No abstract

Accelerated gullying of dambos (seasonally waterlogged bottomlands) on commercial farms in Zimbabwe has resulted in legislation curtailing dambo cultivation, even in indigenous farming areas. The transfer of indigenous cultivation to interfluve areas and the resultant concentration of cattle grazing in dambos initiated similar gullying. Facilitated overland flow was perceived to be the cause of gullying both in the case of dambo cultivation and dambo grazing, this overland flow re-excavating what was believed to be fluviatile infill.Geomorphological evidence is assembled to show that dambos are not 'fossil' fluviatile systems, nor is their clay infill alluvial. They are the 'lows' of a landsurface irregularly lowered by differential leaching. The infill forms by precipitation of materials leached from the interfluve profiles and discharged into the dambos. The fluviatile-like configuration of dambos is attributed to integration of sub-clay groundwater movement, resulting from landsurface incision. Accelerated gullying in Zimbabwe is deduced to be caused by breaching of the dambo clay by subsurface water movement. The particular vulnerability of Zimbabwe dambos is attributed to: (1) the watershed situation; (2) shallow weathering and (3) the thinness of the dambo clay. Evidence from Malawi indicates that interfluve deforestation and cultivation of shallow-rooted crops conserve water, raising the groundwater level. Such an increased head of groundwater also appears to have occurred in Zimbabwe; this would strengthen upward discharge in the dambos, promoting gullying. Urgent land and water policy revision is required, allowing restoration of dambo cultivation and reafforestation of interfluves, if dambos are to be conserved and the resources which they offer satisfactorily utilized.

No abstract

"This paper critically evaluates the causes and consequences of changes in population distribution in Zimbabwe during the colonial period and since independence in 1980. Five main aspects of population geography are examined. Firstly...the history of tenure policies is outlined. Secondly, the distribution of the African population as revealed in the 1982 census is described and major changes between the census years of 1962, 1969, and 1982 are discussed. Thirdly, changing patterns of settlement and land use within the peasant farming areas (Communal Lands) are examined in the context of increasing population pressures. Fourthly, trends in the...urbanisation of the African population are described. Fifthly, post-independence development policies directed at effecting changes in the distribution of population are discussed with particular reference to the land resettlement programme."