Within the framework of stochastic theory and the spectral perturbatio
n techniques, three-dimensional dispersion in partially saturated soil
s with a finite correlation scale of log-hydraulic conductivity is ana
lyzed. The effects of spatial variability of the moisture distribution
parameter on the asymptotic spreading behavior of a unsaturated solut
e plume are assessed. This is accomplished by comparing two asymptotic
macrodispersivities and two variance of solute concentration, obtaine
d for a constant moisture content and spatially varied moisture, respe
ctively.