. 
641 
y deformations. 
y dislocations, 
which may a$- 
dump, see 
asis of thoro- 
sing date, 
s not a conti- 
due to thè 
p front. 
thè basis of 
ituation of 
veli as, thè 
slocations, 
uccesive se- 
t possible to 
ollowing pecu- 
liar stages of mass movement: 
- a preliminary stege, and 
- a stage of intensive movement. 
The preliminary stage is characterized 
mainly by upward-lifting movements, which 
occur within the already existing deforma 
tion zone. In the second stage, a rapid 
growth of the toe-failure zone, toward the 
forefield, is noticed. This is accompanied 
by toe-failure landslides at the front part 
of the dump body. 
The cyclic character of the toe-failure 
process is also proved by the comparison of 
the volumes of the heaped and uplifted ma 
sses. This data was extracted from the di 
gital terrain models. 
To characterize the toe-failure process, 
the ratios of the increase of the dump vo 
lume ( P ) to a volume of uplifted masses ( P ), 
were calculated for succesive stages (see W 
Table 1 ) . 
Table 1. 
Period 
P z /p 
w 
May 78 
- July 78 
1.176 
July 78 
- April 79 
0.942 
April 79 
- August 79 
1 .646 
August 79 
- June 80 
1 .235 
In the data listed above, which refers to 
a particullar period of time, generally, the 
volume of dumped masses exceeds (from 18^ 
to 65 /0 average 25 /« ) the volume of uplifted 
masses (except stage 3, April 79, where the 
data reflects the consolidation process of 
the dumped material and the fluffing pro 
cess of the uplifted ground). 
The changebility of P / P ratio shows 
that the toe-failure process can be cyclic. 
The interpretation of remote sensing data 
also shows that the range of the toe-failu 
re process depends on the height of the dump 
layer and the engineering-geological condi 
tions existing on the forefield. 
The influence of the engineering-geologi 
cal condition is represented by different 
shapes of toe-failure borders for the com 
parable loads of dumped masses. 
We can also expect that for soil which 
has the highest moisture content, the shear 
strength can be significantly lower. There 
fore, for such regions, we can expect that 
the toe-failure process will be more inten 
sive. The regions with the highest moisture 
content can easily be recognized on infrared 
and multispectral photos (see Figure 7)* 
However, we can state generally, that the 
increase of the toe-failure zone is mainly 
caused by the increase of the dump height. 
Interpretation of remotely sensed data 
has also shown the evidently negative in 
fluence of phoaphogypsum dump on the natu 
ral environment. This refers mainly to the 
open surface water and vegetation cover» 
It was observed, that contaminations flo 
wing down from the dump area can easily pe 
netrate into the surface water. 
The water circulation is facilitated by 
the flooding (for high water level ) or the 
draining ( for lo\i and normal level ) of the 
Odra i'iver. The water run-off is accelerated 
by the existance of the dump body together 
with the upward-lifting zone itfhich creates 
morphological elevation. 
Figure 4. Contaminants propagation on the 
dump forefield give a specific thermal pa 
ttern (thermal infrared aerial image pro 
duced by an AGA-780 Thermovision System). 
Figure 5• Thermal infrared ground image of 
the dump body. ( Black and white photo is 
for comparison). 
The new drainage pattern is easy to reco 
gnize in all kinds of aeriel photos, espe 
cially on the infrared and thermal infrared 
images.On sueh images, the flooding parts 
and places where polluted water flows into 
the river water can be precisely determined. 
The run-off of polluted water very often gi 
ves a clear thermal effect (see Figure 4). 
The largest amount of suspended matter pe 
netrates into river from the recent front 
part od the dump. This occurs because the 
phosphogypsurn, in this part of dump is not 
yet consolidated. The consolidation process 
and other changes of the dump body can be 
traced on thermal images. 
In Figure 5 zones of radiation temperatu-