LANDFORM, SOILS AND EROSION IN THE NORTH-EASTERN IRANGI HILLS, KONDOA, TANZANIA

The north eastern Irangi Hills of the Kondoa District, Tanzania are severely affected by soil erosion with consequent land degradation caused by the loss of productive soil, gullying, sand deposition on lower slopes, and rapid siltation of lakes. Major changes in land surface morphology and soil characteristics have drastically altered the pattern of cultivation and settlement. A knowledge of soil and environmental conditions that existed prior to the phase of modern accelerated erosion is fundamental to the accurate assessment of land degradational processes, the extent of soil erosion and sedimentation, and the degree and sustainability of land recovery. This paper integrates the results of recent field-based geomorphological, pedological and sedimentological studies in the Haubi and Mwisanga catchments. Landforms, soil toposequences and recent colluvial and alluvial deposits are described in relation to erosion features, the dynamics of vegetation/land use changes and the development of Lake Haubi. Modification of the pre-existing soil landscape by accelerated erosional and depositional processes is discussed.