Full text: Remote sensing for resources development and environmental management (Volume 1)

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

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