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

Both mountain zones (M) (Figure 3) were covered with indigenous forest (brown-red). On the
Aberdares (M1) vast areas of this have been replanted with coniferous forest (bright red).
On the Ngong Hills (M2) the indigenous forest occurs only as small remnants, much of it has
otherwise been used as firewood and has been replaced by grasslands (yellow).
The escarpment zone (E) (Figure 4) consists of poorly drained large scale dry grasslands
(yellow, blue) in the more western part and in the large depressions caused by faulting
related to the edge of the Gregory Rift. The higher slopes with better drained soils and more
rainfall support the small scale production of foodcrops (mottled pattern of yellow, brown,
green and red). The Muguga, Dagoretti and Embakasi Forests are managed by the Forest Depart
The slope zone (S) (Figure 5) consists of the small scale tea zone (S1), small scale coffee
(S2), large scale coffee plantations (S3), large scale tea farms (S4) and the low density
residential area (S5). Red well drained soils are dominant and the rainfall is sufficient to
support intensive cultivation.
The S1 region consists of small scale farms with tea, limited food production, woodlots and
grasslands (red, pink). Altitude and soil acidity are determining factors in this area. Some
farms have been recently established at the edge of the original forest area M1.
The S2 region is located lower on the slopes and consists of even smaller scale farms pro
ducing coffee and foodcrops with woodlots and grasslands (red) in the valley bottoms arid
around the homesteads. This type of farming results in the clearly outstanding mottled pat
tern of red and green.
The large scale coffee area(S3) has a very sharp northern boundary which was legally estab
lished in the colonial times as the boundary between the native reserve and the area in which
settlers could freely buy the best quality land. The large scale coffee farms represent a
major foreign exchange earner for the country.
The water reservoirs needed for the irrigation of the coffee are clearly visible as black
spots. The shallow soils along the river bottoms and the badly drained depressions are un
suitable for coffee and were turned into grasslands (yellow and red). The river bottoms them
selves are bright red related to the high vegetative production .The Karura, Kiambu and Kamithi
Forests are represented by a darker red caused by the semi-deciduous character of the indig
enous species.
The sharp boundaries of the large scale tea area (S4) date back to policies of the colonial
government. The altitude and the soil acidity determine the suitability for coffee or tea,
however they occur together in the southern part of the area (pink and dark red). The yellow
represents the grassland supporting a succesful dairy industry. Hedges are planted around the
fields and foodcrops occur on the steeper parts of the slopes, both appear red on the FCC.
The western part of the slope zone in between the Ngong Hills and the large scale coffee
farms (S5) shows the encroachment of the urban area of Nairobi on the original indigenous
forest (dark red) and badly drained grasslands (yellow, red). Rural settlements are increa
sing on the lower slopes of the Ngong Hills. The pasture lands and forest remnants of the
hills are visible as a mottled pattern of red, green and yellow.
, The zone defined as plains (P) (Figure 6) is sub-divided in four categories: large scale
rangeland (P1), high density residential, industrial, commercial and transport (P2) , large
scale managed grasslands (P3) and large scale sisal (P4).
The Athi-Kapithi Plains (P1) are the lands communally grazed by pastoralists, without sub
division or individual landownership. The general character is determined by the heavy black
badly drained soils, the rainfall diminishes and the area is generally flat.
The most northern part hosts the Nairobi National Park,where no grazing occurs. This area
stands out because it has less green (bare grey soil) and showes more red.(grass cover).
Riverbeds stand out as red lines. At the eastern side of the Mombasa Road memnants of sisal
estates can be recognized as a brownish colour.
P2 is that part of the plain system, located within the Nairobi City boundary, which has
already been taken over by urban development. The airport region can be recognized as a set
of parallel bright blue lines. High density residential, industrial and commercial develop
ments can all be located within the original dry grasslands (yellow).
Within the managed grasslands (yellow) (P3) some marginal coffee (red) and sisal (brown)
is grown. Recent individual settlements have taken place just outside the city boundary (blue)
Cultivation of sisal (brown) occurs on a large-scale P4), alternating with managed grass
lands (yellow).
In this study the FCC photographic prints
of the LANDSAT images, when combined with
fieldwork, other data and literature study,
presented an enourmous amount of information
in a visually efficient manner. The image is
itself a summary of the physical expression
of the continuous interaction of people and
the natural environment revealing both biotic
and abiotic factors in the combination of in
formation from the visible and near-infra red
portions of the spectrum.
With this knowledge it is possible to design
land-use proposals ultimately tailored to the
need of the individual users within the con
text of local and regional development.
The use of LANDSAT data in this study is at a
relatively unsophisticated level, and as such,
can be easily adopted by all disciplines fo
cussed on land-use planning. The definition
of the mountain, escarpment, slope and plain
zones is neither new nor definite. However
the LANDSAT data can be readily interpreted
into these zones with a spatial location re
lated to topography, vegetation and human
settlement in a way not possible from a con-
vential map. To achieve the same with aerial
photographs is difficult if only panchromatic
photographs are available. The date of such
materials is a matter of choice, so that up
dating would require fieldwork.
Individual systems of categorizing land
scape elements can be applied to the 9tudy
and particular taxonomic systems can be
adopted to describe the Nairobi region (Heet-
man 1979, Tjia 1985).
Multidisciplinary inputs include history
(to explain the delineation of coffee and tea
estates), socio-economics (land availability,