Water erosion risk assessment in south africa: a proposed methodological framework

Abstract

With the increase in human impacts on the environment, especially in terms of agricultural intensification and climate change, erosion processes need to be assessed and continually monitored. In many countries, but particularly in developing countries such as outh frica, standardized methodological frameworks that deliver comparable results across large areas as a baseline for regional scale monitoring are absent. Due to limitations of scale at which techniques can be applied and erosion processes assessed, this study describes a multi‐process and multi‐scale approach for soil erosion risk assessment under outh frican conditions. The framework includes assessment of sheet‐rill erosion at a national scale based on the principles and components defined in the Universal Soil Loss Equation; gully erosion in a large catchment located in the Eastern Cape Province by integrating 11 important factors into a ; and sediment migration for a research catchment near Wartburg in KwaZulu‐Natal by means of the Soil and Water Assessment Tool. Three hierarchical levels are presented in the framework, illustrating the most feasible erosion assessment techniques and input datasets that are required for application at a regional scale with proper incorporation of the most important erosion contributing factors. The methodological framework is not interpreted as a single assessment technique but rather as an approach that guides the selection of appropriate techniques and datasets according to scale dependency and modelled complexity of the erosion processes.

Key words:

• water erosion
• risk assessment
• methodological framework
• South Africa

Acknowledgements

Thanks to the Agricultural Research Council, Institute for Soil, Climate and Water (ARC‐ISCW) for principal funding and equipment supplied. Managerial support, expert advice and constant encouragement given by Dr H.J. Smith (Programme Manager) are very much appreciated. We acknowledge funding from the National Research Foundation (NRF) through the incentive grants for rated researchers but any opinions expressed are those of the authors and therefore the NRF do not accept any liability for the content of this article. The paper benefited greatly from the critical comments by two referees on an earlier version.

Additional information

Notes on contributors

Jacobus J. Le roux

Paul D. Sumner, Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa 0002

Paul D. Sumner

Jacobus J. Le Roux, Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa 0002 and (current) Agricultural Research Council, Institute for Soil, Climate and Water, Private Bag X79, Pretoria, South Africa 0001

E‐mail: [email protected]