Surface wash on a low-angled slope near Bloemfontein
Le Roux, J.S.; Roos, Z.N.
South African Geographical Journal 64(2): 114-124
Surface wash was measured for three consecutive years on a fairly low-angled slope by means of 6 pairs of wash-traps. The erosion rate was found to be more or less constant over the whole slope. This implies that, for the period under observation, the slope retreated parallel to itself. Multiple regression analysis of erosion (dependent variable), rainfall, rainfall intensity and the product of rainfall and rainfall intensity indicated that the only truly significant variable was the product of rainfall and rainfall intensity. The three variables together accounted for 58 percent of the variance in erosion. The rate of soil loss calculated from the wash-trap data for 37 runoff events was 46 g m-2 per year or, calculated as ground lowering, 18 mm 1000 yr-1 at rock density, or 34 mm 1000 yr-1 at soil density.