Surface Roughness Related Processes of Runoff and Soil Loss: A Flume Study

Abstract

Soil surface roughness greatly affects surface sealing and runoff generation, yet little information is available about the effect of roughness on the spatial distribution of runoff and on flow concentration. This study tested the hypothesis that runoff distribution and flow concentration differ with roughness and affect the amount of soil loss. Sequences of four rainstorms of constant rainfall amount but decreasing intensity (60, 45, 30, and 15 mm h−1) were applied to the Ap horizon material of a loess soil (Glossic Fragiudalf) packed into a 0.6 by 3.7 m flume. Rough, medium, and smooth soil surfaces were studied at 17, 8, and 2% slope steepness. Surface roughness and flow pathways were visualized with digital elevation maps obtained from laser microrelief measurements. On the smooth surfaces, runoff was uniformly distributed during the first two rainstorms and soil losses were 0.23, 0.07, and 0.12 kg m−2 for the first and 2.26, 0.35, and 0.2 kg m−2 for the second storm at 17, 8, and 2% slope steepness, respectively. On the rough and medium surfaces, flow concentrated in pathways between clods and soil losses were up to eight and three times that on the smooth surfaces during the first and second storms, respectively. During the last two storms, flow concentrated also on the smooth surfaces and soil losses were similar for the three initially different surface configurations. Surface roughness effects on runoff amount were minor, but roughness affected the spatial distribution of runoff, thereby affecting the amount of soil loss.

Modeling fine‐scale soil surface structure using geostatistics

“…Such processes are important in influencing surface flow routing and hydrological connectivity [Darboux et al, 2001;Helming et al, 1998;Kamphorst et al, 2000]. Runoff generation from soils is a spatially distributed process where surface morphology, at a range of spatial scales, controls the surface flow routing [Darboux et al, 2001].…”

A multifractal approach to characterize cumulative rainfall and tillage effects on soil surface micro-topography and to predict depression storage

“…This effect is more evident in soils where a surface seal develops. However, a higher surface roughness and, therefore, larger depression storage does not always reduce runoff and/or erosive soil losses (Helming et al, 1998;Darboux and Huang, 2005).…”

Quantification of tillage, plant cover, and cumulative rainfall effects on soil surface microrelief by statistical, geostatistical and fractal indices

“…Therefore, the term "random" only describes non-orderly distribution of structural unities on the soil surfaces and should not be misleading, since random roughness is spatially correlated at short distances (Linden and van Doren, 1986;Huang and Bradford, 1992;Helming et al, 1998;Eltz and Norton, 1997;Miranda, 2000;Zribi et al, 2000;Vidal Vázquez et al, 2005. This correlation seems to be a usual property of soil surface random roughness irrespective of soil type and tillage condition.…”