HR: 13:40h
AN: H52B-01 INVITED     [PDF]
TI: Strategies for Dealing with Scaling Issues in Data Acquisition, Characterization and Numerical Modeling of Fractured Aquifers.
AU: * La Pointe, P R
EM: plapointe@golder.com
AF: Golder Associates Inc., 18300 NE Union Hill Road, Suite 200, Redmond, WA 98052 United States
AB: Fractures and their flow and transport properties scale significantly, in different ways and at different rates. Thus, the importance of a factor at one scale may differ significantly at another scale. This implies that characterization, data acquisition, and modeling of fractured aquifers should be carried out at the scale of the process of interest; unfortunately, this is rarely possible. Often data for fractured aquifers are acquired at several scales over different orders of magnitude, and none of them are at the scale of the process of interest. These scaling issues often make it challenging to develop a workflow of data acquisition, characterization and modeling to achieve useful flow and transport predictions. This talk will illustrate, through presentation of field case histories, factors that have proven to be important in a variety of scales, rock types and geologic settings, and strategies for developing project workflows that focus on these factors. First, the factors that govern the connectivity of the fracture network, and control the spatial variations in this connectivity, at the scale of the process heterogeneity, are often the most important factors to accurately characterize, while other factors play a far less important role. To identify what these factors may be, it is useful to distinguish between three scales: the process scale, the heterogeneity scale, and the data scale(s). The process scale, the scale at which a change in pressure, flow or transport is expected to take place in the aquifer is important for the ultimate project results and a function of time as well; the heterogeneity scale, the scale below which spatial heterogeneity in material properties do not impact the predicted results is critical for mathematical or numerical characterization and not a function of time; and the data scales, which are the scales over which the data reflect fractured aquifer characteristics and are essential for upscaling fracture or aquifer properties to the heterogeneity scale, and may or may not be a function of time. Secondly, it is highly beneficial to collect analogous or complementary data on fracture geometry and network flow response at multiple scales. Third, it is often best to have a lot of "soft" data rather than a little "hard" data. Fourth, given the high uncertainty of any fractured aquifer characterization at virtually any scale of interest, it is exceedingly useful to have a means of validating the aquifer characterization. Methods for validating a model of a fractured aquifer to assess whether it is adequate for the purpose intended will also be discussed.
UR: http://fracman.golder.com
DE: 1800 HYDROLOGY
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1869 Stochastic processes
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: 2003 Fall Meeting