Geoscience Reference
In-Depth Information
Fig. 10.3 Photographs of a
homogeneous, saturated sand
pack with seven dye tracer
point injections being
transported, under a constant
flow of 53 ml/min, from left
to right; times at a t = 20
b t = 105 c t = 172
d t = 255 min after injection.
Internal dimensions of the
flow cell are 86 cm (length),
45 cm (height), and 10 cm
(width). Reprinted from Levy
and Berkowitz (
2003
)
transport conditions generally are reached far more quickly than in large, field-
scale applications, because natural heterogeneity appears on virtually all scales
Jury and Fluhler (
1992
). As noted by Berkowitz et al. (
2006
), small-scale heter-
ogeneities do not simply average out.
Even ''perfectly homogeneous'' soils and aquifer materials display heteroge-
neity, and preferential paths for water flow and tracer transport are present. For
example, as shown in Fig.
10.3
and contrary to Fickian transport, contaminant
plumes are not symmetrical ellipses nor are the different plumes identical to each
other. Moreover, measurements of contaminant breakthrough curves in such
