435 
Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Land use from aerial photographs: A case study 
in the Nigerian Savannah 
NJ.Field 
Department of Surveying, Ahmadu Bello University, Zaria, Nigeria 
W.G. Collins 
Department of Civil Engineering & Construction, Aston University, Birmingham, UK 
ABSTRACT: Using medium scale photographs it was possible to estimate the land 
use in a test area of the Nigerian Savannah. A method of primary and secondary 
sampling was applied covering about 17% of the area. Significant changes were 
noted between 1950 and 1972 in woodland, farmland, and grass/scrub. 
Correlations were noted between accessibility and changes in land use. 
1. OBJECT OF THE PROJECT 
1.1 The object of this project was to devise a 
method for monitoring land use and land use 
changes over .areas of the Nigerian savannah 
region, using available aerial photography and 
simple interpretation techniques. Information on 
land use and land resources is not readily 
available and although methods using satellite 
data are very efficient they tend to be out of the 
reach of the ordinary user in a developing country 
because of expense and the lack of equipment for 
interpretation. 
1.2 There is a large amount of aerial 
photography of Nigeria which has been flown at 
different times and was designed for use in the 
production of topographical maps. This material 
is archived after use, and still contains a wealth 
of information on vegetation and land use which 
has not been transferred to the topographical 
maps produced from it. As Philipson (1980) says, 
"if the aerial photography is available, the 
expense of acquiring and analysing other forms of 
remote sensing may not be justifiable." 
1.3 The .project makes use of some of this 
material and obtains land use data from it with 
simple photointerpretation equipment such as would 
be available in most small survey organisations. 
Because of the large volume of data and the 
statistical tests which are necessary to test its 
relevance a microcomputer has been used in the 
processing of the information. It has been shown 
by Emmott (1981) in a pioneering study that"The 
Combination of conventional photointerpretation 
techniques with widely available computer 
facilities provides an efficient means for the 
measurement, storage and representation of land use 
data". 
2. CHOICE OF TEST AREA 
2.1 The test area is covered by the national map 
series Nigeria 1:50,000 sheet 145 NW Kajuru, and 
is an approximate rectangle bounded by longitudes 
7°30 E 7°45 E; and latitudes 10°15'n, IOOso'N; 
with an approximate area of 750 sq km. The 
boundaries were slightly modified because of the 
photographic coverage. 
The area is situated in the southern part of 
Kaduna State immediately to the S.E. of the large 
industrial and administrative centre of Kaduna. 
The topography consists of gently undulating 
plains wide valleys (fadama) , the plains being 
interrupted in the S.W. by frequent rocky hills 
(inselbergs) (see figures 1 and 2) . The 
vegetation and climate are typical of the savannah 
with a 5-6 month growing period during the rains 
from April to September (Kowal and Knabe 1972) and 
it falls within the Northern Guinea savannah zone 
(LRDC 1979) recognised by some writers. 
Population density is nowhere very high, although 
several new market villages have developed over 
the last 30 years. Communications are generally 
poor, but there has been a certain amount of road 
improvement recently which has improved 
accessibility. (see figure 3). 
2.2 The test area was chosen for five reasons: 
1. It is fairly representative of the savannah; 
neither too far south to contain large areas of 
forest or derived savannah, nor far enough north 
to contain Sudan or Sahel vegetation. 
2. The terrain and climate give rise to several 
types of farming systems, the influences of which 
on the landscape, could be interesting to 
investigate. 
3. The influence of the large growing city of 
Kaduna on the nearby rural landscape may be worth 
studying. 
4. The area is covered by 1 : 25, 000 scale 
aerial photography. Other areas, perhaps more 
suitable, are not so well provided for. 
5. The Kajuru area is the site of the annual 
departmental survey camp and is therefore 
convenient and accessible for fieldwork. 
3. SOURCE MATERIAL 
3.1 The test area is covered by three generations 
of aerial photography flown at medium scale in 
1950, 1'962, and 1972. Maps are also available at 
1/50,000, 1/100, 000 and ' 1/250,000 scales, 
prepared from the 1962 photography. For this 
project the 1962 photography was not used directly 
because it is of a smaller scale (1/40,000) than 
that of other years and there would have been 
problems caused by the varying scales and the 
possibility of features recognisable on the other 
photography not being visible. 
3.2 1972 photography 
This photography was taken by Renting Africa