Soil Erosion, Land Degradation and Social Transition

Geoecological analysis of a semi-arid tropical region, Kenya

Ed.: Rorke B. Bryan

1994. 248 pages, 48 figures, 34 tables, Catena ISBN 978-3-923381-36-4, US-ISBN 1-59326-235-3, 17x24cm, 680 g
Language: English

(Advances in Geoecology, Volume 27)

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land usesoilwater conservation agroforestry


Synopsis top ↑

During the thirty years since the achievement of independence in many African countries, Kenya has been prominent as an apparent exception to the widespread political instability, social disturbance, environmental degradation, famine and desertification which have afflicted so many parts of the continent.
To a large extent this has been achieved because of the high productivity of fertile soils in the humid highlands which form some 25 per cent of the country. Until very recently this has been sufficient to sustain nearly 80 per cent of the Kenyan population, which still has an annual growth rate near 4 per cent, amongst the highest in the world. Land use pressure in the highlands has become intense leading to subdivision of land into non-viable units, and expansion onto steeply sloping lands of lower fertility and high erosion hazard. The highlands cannot sustain significantly higher population, so accommodation of future population growth must depend on significantly increased utilization of the 75 per cent of the country which is arid or semi-arid.
Past attempts to change land use and sustain increased population in Kenyan drylands have not been very successful and have resulted in serious land degradation, particularly in districts immediately adjacent to the densely populated highlands, such as Machakos, Baringo, Kajaido and Laikipia. Physical and ecological processes in drylands differ fundamentally from these in more humid regions. The productive capacity of drylands can be effectively utilised to accommodate increased population without severe environmental degradation only if land use is based on detailed understanding of environmental processes and constraints. The papers collected in this volume result from research carried out in Baringo District of Kenya to provide basic information essential for land reclamation and development of environmentally and socially appropriate land use practices. Baringo has long been regarded as one of the most severely degraded in Kenya. It was chosen for research because degradation poses an immediate threat to the welfare of the population, and because the district exemplifies within a small area many of the environmental problems which have afflicted the Kenyan drylands and, indeed, most dryland regions in sub-Saharan Africa. Baringo is unusual, however, because there is already a considerable history of scientific research and there is also a strong political will to find appropriate solutions. Past attempts to reverse the cycle of environmental deterioration in Baringo have not been very successful, yet most of the ingredients necessary for implementation of environmentally sustainable land use management now appear to be present. With careful and innovative use of the information now available, Baringo could become a model for effective land management in many dryland regions in Africa.

Table of Contents top ↑

R.B. Bryan
Land degradation and the development of land use policies in a transitional
semi-arid region 1
S. Schnabel
Using botanical evidence for the determination of erosion rates in semi-arid
tropical areas 31
J.L. Kiyiapi
Structure and characteristics of Acacia tortilis woodland on the
Njemps Flats 47
R.B. Bryan
Microcatchment hydrological response and sediment transport under simulated
rainfall on semi-arid hillslopes 71
D.J. Snelder
Productivity of eroded rangelands on the Njemps Flats 97
D.J. Oostwoud Wijdenes & J. Gerits
Runoff and sediment transport on intensively gullied, low-angled slopes
in Baringo District 121
J.J.P. Gerits
The potential for irrigated agriculture on the Njemps Flats 143
MJ. Kamar
Natural use of stone and organic mulches for water conservation and
enhancement of crop yield in semi-arid areas 163
A.C. Yobterik & V.R. Timmer
Nitrogen mineralization of agroforestry tree mulches under saline soil
conditions 181
E.K. Kireger & TJ. Blake
Genetic variation in dry matter production, water use efficiency and survival
under drought in four Acacia species studied in Baringo, Kenya 195
D.J. Oostwoud Wijdenes & R.B. Bryan
Gully Headcuts as sediment sources on the Njemps Flats and initial low-cost
gully control measures 205
R.B. Bryan & S. Schnabel
Estimation of sedimentation rates in the Chemeron reservoir 231