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

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
National land use and land cover mapping:
The use of low level sample photography
R.Sinange Kimanga & J.Lumasia Agatsiva
National Resources Institute, University of Manitoba, Canada and Kenya Rangeland Ecological Monitoring Unit
ABSTRACT: A national program is under way to map land use and land cover in Kenya in details with an
objective of rationalizing resource development planning and monitoring. For various given reasons a low
level photographic sampling method was chosen for the data acquisition. In this paper the methodology and
results of a survey carried out in Meru District of Kenya in 1985 are discussed and compared with other
districts. The survey used a standardized land use and land cover classification for the photointerpretation
as well as for accuracy and consistency assessments. Mapping techniques of the data are briefly
A land use and land cover map of Kenya which gives
a general regional crop mix and vegetation cover
types has been documented by Kenya Rangeland
Ecological Monitoring Unit (KREMU) in the Ministry
of National Planning and Development. It used a
combination of methods including landsat imagery,
aerial and ground observations and checks, as well
as local reference knowledge (Agatsiva and Mwendwa
1982). As a follow-up, quantitative statistics and
mapping of the land resources were needed for
planning and management purposes. As a result of
considerations of several events and situations
it led to the adoption of aerial sample photography
for detailed land use mapping in Kenya by KREMU.
Whereas the agriculturally high potential areas
are the bread basket for the whole country they
comprise approximately 20% of Kenya's land area but
contain over 80% of the human population. These
areas comprise of the highlands of an elevation of
above 1500m and a narrow coastal strip along the
Indian Ocean. Population density as high as 500
per km ^ occur in some areas of the highlands. Thus
the importance of the latter region to Kenya cannot
be overemphasized. The apportionment of land in
this region, to different uses is therefore of
gre^t importance to the planners. In this respect
the high potential areas were given a priority.
The rest of Kenya's land area (over 75%) is
semi-arid to arid rangelands with erratic rainfall
of below 600mm a year. It is the most important
region in terms of livestock numbers and wildlife
A 1979 national census showed that Kenya had a
population of 15 million (Kenya 1980), with an
annual growth rate of 4%. This population growth
rate has continually put pressure on especially the
highlands and led to rapid changes in land use
patterns. Some parcels of the land held per family
have diminished to as small an area as one
hectare. In such a parcel, a family may grow a
variety of crops such as maize, beans, potatoes,
bananas, and coffee. A few heads of livestock are
occasionally also raised on small paddocks or near
zero grazing system. The extraction of such
detailed information from landsat imagery is diffi
cult because of the image resolution (59m *79m). A
complete ground cover survey will be formidable in
terms of time, personnel, details, and analysis at
the scale at which it will be necessary to work
at. Traditional stratified cluster sampling has
been found to be inefficient in several ways
especially in speed, accuracy, and natural resource
distribution data (Nigeria 1984).
A large number of excess population are moving
into drier rangelands and introducing new land uses
in those regions (Bernard 1985). Changing habits,
tastes, and product prices are also having a con
tribution to the rapid alteration of regional land
use activities especially in what used to be pre
dominantly pastoral areas. In their reviews on
desertification, Sinclair and Fryxell (1985) and
Campbell (1986) have emphasised and given evidence
showing that desertification does not often proceed
and spread from desert frontiers. But rather, the
forces of desertification arise from the sedentary
occupation, cultivation and degradation of the less
humid marginal zones. This displaces and disrupts
longstanding and self-supporting pastoral systems.
Denying the pastoralists dry season resource areas
leads to overgrazing and environmental deteriora
tion of the desert frontiers. The fusion of the
overgrazed frontiers and cultivation settlements
from marginal frontiers accelerates desertifica
tion. The detection and measurement of these
changes are essential for national environmental
Recent droughts in the sahelian belt have
affected parts of Kenya and generated concern about
potential food shortages. This also accelerated
the development of aerial sample photography as a
means of rapidly estimating crop hectarage. It has
also led to complimentary research efforts being
made into developing procedures for using airborne
digital photometers in assessing crop vigor and
thus potential yields (Peden et al 1985). This
information in real time helps the government to
assess and update its national food strategies.
Beginning in the 1983/84 fiscal year the develo
pment planning process was decentralized (Kenya
1983). A District Development Committee (DDC)
became responsible for planning, implementation and
execution of each district's development programmes
except for certain specified national programmes.
Detailed and accurate environmental and resources
information for development planning became a goal
and a priority for each district. Ultimately, this
information will give an overview of national
resources distribution.
The simplicity in extracting the information from
the photos and the forwarding of that information
to users in real time is a big advantage in this
method. So is its capability in cloud-cover under
flying during the critical crop growing season.
Depending on sampling intensity cost-effectiveness