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Numerical representation of the geologic framework and its hydrologic and geochemical properties is an integral part of all vadose zone flow and transport modeling. Historically, the geologic framework and the physical distribution of flow and transport properties have been represented by simple homogeneous and horizontally stratified hydrogeologic units. To capture more of the heterogeneity, small-scale variability, and uncertainty within a model, the physical and geochemical parameters may be represented by probability density functions loosely correlated to individual hydrogeologic units. As computer-processing capabilities have become more advanced, there has been more emphasis on improving spatial resolution and quantifying uncertainty in key model parameters. One of the more popular approaches has focused on geostatistical simulation of the flow and transport properties themselves, with little regard to the geologic strata and sedimentary sequences. However, newer approaches are focusing more on geostatistical simulation of the sequence-stratigraphic relations of lithofacies and the geostatistical distributions of flow and transport properties within those facies. These approaches require more rigorous quantitative treatment of geologic data than are normally supported by the mostly qualitative nature of borehole geologic information. Thus at the Hanford Site, efforts are being made to systematize borehole geologic data to be used in a moremore » quantitative way to define the spatial distribution of flow and transport properties in support of vadose flow and transport simulations. New detailed procedures translate qualitative descriptive information into categorical data, and translate inconsistent quantitative and semi-quantitative data into common parametric data sets. A geologic data management system is being developed to manage and integrate these new interpreted categorical data sets with other existing databases to support synergistic analysis and to improve numerical representation of the geologic architecture.« less |
