Soil Surface Roughness as the Result of Aggregate Size Distribution 2. Report: Change in aggregate size classes caused by erosive rainfalls

The change of aggregate size classes caused by rainfall was examined using six different silty soils. The surface elevation profile lines were measured with a non-contact laser scanner with a measurement resolution of 0.1 mm. The profile length ratio RZ and, based on the Fourier-analysis of the elevation profile line, the partial roughness were determined. The results demonstrate that in contrast to the profile length ratio RZ, the evaluation of partial roughness is an adequate method to determine the proportion of aggregate size fractions on total surface roughness. Furthermore, the results show that - independent of the soil texture and history - the smallest aggregate size classes are the most labile fractions. These small and labile aggregate size fractions are involved in the soil erosion process, especially in surface sealing. The extent of surface sealing, however, is influenced by soil texture, too.