Geomorphic thresholds and the characteristics of Vetiver grass in a mined landscape in eastern Pretoria - South Africa

Adjorlolo, Zeria
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The use of Vetiver grass (Vetiveria zizanioides), namely the Vetiver System (VS) for mine tailing slope stabilization and erosion control is common practice. It is therefore important to understand the anthropogenic topographical signatures which affect the application of VS for revegetation of landscapes with mine tailings and hillslopes. This research focused on the assessment of slope features in order to understand their influence on VS application at a diamond mine located in the Cullinan area, Pretoria-East, South Africa. The specific objectives were to (i) assess a fusion approach to deriving Digital Elevation Model (DEM) data and then generate some derivates of slope including steepness, curvatures and surface exposure indices; and (ii) assess capacity of high-resolution remote sensing data for estimation of above ground vegetation cover on mine tailings and hill-slopes under to the Vetiver system. The data processing followed analytical capabilities in Geographic Information Systems (GIS). Results show that SPOT-6 derived NDVI was effective in predicting above ground vegetation cover (%) with an R2 of 0.72 and a Root Mean Square Error (RMSE) of 8.87%. The assessment of topographic influences on VS application for revegetation highlighted the significant contribution of data fusion within GIS. This enables derivation of accurate DEM for characterizing slope features and vegetation cover in the study area. This research can be used as a basis for future work (i) evaluating data fusion techniques for generation of accurate DEM; and (ii) assessing topographic influences on VS in revegetation, erosion control, or soil remediation activities. The methodological approaches in this research affirm the capabilities of GIS and remote sensing techniques for generating accurate but low-cost data which eliminates the need for extensive fieldwork. Overall, this research should be of interest to environmental experts planning erosion control interventions in anthropogenic topographical landscapes with mine tailing signatures.
A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science at the School of Geography, Archaeology & Environmental Studies.
Adjorlolo, Zeria. (2019). Geomorphic thresholds and the characteristics of Vetiver grass in a mined landscape in eastern Pretoria - South Africa. University of the Witwatersrand,