HR: 09:20h
AN: H51K-04 INVITED     [Abstracts]
TI: Flow and transport in highly heterogeneous aquifers: Fickianity, Gaussianity and anomalous transport.
AU: * Fiori, A
EM: aldo@uniroma3.it
AF: Universita' di Roma Tre, via V. Volterra 64, Rome, 00146 Italy
AU: Jankovic, I
EM: ijankovi@eng.buffalo.edu
AF: University at Buffalo, The State University of New York, 231 Jervis Hall, Buffalo, NY 14260 United States
AU: Dagan, G
EM: dagan@eng.tau.ac.il
AF: Tel Aviv University, Tel Aviv, Ramat Aviv, 69978 Israel
AB: Transport of a nonreactive solute takes place in a three-dimensional, highly heterogeneous porous formation. The heterogeneous structure is modeled as a random collection of inclusions of hydraulic conductivity K; the latter is a random variable characterized by a probability density function (pdf) f(K). With t the travel time of a solute particle reaching a control plane located at a certain distance from the source, the aim is to derive the pdf of t, which is in turn related to the solute breakthrough curve. The problem is solved through a simplified theoretical model derived from the self-consistent approach of Dagan et al. (2003), which is based on the distortion of a solute surface moving through a single inclusion in an unbounded domain with uniform flow at infinity. The theoretical model, which depends only on the statistical properties of K and the mean uniform flow U, is tested against accurate numerical simulations based on the analytic elements method. The derived solution permits to test and discuss a series of transport features and assumptions generally employed in transport analysis. The tendency to Fickianity is analyzed through spatial moments of local concentration C, while the Gaussian assumption often employed in transport studies is studied through the analysis of travel time distribution. The developments lead to a clear assessment regarding the circumstances under which Fickianity and Gaussianity can be assumed, as function of the aquifer's degree of heterogeneity. The occurrence of anomalous transport in relation with the medium structure is also discussed.
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: Fall Meeting 2005