Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
375 
Land use along the Tana River, Kenya - A study with small format 
aerial photography and microlight aircraft 
R. Beck 
DHV Consulting Engineers, Netherlands 
S. W.Taiti 
Land systems and land use Consultant, Kenya 
D.C.P.Thalen 
Research Institute for Nature Management, Netherlands 
ABSTRACT: 
The study executed in 1984 and 1985 for the Netherlands Ministry of Education and Science, had as one of its 
objectives to monitor land use on the riverine lands along the Lower Tana River in Kenya. Monitoring was 
undertaken with a microlight aircraft equipped with small format cameras. A variety of land utilization types 
was identified and located for the different parts of the floodplains and surrounding lands. These land 
utilizations types are based on the association of land use practices, ethnic identities, ecological entities, 
etc. wich coincide at locations with certain environmental conditions, of which the flooding regime of the 
Tana River is a dominant factor. 
The use of the microlight aircraft proved to be of great value during the surveys. Its use contributed greatly 
to the completeness of the study in the very inaccessible area. 
The photographs were flown over preselected areas, or randomly distributed areas met during the photoflights. 
The photograps were produced in runs with forward and sideward overlap, enabling rotonly stereoscopic analysis, 
but even their use in photoblocks. 
RESUME: 
L'étude exécutée de 1984 à 1985 par le compte du ministère neérlandais del'Education et des a Sciences avait 
comme un des objectifs le monitoring de l'utilisation des francbords du fleuve Tana. Kenya. 
Le monitoring est exécuté avec l'aide d'un avion u.l.m. équipé aves des caméras à petit format. 
Un nombre de spectres d'utilisation des terres étaient identifiés et localisés pour les différentes sections 
des francbords du fleuve et ses environs. Ces spectres d'utilisation des terres sont basés sur les techniques 
et cultures de l'agronomie, l'élevage, les identités éthniques et les entités écologiques. Les spectres 
coïncident sur des locations avec des conditions physiques spécifiques, dans lesquelles le régime d'inondation 
du fleuve Tana est un facteur dominant. 
L'utilisation de l'avion u.l.m. a rendu beaucoup de résultats pour l'étude sur un terrain inaccessible. 
La photographie aérienne est réalisée pour des terrains sélectionnés avant ou pendant les vols. Les photos 
sont produites en photoruns avec un recouvrement partiel, permettant l'analyse stéréroscopique, ou même en 
photoblocks. 
1. Introduction 
1.1 The Tana River Remote Sensing Study 
The Tana River Remote Sensing Study (TRRSS) was exe 
cuted in 1984 and 1985 by DHV Consulting Engineers in 
cooperation with the Delft Hydraulics Laboratory, the 
Institute for Nature Management all from the Nether 
lands together with Landevco from Kenya. 
The study, financed by the Dutch Ministry of Educa 
tion and Science, was carried out in conjunction with 
the Tana River Morphology Study (TRMS) in which the 
same organizations participate and which is carried 
out for the Tana and Athi River Development 
Authority.This TRMS is carried out with the objective 
to analyze the effect of current and future interven 
tions, such as reservoirs for power generation, irri 
gation schemes and bridges on the morphology of the 
river and the riverine lands. 
The TRRSS had the objective to test innovative remote 
sensing methods on certain specific research areas in 
the context of an operational project, the TRMS. 
Apart from this methodological objective, the results 
of the TRRSS are of course of great interest to the 
TRMS. Data collection with respect to the selected 
research areas would involve huge means in terms of 
logistics and manpower when no use would be made of 
remote sensing techniques. 
1.2 Environmental setting 
The Tana River is the largest perennial river in 
Kenya and its most important surface water resource. 
It rises from both Mount Kenya and the Nyandarua 
ranges in Central Kenya and enters the indian Ocean 
between the towns of Lamu and Malindi.The catchment 
area of over 100,000 km2 covers approx. 20% of the 
Kenyan territory. The lower Tana River, the subject 
of the present studies covers the alluvial downstream 
half of the river course (625 km.), as well as the 
riverine lands along the river. These riverine lands 
are in fact floodplains, which start at the beginning 
of the study area and reach to the sea, where the 
Tana Delta covers an area of some 3000 km2. In Figure 
1 the upper part of the study area is presented as 
viewed by Landsat . 
These floodplains consist physiographically of two 
units, the levees and the river basin lands. However, 
the climate and hydrological characteristics as flow 
velocity and frequency and duration of inundations 
result in a totally different landscapes, natural 
vegetation and land use in different parts of the 
floodplains. 
The mean annual rainfall in Tana Delta exceeds 900 
mm, the northern parts of the study area have a semi- 
arid climate with less than 300 mm/year of rainfall 
spread over two rainy seasons. 
Largely under direction of the Tana and Athi Rivers 
Development Authority, the national policy concerning 
the Lower Tana River has changed abruptly in recent 
years, the main reason being concern for Kenya's 
energy and food supply and the realization of the 
irrigation potential of the Lower Tana River where 
200,000 ha of land are regarded as potentially suita-