Changing sediment yield and sediment dynamics in the karoo uplands, south africa; post-european impacts
Land Degradation and Development
School of Science and Technology, University of Northampton, Newton Building, Northampton NN2 6JD, United Kingdom; Department of Geography, Rhodes University, Grahamstown, 6140, South Africa; Environmental Change Institute, Oxford University Centre for the Environment, South Parks Road, Oxford, OX1 3QY, United Kingdom; Department of Environmental and Geographical Science, University of Cape Town, Rondebosch, 7700, South Africa; Department of Geography and the Environment, University of Aberdeen, AB24 3UF, United Kingdom
We provide an overview of published results and a significant body of new data from an ongoing research programme designed to reconstruct sediment yields and sources in small (<60km2) catchments in the Eastern Cape, South Africa over the last 150years. Our analysis of four catchments has determined that sediment yield increased significantly in the latter half of the 20th century but that the exact timing of these increases was different in each of the four catchments. In two high altitude locations, sediment yield increases were not associated with a significant change in sediment source although, in one case, areas of former cultivation appear to have made a slightly greater contribution since the 1960s. In a third catchment, increases in sediment yield appear to have been driven by the development of badlands and by an increase in connectivity between the badlands and the main channel network in the 1960s. In the fourth catchment, increased connectivity between the main catchment and dam occurred as a result of the construction of a causeway to carry a main road and by the construction of culverts beneath the road. Occasional changes in sediment source have also been identified in the sedimentary record, but these were not linked directly to road construction. Research to date shows the complexity of sediment delivery in these semi-arid catchment systems and emphasises the need to combine sediment yield with source ascription to better understand the dynamics of these systems. © 2012 John Wiley & Sons, Ltd.
Karoo; Land-use change; Sediment sources; Sediment yields; Weather and climate; Digital storage; Dynamics; Landforms; Roads and streets; Runoff; Sedimentology; Sediments; Catchments; badlands; catchment; cultivation; land use change; road; sediment yield; upland region; Eastern Cape; Karoo; South Africa