The impact of urban groundwater upon surface water - eTheses ...

MONITORING NETWORKS AND METHODS
grain size that is 10% finer by weight is between 0.1 and 3.0 mm. The Hazen approximation
is:
K=C(d10) 2
K = hydraulic conductivity (cms -1 )
d10 = the effective grain size, (10% finer by weight) (cm).
C = coefficient based on sorting see Table 4.2, (cm -1 s -1 )
Table 4.2 Representative values of the Hazen coefficient for different grain sizes and degrees
of sorting (Fetter, 1994).
Sediment character
Range of ‘C’ coefficient
(cm -1 s -1 )
Very fine sand, poorly sorted 40 – 80
Fine sand with appreciable fines 40 – 80
Medium sand, well sorted 80 – 120
Coarse sand, poorly sorted 80 – 120
Coarse sand, well sorted, clean 120 – 150
Additional work has been carried out by Shepherd (1989) in which he developed a
relationship between grain size and conductivity based on field and laboratory data from 18
published studies. The general formula for the relationship is
K = Cd50 j
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