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marls was taken as 0.1, in agreement with literature data for low-permeable rocks
[
Bochever and Oradovskaya
, 1972].
After the initial parameters were defined, the initial-boundary problem (4.1),
(4.2) was solved numerically using the method of finite differences [
Gladkiy et al
.,
1981], and the vertical distributions of relative
137
Cs concentrations in the ground-
water were calculated for different values of downward flow velocity
w
within its
variation range from 10 to 2000 mm/year. After that, the corresponding assessment
plots of relative
137
Cs concentration
c
2
(
z,t*
) for the forecast period
t* =
30 years
(the half-life time for
137
Cs) were drawn.
The obtained assessment relative concentration plots (as referenced to the
initial concentration of 1 at a depth of the Quaternary aquifer groundwater table)
are shown in Figure 5.8 against depth in the local scale with zero corresponding
C/C
1
0
0.2
0.4
0.6
0.05
0.1
0.15
0.25
0.3
0.35
0.45
0.5
0.55
0
w = 10 mm/year
5
10
w = 100 mm/year
15
w = 200mm/year
w = 300 mm/year
20
25
w = 500 mm/year
30
35
w = 800 mm/year
40
w = 1000 mm/year
45
50
55
w = 1500 mm/year
60
65
70
w = 2000 mm/year
75
80
85
90
95
100
Figure 5.8
Plots of the distribution with depth of the
137
Cs relative concentration in
groundwater infiltrating through the low-permeability bed Kyiv marls corresponding to
different values of vertical flow velocity
w
for the forecast period
t
* = 30 years.
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