HR: 1340h
AN: H23B-1315    [Abstracts]
TI: A geostatistical inverse modeling method for simultaneous estimation of hydraulic conductivity and contamination history
AU: * Shlomi, S
EM: shaharsh@umich.edu
AF: University of Michigan, 183 EWRE Bldg. 1351 Beal Ave., Ann Arbor, MI 48109, United States
AU: Michalak, A M
EM: amichala@umich.edu
AF: University of Michigan, 183 EWRE Bldg. 1351 Beal Ave., Ann Arbor, MI 48109, United States
AB: In recent years, various geostatistical inverse modeling methods have been developed for recovering the release history of a contaminant into an aquifer. A major limitation of most of these methods is the requirement to have a fully-known transport model, which usually requires, in turn, knowledge of the aquifer's hydraulic conductivity field. The hydraulic conductivity is never fully characterized in practical applications, however, and its estimation is often the subject of inverse-modeling investigations in hydrogeology. A method based on quasi-linear geostatistical inverse modeling is developed to simultaneously estimate the contamination history of a pollutant into an aquifer and transport parameters such as the aquifer's hydraulic conductivity field. The proposed iterative approach uses point measurements of hydraulic head, contaminant concentration, and, if available, hydraulic conductivity as constraints. The novelty of this method is in the joint estimation of the historic contamination and the transport parameters (e.g. hydraulic conductivity). This approach allows for a more accurate assessment of the uncertainties associated with the final estimates, which reflect the cross-covariance between the two parameters fields, as well as model errors, measurement errors, and aleatory variability inherent to the physical system. Simulations carried out on a two-dimensional hypothetical aquifer demonstrate the applicability of this method under various conditions. Unlike existing geostatistical inverse modeling methods, the present method allows the release history to be retrieved even if transport parameters are not fully characterized. However, these experiments indicate that a relatively large number of measurements is required in heterogeneous applications to constrain the unknown contamination history. In relatively homogeneous aquifers, a smaller number of measurements is sufficient to jointly characterize the conductivity field and contamination history. The approach is applicable to site characterization for remediation design, as well as the identification of responsible parties in cases of groundwater contamination. Additionally, this method can form the basis for approaches aimed at characterizing the current or future distribution of contaminants in aquifers, given uncertainty in the flow and transport parameters, as well as in the contamination history.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1869 Stochastic hydrology
DE: 1873 Uncertainty assessment (3275)
SC: Hydrology [H]
MN: 2007 Fall Meeting