Civil Engineering Reference
In-Depth Information
the pure background zone (no depressions, lineaments, etc.), then
c
(
z
1
*
,
t*
)
= c
b
(
z
1
*
,
t*
). If it belongs to an anomalous area of a PFMZ (of a
given assessed type at step 3c), then
c
(
z
1
*
,
t*
)
= c
a
(
z
1
*
,
t*
). If it occupies a
part of background area
F
b
and a part of anomalous area
F
a
, then
c
(
z
1
*
,
t*
) is determined by previously assessed
c
b
(
z
1
*
,
t*
),
c
a
(
z
1
*
,
t*
) and
known corresponding values of infiltration recharge at background
w
b
and anomalous
w
a
areas, according to the flow rate averaging formula:
cztwFcztwF
wF wF
(*,*)
+
+
( *, *)
a
1
a
a
b
1
bb
cz t
(*,*)
=
.
(4.5)
1
aa bb
After the above three stages, the relative contaminant concentration is
assessed at a depth of the groundwater table as an indicator of vulnerability of
the upper groundwater to the described contaminant.
Formula (4.5) is given for the case when the elementary fragment consists of
a part of one-type PFMZ area and a part of a background area. When it consists
of several parts of different-type areas (maybe several types of anomalous zones
with or without the background part), the right-side part will be similar to the
corresponding products in the numerator and denominator. One should note that
equation (4.5) is based on the assumptions of instantaneous mixing of infiltrating
waters from PFMZs and background parts of an assessed fragment of the area.
In reality, during a definite time the contaminant concentration at the groundwater
table depth remains higher under the local PFMZ areas (depressions, lineaments).
However, the mass sum of the contaminant infiltrating into the upper aquifer
in a unit of time within the assessed fragment corresponds to the average
concentration determined by equation (4.5).
Values of the infiltration recharge of the upper groundwater aquifer in the
background and PFMZ areas,
w
b
and
w
a
, are taken according to direct observation
data obtained by lysimetric measurements at experimental test sites or balance
calculations. Contouring of the PFMZ areas is performed using the topographic
maps or aerospace images of higher resolution than those used for zoning of
typical background areas.
In our assessment of groundwater vulnerability and protectability for the
Kyiv region, the background zoning was performed using maps in the scale
1:100,000 and PFMZ zoning by maps in the scale 1:50,000 with refinement by
detailed maps of key experimental sites in the scale 1:10,000.
All the above procedures of final data processing and mapping are performed
either manually (which is very laborious) or with the use of GIS software, for
example, ArcGIS [
McCoy
, 2004].
The obtained area distribution of dimensionless relative concentration
c
1
(
z
1
*
,
t*
) at a depth of the upper groundwater table is a measure of migration
permeability of the unsaturated zone rocks and deposits or cover vulnerability of
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