Proyecto Inta/GTZ MSS 
LUDEPA 
Establishing a Geo - Information System 
  
  
  
  
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Interpretation 
  
  
  
  
Classification 
Additional 
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Archive Archive 
Rectification 
GIS GIS 
  
  
Topographic work sheets 
1:250000 
  
  
Archive Patti ens Archive 
ectification 
GIS GIS 
x 
Eco- 
logy 
Desertification Maps 
1:250000 
Monitor 
{true colour) 
512 x 512 
+ Digitizer DIN A1 High quality 
Data eque] l1 11. Lc Prinfer colour image 
sition — ]| gp | [E output 
200 MB Hard disc 
Data prepro - 2 MB RAM 
cessing —{QO} graphic board Lu cie 
Tape and 
streamer unit | es 
Plotter DIN A1 
Disc Hardcopy 
M i {Colour, quicklook) 
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Fig. 5 Hardware configuration for a Data 
Processing Unit 
The issue of seasonal changes, taking into account 
precipitation etc. has not yet been considered, but 
interpolation seems to be possible. 
The quality of LANDSAT MSS data for detecting 
desertification processes was checked in a test area 
(,Jacobacci-Maquinchao“) where good ground truth 
is available. The area, between 41?00/ and 41?25' 
S and 68? 20' and 70? 20' W , had been mapped 
for a FAO/INTA project, applying conventional | 
. interpretation of airborne imagery 1:40 000 and field 
work. The results have been carefully documented in | 
the literature (see SPECK et al., 1982), which served 
as a reference. 
A physiographic map from SPECK was digitized 
and laid over the respective LANDSAT MSS scene 
(Fig. 6). The result shows clearly that nearly all 
physiographic features which had been defined in 
the 1:40 000 black and white aerial photography are 
154 
Fig. 4 Data Acquisition in Transects for a GIS Data 
Base , Desertification Control in Patagonia“ 
detectable in the LANDSAT MSS imagery. Moreover, 
some areas are even represented in more detail than 
by the map, like the eolic pattern around the basin 
of the lake. Of course, only colour may give the full, 
correct information. 
For the 29 different physiographic classes defined in 
SPECK et al. (1982) and deliniated in Fig. 6, some 
examples are given, corresponding to the numbers 1 
to 5 in Fig. 6: 
1. Permanent lake in old lake basin, large saline 
tongue originated by eolic (wind) deposition 
Ancient parallel shorelines with saline areas at the 
lower zones 
2. Main channel with seasonal flow, covered by 
moderately dense vegetation 
3. High undissected basaltic plateau with steep 
scarpments 
4. Low undissected basaltic plateau, some bush 
vegetation 
5. High basaltic plateau with many small shallow 
saline depressions 
All classes, except (2), show severe desertification. 
Geometric precision of the class boundaries is 
somewhat problematic and can not be treated 
analytically, as there exist a strong correlation 
between the ,linguistic precision of class definition" 
and the boundaries. Due to many reasons, we detect 
obvious differences between SPECK's vector map and 
LANDSAT MSS, particularly for the channels covered 
by vegetation (class 2). 
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