Stochastic modeling of transport and degradation of reactive solutes in heterogeneous aquifers

Hydraulic conductivity fields (K) and degradation rate constants (a) are commonly used in predicting the fate and transport of reactive contaminants. The natural heterogeneity in aquifer porous materials and its effect on hydrological parameters such as K and a has to be accounted for by using an appropriate stochastic approach. The spatial distribution of K and its correlation with a were examined. Random fields of K having prescribed mean, variance, and correlation lengths were generated using the HYDRO_GEN method. Transport simulations were conducted for an ensemble of two-dimensionally heterogeneous aquifers. Both positive and negative correlations of K and a were considered. The solute??s remaining mass in both the positive and negative correlation scenarios was found to be, on average, within a small range. Concentration profiles for a positive K-a correlation displayed a more uniform behavior of the contaminated plume, compared to a more variable spreading in the negatively correlated cases.