Perspectives on prehistoric and recent gullying in Central Zimbabwe

Abstract

Gullies up to 5 m deep are developed on sodic soils near St. Michael's Mission, central Zimbabwe, A preliminary study was undertaken to reconstruct the nature and timing of past gullying, and to determine the main factors affecting gully growth during the last 50 years. The gullies are formed in colluvium, with interbedded humic layers and stonelines containing stone artefacts, reflecting cycles of gully entrenchment, sheetwash and pedogenesis which occurred during the Late Quaternary. Significantly, historical and present day gully growth appears to be both more extensive and intensive than at any earlier period in the Late Quaternary. Recent gully growth appears to be a function of complex interaction of physical and anthropogenic factors. Attempts to arrest gully headward extension are discussed. It is argued that long and medium term perspectives on gully erosion, combined with present day observations, offer a more balanced view of the soil erosion problem.