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The area offers the attraction of a variety of physiographic soil units, which is 
one of the reasons it was chosen initially by ITC. The main landforms found 
(fig. 2 ) in the area are: 
1. Alluvial valleys (A), mainly along the Guadiana river, which flows approxi 
mately through the centre and serves as the main drainage channel for the 
whole survey area. Some tributary valleys have been delineated separately. 
2. Gently undulating to rolling landforms, in which three categories could be 
distinguished: 
a) Areas (R) characterized by an abundance of more or less rounded pebbles, 
with a diameter from 3-18 cm, inbedded in the soil matrix. These areas 
are presumed to be the result of a past braiding river activity. 
b) Areas (K) characterized by a coarse sandy top soil with an arkose substratum 
and 
c) Areas (M) characterized by heavy clay soils with a depth varying between 
0.25 m to several metres usually containing a calcic horizon. The parent 
material dates from the Miocene Period. 
d) Areas (C) of low hills and colluvial valleys, characterized by medium tex 
tured soils. These areas are situated between the areas of higher hills and 
mountains (see below). 
e) Hills and mountains. They are formed by a variety of metamorphic and ig 
neous rocks varying from schists, quartzites to granites and diorites. Some 
of the lower hills and colluvial valleys in between are cultivated (landform 
(C), see above), the rest are used for pasture if at all. 
The most important units from the point of view of agricultural economy of the 
region are the alluvial and the miocene clay areas. The climate of the region is 
typical Mediterranean with dry hot summers and moderate winters with an 
average precipitation between 450 - 500 mm per year. 
2. OUTLINE OF STUDY 
2.1 General 
Imagery was only taken on a few occasions of the test site area by the ERTS -1 
satellite, on the 29th September 1972 and 9th March 1973. The imagery of Sep 
tember 5th and November 16th 1973 could not be used as it did not become 
available in time for the present study. Unfortunately, during the passage of the 
satellite on 29th September 1972 the area had a cloud coverage of about 50%. So 
the imagery taken, although of good quality from the technical point of view, was 
not useful for interpretation purposes. Practically all efforts were concentrated 
on the imagery of the 9th March 1973, which was cloud free. Moreover stereoscopy 
was precluded because the adjacent run was affected by cloud cover.