sand, medium sand, coarse sand, gravel (Fig. 3.7). The maximum and minimum
hydraulic conductivity of such media can differ by eight orders of magnitude, and
the change of hydraulic conductivity can reflect the lithologic change of monolithologic vadose zone.
(b) Bi-lithologic vadose zone
The bi-lithologic vadose zone consists of two layers of porous media with large
permeability difference. The upper part is a low-permeability clay layer composed
of clay, silty clay, silt and the like, or combinations thereof, while the lower part is a
high-permeability sand layer (Fig. 3.8) composed of silt, fine sand, medium sand,
coarse sand, pebbles, gravel and the like, and combinations thereof. Groundwater is
stored in the aqueous medium at the bottom. The difference in the permeability of
bi-lithologic vadose zone exceed two orders of magnitude.
Fig. 3.7 Structure of
monolithologic vadose zone
Fig. 3.8 Structure of
bi-lithologic vadose zone
3.2 Method of Groundwater Pollution Source Intensity Rating …
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