FIELD EXAMPLE OF DATA FUSION IN SITE CHARACTERIZATION

Application of data fusion to characterization of the Fountain and Lyo ns Formations at a field site incorporates geologic knowledge, geophys ical log data, cross-hole seismic tomography, hydraulic test data, and observations of head to reduce uncertainty associated with subsurface interpretation. These formations consist of channel and overbank depo sits that have undergone variable diagenesis, resulting in more hydrof acies than would have been encountered in the original, unaltered depo sits. The disparate types of available data are integrated to yield a coherent hydrofacies classification through use of discriminant analys is and soft data techniques. This data fusion improves definition of t he complex hydrofacies and increases knowledge of their spatial correl ation. Two hundred multiple-indicator, conditional, stochastic simulat ions of the site are generated, 100 with only hard data and 100 with b oth hard and soft data. Forward groundwater flow modeling using estima tes of hydraulic conductivity from field testing yields smaller head r esiduals for realizations which include soft data. Inverse modeling is used to eliminate hydrofacies realizations that do not honor hydrauli c data and to estimate hydrofacies hydraulic conductivity ranges for t he hard and hard/soft data ensembles. Inverse parameter estimation sub stantially decreases head residuals for both ensembles. Standard devia tions of hydraulic conductivities estimated through inverse modeling a re smaller when both hard and soft data are used to generate the simul ations, even though head residuals are similar within the two ensemble s when these estimated hydraulic conductivities are used.