SOIL EROSION IN THE CENTRAL MIDLANDS OF KWAZULU-NATAL: A COMPARATIVE STUDY

ABSTRACT

In 1992 the Water Research Commission developed an erodibility index map for Southern Africa. This map considers a single factor viz., soil erodibility in estimating potential soil erosion. There are, however, several other known factors that influence soil erosion. The aim of this study was to assess whether the erodibility index map of Southern Africa, representing potential soil erosion, compares favourably with actual soil erosion. A sub-catchment with an areal extent of 1340km² situated within the Thukela and the Mgeni catchments was chosen to execute this investigation. The method of data extraction for the investigation involved stereoscopic interpretation of aerial photographs. The data extracted from the photographs were used to produce soil erosion maps. These maps were then compared to that of the erodibility map. The technique employed to execute the comparison was the chi² test. The comparison between actual and potential soil erosion indicates that a discrepancy exists between the two. The discrepancy leads to the conclusion that the erodibility index map of Southern Africa does not represent actual erosion on the ground, at least with regard to the study area.