quently 
ploited 
as wind 
sweet . 
y by the 
and falls 
'asonally 
; may be 
t periods 
of flood 
nificance 
(t season 
g are not 
ultivated 
flooded, 
a tudu). 
ection of 
retention 
ocultures 
ows only 
vn 
Farm sizes are usually small (less than one hectare), and typically include a mix of both 
fadama and tudu. (Goddard et al., 1971; Goddard, 1972). The viability of these farms is further 
compromised by the severe fragmentation which is the norm. This is largely attributable to the 
Islamic law of inheritance, and the threat which this represents to the future viability of farm 
operations is exacerbated by the continuing high rates of population growth. 
PRELIMINARY RESULTS 
The project involves mapping the extent and character of wet and dry season land use/cover, 
using recent Landsat imagery. In addition, a comparison of land use/cover before and after 
construction of the irrigation project is being undertaken. In this section of the paper, prelimi- 
nary results of land use/cover mapping for the dry season using December 1984 imagery, are pre- 
sented. Results of change detection studies for the dry season, using 1984 and 1975 data, are also 
reported. 
METHODOLOGY 
The procedures used in this study may be summarized as follows: 
1. Preparation of unsupervised classifications using December, 1984, Landsat data. 
2. Field studies to check unsupervised classifications and develop suitable categories for super- 
vised classification, 
3. Preparation of supervised ce fa tions using 1984 and 1975 Landsat data, 
4. Comparison of 1984 and 1975 using both image enhancement and classification pine 
5. Field checking of results and comparison with other information on the study ren. EN UT 
Prior to fieldwork, unsupervised classifications were produced using the Dipix ARIES II 
image analysis system. The number of classes generated was based on the statistical characteristics 
of the Landsat data and general knowledge of the different land use/cover types that occur in 
the study area. Original images and the result of classifications for each study site were produced 
as 8 x 10 inch colour prints and transparencies. ; 
Field studies involved comparing the images and classifications with ground cover at selected 
points in each study site. in this way, an urderstanding of the capabilities of the Landsat imagery 
for displaying different land covers and land uses in the area was developed. Field interviews with 
farmers were also carried out. 
The third stage was the development of a classification system and the production of super- 
vised classifications for each study site. The development of a classification system ( Table 3) was 
based upon a number of considerations, including the complex ity of the local agricultural system 
and the scale at which final mapsare to be prepared. Since most loca! farmers practice inter-crop 
ping (Norman, 1975), it is not possible to identify individua! crops from Landsat data, except in 
the case of those crops planted as monocultures. This constrain is acceptable since the change 
information needed for the study does not require identification of individual crops.