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2 Natural and Social 
Conditions in Patagonia 
Patagonia lies in the southern part of South America 
between 36° and 55° latitude south, approx. The area 
is divided by the Andean Range into a western and 
an eastern part which belong to Chile and Argentina, 
respectively. Only the eastern side is affected by 
desertification, i. e. the Argentine Provinces Neuquén, 
Rio Negro, Chubut and Santa Cruz. They cover an 
area of about 800 000 sqkm which is equivalent to the 
surface of Germany plus Poland plus Czechoslowakia. 
Extent and quality of the desertification process 
has been largely studied and analyzed by different 
official Institutions and governmental agencies but 
this information is scattered and not readily available. 
The official statistics give 70 96 desertification for 
Argentina as a whole including Patagonia. This means 
that in principle all Provinces are affected. One may 
get an idea of its political impact taking into account 
that agriculture and lifestock were the base for the 
nation's economic and social balance. 
There are multiple reasons for desertification in 
Patagonia. They are the result of natural conditions 
and human activities. Conditions for agriculture 
activities including animal production have never 
been favourable due to topography and the prevailing 
climate which do not offer suitable ‘alternatives for 
investment. The „environmental balance“ is very 
sensitive to minor changes of the parameters. 
From these parameters we have selected two in order 
to show how the degradation process works: 
a) As a natural factor we take the precipitation rate. 
It is evident that the Andean Range acts as a barrier: 
rainfall values drastically go down from 2 000 mm to 
200 mm from west to east. The most striking factor 
is that this gradient occurs within a distance of only 
100 km or even less. As a consequence, only a very 
small strip at the Andes receives sufficient rainfall. 
»Sufficient^ means a rate in the order of 500 to 1 000 
mm, depending on latitude, topography and soil type. 
The Andes are the domir:ating feature governing the 
natural conditions in Patugonia; even temperatures 
do not only follow a north-south gradient, but a 
strong east-west gradient as well. Compared to the 
northern hemisphere, the mean annual temperature 
of 10° C at 42° C latitude (corresponding to Roma, 
15° C) is extremely low. 
b) As to land use, sheep farming is the most important 
factor. Sheep are almost exclusively reared for wool 
production. In the period from 1888 to 1908 the 
animal population grew from 290 000 to 4.3 million, 
reaching 12 million in 1983. This resulted in heavy 
overgrazing which is one of the most significant 
factors for desertification caused by anthropogeneous 
activities in this very sensitive environment. 
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Since rainfall and other natural processes may not 
easily be influenced by man, desertification control 
should start with those factors dominated by him like 
sheep farming, for example. However, one has to take 
into account social and political constraints which 
actually turn out to be stronger than all arguments 
forwarded by science. 
3 Environmental Monitoring 
Using GIS-Technology 
Monitoring the environment will provide details 
about the interaction of the various parameters 
involved in the desertification process. The analysis 
finally will lead to a quantitative model, which may 
be applied to an area where the necessary data are 
available. This will result in information about the 
status of the environment, which should be one of 
the basic elements to decide about feasible control 
measures. 
The process is depicted in the diagram of Fig. 2. 
Experimental Stage 
      
Additional 
Information 
Data Base G 
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(test areas devil 
Men} 
Model of 
Real environment for 
environment desertification 
  
9 
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COSS Hif; 
OR cation 
Data Base GiS Ro 
(Patagonia appe? 
complete) 
Operational Stage 
Fig. 2 Scheme for Environmental Monitoring Using 
GIS Technology 
In a first step, a „Model“ must be set up 
taking into account the most significant parameters 
involved. This model should be drawn from the 
real environment, or, more specifically, from data 
acquired, for example, by Remote Sensing Techniques 
or in some other way. 
The most important step is the development of 
a GIS. It consists of a model of the environment 
for desertification analysis. This essential task may 
only be accomplished by interdisciplinary work, by 
the joint effort of ecology, soil science, biology, 
sociology, hydrology and data processing experts. 
The establishment of a GIS requires data from well- 
known test areas used like „training fields“ as for 
multispectral classification. 
The GIS will be the basis for providing the following 
features: 
1. Type and degree of desertification 
2. Endangered areas, probability of desertification