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by water intake wells exploiting the underlying aquifers for water supply to Kyiv.
The aquifer is utilized for water supply to cattle farms in the rural area and
satellite settlements of Kyiv.
The water-bearing complex in Cenomanian (Lower Cretaceous) and
Callovian (Middle Jurassic) deposits occurs at depths from 80 to 150 m over the
whole study area excluding the southwestern part of the Kyiv urban agglomera-
tion. The water-bearing rocks are represented by sands of different granularity
sometimes interlaid with sandstone and limestone. The aquifer is commonly
overlain by the low-permeable layer of the Upper Cretaceous marls and chalks
being absent only in the southern part of the studied area. At its base, a low-
permeable layer of Middle Jurassic clays and siltstone is present. The aquifer is
one of the principal sources for potable water supply to Kyiv City. At present the
total pumping rate reaches 200,000 m
3
/day.
The Bajocean (Middle Jurassic) aquifer is also of regional occurrence within
the study area. The water-bearing rocks are represented by sands. The thickness
of sandy deposits rises in the eastern direction, ranging from a few meters to
40-60 m. The aquifer is confined and the head can reach 280 m. It is one of two
main aquifers being exploited for water supply to Kyiv City. As a result of exploi-
tation, a depression cone of 60 km radius was formed in the aquifer with the head
drawdown reaching 120 m in the center.
Depending on hydrogeological and man-induced conditions (e.g., water
intake operation), the Chernobyl-related groundwater contamination by
137
Cs
and
90
Sr was observed at different concentrations in practically all aquifers in the
regions where the surface contamination initially occurred. According to sam-
pling data obtained in 1992-1997 (over 700
137
Cs and 500
90
Sr samples taken from
wells in the Kyiv and CEZ regions except for the immediate vicinity of the
Chernobyl NPP), the concentrations in the groundwater of the main aquifers
used for the water supply reached 100 mBq/dm
3
and more (Table 2.1).
Table 2.1
Concentrations of
137
Cs and
90
Sr in the groundwater of Kyiv regional
aquifers given as the percentage of total samples in the aquifer for given
concentration ranges. Data collected in 1992-1997.
137
Cs
90
Sr
Sampling
Depth
Interval,
m
<10
mBq/
dm
3
10-50
mBq/
dm
3
51-150
mBq/
dm
3
>150
mBq/
dm
3
<10
mBq/
dm
3
10-50
mBq/
dm
3
>50
mBq/
dm
3
Aquifer
(Age)
Quaternary
2-30
41%
44%
11%
4%
53%
42%
5%
Eocene
45-65
43%
45%
9%
3%
74%
21%
5%
Cenomanian-
Callovian
80-150
50%
36%
8%
6%
80%
20%
-
Bajocean
200-280
51%
36%
7%
6%
75%
24%
1%
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