ASSESSING TEMPORAL MOMENT CHARACTERISTICS OF SOLUTE TRANSPORT PHENOMENA IN HETEROGENEOUS AQUIFERS USING RANDOM WALK PARTICLE TRACKING

Abstract

Solute transport phenomenon is one of the crucial issues in predicting and spreading of a
contaminant plume in natural aquifers. In this study, conservative solute transport simulations were
conducted in two-dimensional heterogeneous aquifers to assess the transitional development of temporal
moment characteristics up to the fourth order associated with macrodispersion phenomena. The aquifer
system investigated here relied on the hydrogeologic data in the southwest of the Netherlands and was
modeled as the heterogeneous aquifer with a certain geometric variance. Three types of physical
heterogeneities in subsurface materials were represented as randomly correlated hydraulic conductivity fields,
which were geostatistically generated under the isotropic assumption of the correlation length. Random walk
particle tracking linked with temporal moment approach, which was based on observed breakthrough curves
at several predefined control planes, demonstrated asymptotic variations of the second and fourth moments.
Results also showed that the degree of the physical heterogeneity affected the degree of the increase of each
moment, indicating that this plume behavior reflected the hydraulic conductivity distribution on which the
evolution of plume was considerably dependent.