latitudes. The 6400 km? study area falls within the jurisdiction of the 
Kerio Valley Development Authority, a regional development agency established 
in 1979. 
Kerio Valley is a narrow trough elongated South-North and formed by 
rifting. It is characterised by a sharp western escarpment (Elgeyo Escarpment) 
with a downthrow of 1500 metres in places, a flat valley floor and a more 
gently rising eastern flank. There is, thus, a large difference between the 
plateaus standing at an altitude between 2400 and 2700m and the valley floor 
which lies at 1200m., with a gradual transition along the slopes. 
From West to East, four main physiographic units can be distinguished: 
- the Uasin Gishu Plateau (2400-2700m) with a highland sub-tropical 
climate. This is a region of large farming (cereals) with some 
forest reserves. . 
- the slopes of Elgeyo Escarpment (from 2400 to 1200m) are covered 
by remains of indigeneous forests, woodland and bushland plus 
cultivated plots in small patches. 
- the Kerio Valley proper, a subarid flat area with poor thorn shrub 
utilized mainly for cattle grazing and some agriculture (especially 
on the banks of the Kerio River). 
- the Tugen Hills -where woodlands, remmants of indigeneous forests 
and agriculture (maize)are predominant. 
METHODOLOGY 
The study was basically carried out by landsat image and aerial photo- 
graphic analysis to compile a geomorphic, habitat and current land use map. 
However, geological and soil maps were already available for the test area. 
1 - Geomorphic and slope map - ( Fig. 1) 
This map gives the basic information needed to complete a land 
capability study as soil physical characteristics are closely related 
to relief pattern. Aerial photographs at a scale of 1/50000 were used 
for slope analysis through stereoscopic vision which is necessary for 
this type of exercise. The main geomorphic features were denoted with 
specific symbols (crest, scrap, break in slope) and the land was 
classified into six geomorphic classes, according to slope gradients, 
thus: 
class 1-slopes between 0° and 1° - Flat lands 
class 2-slopes between 1° and 3° - Very gentle topography 
class 3-slopes between 39 and 79 - Gently undulating surfaces 
class 4-slopes between 7° and 120- hilly and undulating relief 
class 5-slopes between 25%nd 12°- hills and sharp slopes 
class 6-slopes over 259 Mountains and major scarps 
This data was compiled onto 1/50000 topographic sheets and then reduced 
to a scale of 1/125000. 
2 - Habitat and current land use mapping (Fig. 2) 
The main vegetal units were interpreted from landsat images en- 
larged at a scale of 1/250000, at both dry and wet seasons. More 
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