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Title
Remote sensing for resources development and environmental management
Author
Damen, M. C. J.

452
7 (180/61 of January 24th, 1976) was specifi
cally used to delineate water bodies, urban-
rural settlement and infrastructure. Band 5
is used for the black and white reproduction
in this paper, showing maximum detail. The
land-cover map 1:1M based on visual interpre
tation of LANDSAT imagery had been completed
and was available for further exploration
(Grootenhuis, Weeda and Kalambo 1986 a).
Background material consulted were:
Geological map, Degree sheet no: 51
NE Quarter, 1971, 1:125.000
Geological map, Degree sheet no: 52
NW Quarter, 1963, 1:125.000
Ministry of Natural Resources, Mines and
Geology Department, Kenya
Exploratory Soil map and Agroclimatic Zone
map of Kenya, 1982, 1:1.000.000
Ministry of Agriculture, Kenya
Route map of Kenya, 1976, 1:1.000.000
Survey of Kenya
Nairobi and Environs, 1978, 1:100.000
Survey of Kenya
Topographical
1 :50.000
map,
Limuru,
Sheet
148/1,1976
Topographical
1 :50.000
map,
Kiambu,
Sheet
148/2,1976
Topographical
1 :50.000
map,
Ngong ,
Sheet
148/3,1976
Topographical
1:50.000
map,
Nairobi,
Sheet
148/4,1976
Survey of Kenya
The optical pantograph and distortion free
overhead projector enabled comparison of the
LANDSAT images and background information at
the same 1:100.000 scale. The multi spectral
additive viewer was used to study various
combinations of bands 4, 5, 6 and 7. A print
taken from the view screen showing a balance
between bands 5, 6 and 7 at scale 1:250.000
was used for crop distinction. The photo
showed a discrimination between coffee, tea
and pineapple plantation in different shades
of orange and yellow. This appears to result
from differences in band 5 and band 6 reflec
tance of these crops.
2.2 Method
A tranparency of the Nairobi and Environs map
1:100.00 was superimposed on the enlarged
LANDSAT print. In consequence, the resulting
geographical reference of the pixels simpli
fied the visual interpretation of the images
in relation to the ground truth. A land-cover
map at 1:1M scale was already available as a
result of previous work in the Nairobi area
with LANDSAT images (Grootenhuis, Weeda and
Kalambo 1986 a)„ This map was projected over
the LANDSAT print, using the distortion free
overhead projector, and the respective zones
were transferred to the 1:100.000 scale map.
By means of the geographical reference, the
boundaries could be checked in the field sup
ported by the topographical maps 1:50.000.
The boundaries were redrawn where necessary.
The identified zones showed homogeneous
patterns, which enabled a representative
choice of sampling points. About six field
inspections were made per zone, depending on
the size and complexity. In this way, sixty
sampling points were located within the 60 km
x 60 km study area. The field inspection
points were located at random along accessible
roads, using a specific land-use data sheet.
The variables recorded, included details on
altitude, landform, soil, drainage, vegetation
land-use and visual characteristics. Cross-
sections were sketched in the field to record
the distribution of landscape elements. The
land-cover/land-use classification system of
the United States Geological Survey (Anderson
1976) was applied. Integration of the visual
interpretation of the enlarged LANDSAT image
with the fieldwork and the consulted back
ground data led to the production of a land-
use map at 1:100.000 scale showing land-use
units (Figure 2).
3 RESULTS
The land-cover map enlarged to scale 1:100.000
and superimposed on the photographic print of
the image at the same scale, provided the
delineation of the land-use zones. The boun
daries were checked using the 1:50.000 topo
graphical maps, and only little adjustment of
their location was necessary. Sharp boundaries
were found around large scale plantations due
to property boundaries. A similar situation
is found at the forest edge where the boundary
is secured by the Forest Department. In cases
of transition between two zones, determination
of the boundary is related to specific physi-r
cal factors (as geomorphology and soil).
Differentiation in texture and tone within
one broad phototonal zone suggested sub-divi
sions were necessary. Gathering additional
knowledge about these areas in the field made
it possible to distinguish the land-use units
within the land-use zone.
During the examination of the photo-tones,
it was found that the same colour can repre
sent different land-uses. For example, the
reflection of coffee, pineapple, foodcrops
and river bottoms in the near infra-red
(band 7) is the same and all appear red in
the FCC. Within the land-use zones, different
tones and textures were identified. The ground
truth provided confirmation of the different
land-use units. Sets of land-use units are
responsible for the mottled patterns within
each zone. The cross-sections and the block-
diagrams of the land-use zones (Figure 3-6)
illustrate the sub-division into character
istic land-use units and their relative dis
tribution in percentages.
The land-use units depict clearly the inter
action between man and his environment.
Agricultural practices relating to altitude,
climate, type of soil, slope and landownership
can now be identified.(Table 3).
Table 1. Key to the land-use zones.
Mapping unit Land—use zone
(M) Mountain M1.M2
(E) Escarpment E
(S) Slopes si - S4
(P) Plains P1 - P4