How Important Is Uncertainty Quantification to Ground Water Modeling Practitioners: Which Tools Do They Use, and Why (or why not) ?

Wednesday, April 22, 2009: 1:20 p.m.
Coronado I (Hilton Tucson El Conquistador Golf & Tennis Resort )
Timothy R. Ginn* , Civil and Environmental Engineering, University of California-Davis, Davis, CA
Timothy D. Scheibe , Environmental Technology Directorate, Pacific Northwest Laboratory, Richland, WA
Laura Foglia , University of California-Davis, Davis, CA
Hanieh Haeri , Civil and Environmental Engineering, University of California-Davis, Davis, CA
Cynthia N. McClain , Geology, University of California-Davis, Davis, CA
The data limitations of hydrogeology rank it between Astrology and Astronomy.  As a result uncertainty affects every aspect of simulation and/or prediction of subsurface fate and transport, from conceptual models to spatial discretization to parameter values and their evaluation. The literature and conference proceedings are replete with approaches, templates, paradigms and such for treatment of uncertainty, but these are mainly restricted to parameter valuation.  Even so, these tools remain poorly used, especially those of the stochastic analytic sort, leading recently to explicit inquiries about why this is the case, in response to which entire journal issues have been dedicated. In 2006/2007 we made a web-based survey of hydrogeology practitioners including both consultants and academics worldwide as the "marketplace" for techniques to deal with uncertainty.  Results imply significant differences in perceived importance of uncertainty, as well as on methods for uncertainty characterization and analysis, frequency and level of usage, and reasons behind the selection or avoidance of available methods. Results shed light on fruitful directions for future research in uncertainty quantification in hydrogeology, and we note some initial work toward one such direction, the bundling of groundwater age data with piezometric head data in model inversion.