‚een the
ude that,
1e higher
ee forest
96 . The
s well as
naly and
observed
eduction
d values
?oing the
tation 1s
lysis of
the one
gth. The
dsat TM
level of
spectral
cal state
-Shah et.
). REP 1s
rere first
at second
of REP
data for
method,
Ci/sq.km
flectance
For plot
ossibility
tial data.
ion with
0, 600,
values of
610 and
hebyshev
93). The
el. For
ectra had
it of first
had been
obtained
ites with
km. The
i] curves
Ci/sq.km
of first
e REP is
| (for 25
It will be
potential
Js forests
ta.
alues of
the soils
on of soil
d by the
integral impact of toxicants on the spectral brightness of
vegetation in the years from 1986 to 1995.
The largest and most intense area of contamination was found
around Chernobyl NPP. It is the starting point for three maximal
of the first order, consisting of local minimal and maximal for
radionuclide concentration. Their location is determined by the
relief maxima for radionuclide concentration. Their location is
determined by the relief structure. The maximum value to the
south of Chernobyl NPP coincides with the well-known southern
trace of the accident. Elevated radionuclide concentrations are
associated with the valleys of the largest rivers, with the northern
edges of forests and local elevations in the relief. Lower
concentrations are typical of southern slopes of watersheds and
southern edges of forests, and form large local depressions in the
relief. The highest contamination, which coincides with the
valley of the River Pripyat, reveals a very small fluctuation range
in the concentration of Cs-137, probably due to the absence of
barriers preventing the transport of radionuclides by the wind.
The spatial distribution patterns of radionuclides shown on the
map accord with those established from ground-based
investigation data, which suggests that the map is a true
representation of the actual situation. — The greatest threat is
posed by zones with elevated infiltration in water-bearing
horizons in depressed parts of the relief. These are the places
where secondary radionuclide contamination of soils, water and
deposits on the beds of enclosed waterbodies is concentrated. A
particular danger is associated when such places coincide with
active fracture zones with elevated downward vertical filtration
of underground water. These conditions are generally found
around the perimeter of ring structures.
R
2.8 —
2.4 —
.
2.0 —
1.6 —
4.2 —]
es v T Y T , T Y 1
500 soo 700 800 900
A, nm
Figure 1. Approximation of Landsat TM data:
where R - relative spectral reflectance;
A - wave length;
initial data of spectral reflectance;
— - approximated curve using Chebyshev
polynomials
Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
dR/dA * 0.01
20
ex
1.0 — 1
? |
|
0.0 — |
|
7 |
|
„1.0 — |
4 |
AN
— |<—
-2.0 Ly e Ho uA S me £1
500 eoo 700 800 900
A, nm
Figure 2. Spectral shift (dL) of red edge position (REP)
of first derivative curve:
1. — first derivative curve of spectral reflectance for
soil contamination 5 Ci/sq.km;
2. --- theone for soil contamination 25 Ci/sq.km
2.4. Modelling of toxicants migration in geosystems
The modelling of energy-mass exchange in geosystems, based on
a generalization of methods for the numerical solution of
filtration, heat exchange and mass exchange equations provides a
applicable means for the quantitative evaluation of processes
occurring in the depths and associated with the movement by
convective and molecular diffusion of components of complex
natural solutions in rocks. One of the main tasks which can be
accomplished in this way is an evaluation of water exchange
intensity in natural water-bearing systems and the forecasting of
contamination dispersion in underground waters a view to
preventive measures.
The migration of toxicants in the aeration zone and the upper
hydrodynamic zone of the Earth's crust, it will be recalled, can be
described by equations from mathematical physics which, in
general terms, may be represented by the formulae (2, 3) for
corresponding boundary conditions:
Filtration:
Div (k grad H) * w = b dh/dt; (2)
Mass exchange:
Div(Di grad Ci) - div (C V) = n dc/dt + dN/dt (3)
where t - time; H - water pressure; Ci, Ni - concentration of i-
component in fluid and solid phase; k - coefficient of filtration of
water-bearing rocks; Di - coefficient of substance dispersion; w -
internal source of fluid; b - compressibility capacity of water-
bearing rocks, V - vector of water movement velocity, n - active
porosity.
