HR: 0830h
AN: H21E-0900    [PDF]
TI: Block-Effective Macrodispersion for Numerical Modeling of Reactive Solute Transport in Heterogeneous Porous Media
AU: * Lawrence, A E
EM: lawrence@ce.berkeley.edu
AF: University of California at Berkeley, Department of Civil and Environmental Engineering 435 Davis Hall #1710, Berkeley, CA 94720 United States
AU: Rubin, Y
EM: rubin@ce.berkeley.edu
AF: University of California at Berkeley, Department of Civil and Environmental Engineering 435 Davis Hall #1710, Berkeley, CA 94720 United States
AB: The use of numerical simulations for predicting solute movement in groundwater continues to increase in popularity. Simulation accuracy is limited by the fact that, for most sites, few hydraulic conductivity measurements are available leading to a coarse description of the aquifer. Also, even with modern computers, the computational burden of simulating detailed fine grids can lead to the use of large grid blocks. If the hydraulic property variations at scales smaller than those measured and modeled on the numerical grid are neglected, solute spreading will be under-predicted. Rubin et al. (1999) introduced the concept of block-effective macrodispersion to account for the dispersive effects of small-scale variability. The derivation of the tensor ensures that only the otherwise un-modeled variability is accounted for. Block-effective macrodispersion tensors have been shown to accurately account for the effect of un-modeled heterogeneity on the spreading of conservative solutes (Rubin et al., 2003). Modeling of field results has shown that, in many cases, to accurately model solute transport in groundwater, sorption must be accounted for (e.g. Brusseau and Srivastava, 1997). We have derived block-effective macrodispersion coefficients for reactive solutes that experience instantaneous equilibrium sorption with a spatially variable retardation factor and for solutes that experience linear kinetic sorption. We have found that for instantaneous equilibrium sorption, the spatial correlation between the retardation factor and hydraulic conductivity does not affect the transverse block-effective macrodispersion coefficient, while the longitudinal one is affected in the same manner as the total macrodispersion coefficient. Namely, a negative correlation between the retardation factor and hydraulic conductivity increases the longitudinal block-effective macrodispersion coefficient. Both longitudinal and transverse coefficients also depend on the expected value of the retardation factor. Brusseau, M. L. and R. Srivastava, {\it J. Contam. Hydrol.}, 28(1-2), 115-155, 1997. Rubin, Y., A. Bellin, and A. E. Lawrence, {\it Water Resour. Res.}, 2003, in press. Rubin, Y, A. Sun, R. Maxwell, and A. Bellin, {\it J. Fluid Mech.}, 395, 161-180, 1999.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1869 Stochastic processes
SC: Hydrology [H]
MN: 2003 Fall Meeting