Summary
Anisotrop
y of the medium pla
ys a dominant role in shaping the flow pattern in the soil profile. This stud
y anal
yses the effect of anisotrop
y on the horizontal spreading of the flow trajectories from a contaminating source point at the soil surface to a high water table. It considers a phreatic aquifer with infinite lateral extension and uniform sedimentar
y-la
yered soil profile, where a state dependent anisotrop
y factor (SDAF) – A(ψ), and
Mualem’s (1984) anisotrop
y model might be applicable. The numericall
y calculated streamlines portra
y the effect of anisotrop
y, and allow discernment among various anisotropic media. Different flow cases are anal
yzed with regard to their dependence on A(ψ), as well as their dependence on the infiltration rate, and on the orientation of the principal axes. Theor
y indicates that the flux direction is dependent on the capillar
y head and thus on the flow rate. Consequentl
y, it is the infiltration rate, which determines the particular path line from the contaminant source point to the ground water table. Accordingl
y, we have defined the “affected domain” as the domain within the unsaturated profile which is vulnerable to contamination from a source point at the soil surface, and the “affected segment” as the segment on the phreatic surface where pollutants ma
y potentiall
y reach the ground water aquifer. Both are determined with respect to anisotrop
y, infiltration rate, and depth. The non-linear horizontal shift of the contaminant trajector
y indicates that a substantial error ma
y result when adopting a constant anisotrop
y factor.
This study suggests that the maximal horizontal shift is the relevant scale when characterizing the anisotropic flow system. This measure should be taken into consideration when designing a related laboratory experiment or a field monitoring system.