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Bohling, Geoffrey C. / A ground penetrating radar study of water table elevation in a portion of Wisconsin's central sand plain
[DNR-050] (1988)

I. Introduction: motivation and objectives,   pp. 1-9 PDF (2.5 MB)


Page 4

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is upward (Freeze and Cherry, 1979, p. 194). One would expect that the
groundwater system would be more sensitive to contamination in recharge
areas than in discharge areas. This is indeed true, but not necessarily for
the most obvious reasons. Stoertz (1985, pp. 13-15) discusses the fact that
groundwater recharge and discharge are transient processes and that
recharge may occur in what is predominantly a discharge area (and vice-
versa). Stoertz (1985, pp. 16-17) also pointed out that upward flux of
water across the water table does not necessarily occur in a discharge area,
especially if the water is discharging laterally through a bank or bluff to a
lake or stream. Therefore, a discharge area is not entirely protected from
contamination, since soil water may flow downward to the water table in
such an area. Moreover, Harkin et al. (1986, p. 15), reported that the
movement of aldicarb from the root zone of plants to the water table is
controlled by soil processes which produce concentration distributions that
are erratic both in space and in time, even given uniform application rates
at the surface. It appears that soil processes are more important in deter-
mining whether a chemical used on an agricultural field will reach the
water table than is the location of that field with respect to the groundwa-
ter flow system.
However, contaminants which enter the groundwater system in a
recharge area will have a longer residence time in the flow system and will
affect a much larger portion of the system than those that enter the


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