydraulic Tests, and Tracer Experiments To Characterize Fractured-Rock Flow SystemsEPA Grant Number: U915155
Title: Using Radar Tomography, Hydraulic Tests, and Tracer Experiments To Characterize Fractured-Rock Flow Systems
Investigators: Day-Lewis, Frederick D.
Institution: Stanford University
EPA Project Officer: Broadway, Virginia
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997) RFA Text | Recipients Lists
Research Category: Fellowship - Geology , Academic Fellowships , Ecological Indicators/Assessment/Restoration
The objectives of this research project are to: (1) develop a unified approach to the analysis of multiple data types in fractured rock, including hydraulic tests, tracer experiments, and cross-well radar tomography; (2) combine attenuation-difference radar tomography and numerical models of groundwater flow and solute transport to monitor the migration of an electrically conductive tracer; and (3) estimate the hydraulic and transport properties of permeable pathways.
The approach to combining multiple data types for subsurface characterization has four components: (1) geostatistical simulation to generate realizations of fracture-zone distribution consistent with packer tests estimates of hydraulic conductivity, inferred hydraulic connections, and any available soft data; (2) a set of simulation models for flow and solute transport; (3) the use of tomographic inversion to image the movement of an electrically conductive tracer; (4) a stochastic optimization algorithm to link the first three components and calibrate the geostatistical realizations to the various types of data in a manner consistent with the physical processes underlying the experimental data. The ensemble of calibrated realizations provides a model of uncertainty, given the scarcity and resolution of the data. By applying the method to subsets of the available data, the worth of different types of data may be explored. The approach will be applied to data from the U.S. Geological Survey Fractured-Rock Hydrology research site near Mirror Lake, in Grafton County, NH. This work will yield insight into the nature of flow and transport in fractured crystalline rock. The worth of information collected at the field site will be addressed, and relationships between geophysical and hydraulic/transport properties will be explored. Our results may help guide future multicomponent field campaigns at Mirror Lake and elsewhere.