Stochastic analysis of contaminant transport through nonstationary fractured porous media: A dual-permeability approach

A Eulerian moment expansion through the first order of sigma2p(p = f, m) (sigma2p is the velocity variance in the fracture, p = f, or matrix, p = m, domain) is developed for solute transport in a nonstationary, fractured medium. A dual-permeability model is applied to describe the conceptualized fractured medium where solute convection and dispersion in both the fracture and matrix domains are considered. Hydraulic conductivity distrbutions in both fracture and matrix domains are nonstationary. The stochastic governing equations for the mean concentration and concentration covariance are analytically derived. A numerical method (a finite difference method) is applied to obtain the solutions. The developed method is applied to study solute transport in stationary and nonstationary fractured media. The study results indicate that medium nonstationarity significantly influences the solute transport process. The nonstationary transport theory relaxes many assumptions adopted in stationary theories and paves the way for applying the theory to many environmental projects, especially for uncertainty analysis of solute transport.