The Use of Tasselled Cap Analysis and Household Interviews Towards Assessment and Monitoring of Land Degradation: A Case Study Within the Wit-Kei Catchment in the Eastern Cape, South Africa

Abstract

Land degradation is a global problem affecting many countries. In South Africa extensive degradation can be related to a history of unjust land policies, which resulted in over-exploitation of the land. According to Hoffman and Todd (Journal of Southern African Studies 26:743-758, 2000) the problem is most severe in the communal districts of the Limpopo Province, Eastern Cape, and Northwest Province. Our study used a combination of GIS and Remote Sensing techniques together with field visits and household interviews to determine the spatial characteristics, history and nature of land degradation in the Wit-Kei catchment, in the Eastern Cape Province, South Africa. Vegetation cover and bare-ground change were selected as land degradation indicators. Using time-series analysis of Landsat images over an 18-year period (1984, 1993, 1996, 2000 and 2002), the rate and nature of change was assessed. Results from the Tasselled Cap Analysis technique showed an unexpected overall vegetation cover increase as well as a bare-ground increase in other parts of the study area. Based on field visits and interviews, the vegetation increase was explained by the presence of the invasive Euryops shrub. Bare-ground increase occurred mainly in former cultivated lands where erosion features in the form of gullies and dongas have become problematic. Landholders commented on the decline in food production over time, increase in dongas, and replacement of grassland by Euryops. The occurrence of erosion features on bare ground and the increase of alien vegetation shown by GIS and Remote Sensing techniques was corroborated by the field and household survey, which added a further dimension to the underlying causes. The study demonstrates the value of using a multidisciplinary approach to obtain a holistic view of degradation, from which better-informed management decisions may be made.