Highest Annual Sediment Yield (T/Ha) In 10 Years

Soil erosion is a serious problem in Southern Africa (Lorentz and Schulze,1995). Rooseboom (1992) estimated that the average annual sediment yield in southern Africa varied between 0.3 and 3.3 t/ha. To date a simple method has not yet been found to estimate sediment yield from a catchment. Complex deterministic models are available to estimate erosion processes and sediment transport. However, these models are limited in their application owing to their reliance on calibration.

The Universal Soil Loss Equation, USLE (Wischmeier and Smith, 1978), is an equation which has received recognition as an empirical method useful for planning and design purposes. This method is the foundation for other empirical equations which is then applied at a catchment scale to estimate sediment yield, such as the daily stormflow event based Modified Universal Soil Loss Equation, MUSLE (Williams, 1975), which has been widely verified world-wide and in South Africa (Kienzle et al., 1997).