Chapter 3 – Relief, Physiography and Drainage

Abstract

Kenya's relief stretches from sea level to just over 5000 m at the peak of Mt. Kenya. Combined with its tropical latitudinal location, this relief range creates varied physical environment with characteristics that are almost equatorial sharply contrasting with semi-arid and arid environments. Topography is described as both simple and diverse. Its simplistic form is shown by the fact that the relief can easily be separated into lowlands and uplands while diversity is exemplified by the presence of varied landform types which include Equatorial, Savannah, Aeolian, Glacial, Volcanic and Tectonic. The Kenyan landscape, with its wide variety of forms, is closely linked with such factors as climate, micro-climate, water supply, soils, vegetation and agricultural potential. Some of the sharp contrasts in Kenya’s landscape result from the considerable differences in age of the component landforms. These are now warped and broken by faults in many areas while elsewhere volcanic activity has produced further modifications. Earth movements particularly in late Tertiary, Pleistocene and recent times, have resulted in the formation of the major mountain blocks and Rift Valley systems. These were accompanied by extensive volcanic lava emissions, which cover a significant percentage of the country's land surface. As a consequence of volcanism and earth movements, the drainage has been dislocated, interrupted and modified, and there is hardly a river that has not been affected. Many lakes have been formed in downwarped or downfaulted areas. In coastal regions, the history has been further complicated by Pleistocene changes of sea level. Major physiographic regions seems to be associated with the drainage patterns of the country. A combination of the relief, drainage systems and physiographic regions seem to influence the management and planning of the country’s development strategy. The policy makers must therefore design projects and programs for information gathering, analysis and dissemination on the basis of physical geographic factors as well as the man-made innovative improvements of nature. A superimposition of these attributes through Geographic Information System may show areas that are likely to give the greatest production-increasing effects on the basis of a combination of all the resident attributes.