Page 336 - Soil and water contamination, 2nd edition

Patterns in groundwater 323
56 days 101
ground
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z (m) 97 reference line
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source
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125 days 101
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source 100
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194 days 101
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z (m) 97 1 1 1
96
0.1 0.01
0.1 0.01
source 0.1 0.01
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322 days 101
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source 1 1 1
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6642 6642 6642 92
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Distance (m)
Figure 17.13 Development of the TCM plumes (longitudinal, vertical cross-section) after the placement of a block-
-1
shaped source. Concentrations are given in mg l . Adapted from Rivett et al. (2001).
The two above examples show that dispersion mainly occurs longitudinally and that
transverse dispersion is often small. It is for this reason that seasonal variation (as for example
shown in Figure 17.10) fades out in downgradient direction, whereas spatial variation in
chemical inputs at the soil surface can be traced over long distances along the groundwater
flow lines.

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