Controls on a scale explicit analysis of sheet erosion

2012

Article référencé dans le Web of Science WOS:000305511100004

Oakes E. G. M., Hughes J. C., Jewitt G. P. W., Lorentz S. A., Chaplot Vincent

Earth Surface Processes and Landforms, 2012, 37 (8), p. 847-854 ISSN 0197-9337

Although the impact of sheet erosion on the evolution of soils, soil properties and associated ecosystem services across landscapes is undisputed, there are still large uncertainties in the estimation of sheet erosion, as the results obtained are highly scale dependent. Consequently, there is a need to develop a scale-explicit understanding of sediment erosion yields, from microplot to hillslope through to plot, to surmount actual erosion modelling flaws and to improve guidance for erosion mitigation. The main objective of this study was to compare sediment yields from small and large plots installed under different environmental conditions and to interpret these results in terms of the main mechanisms and controlling factors of sheet erosion. Fifteen 1x1m(2) and ten 2x5m(2) plots were installed on a hillslope in the foothills of the Drakensberg, South Africa. Data of runoff, sediment concentration (SC), soil loss (SL) and rainfall characteristics obtained during the 2009-2010 rainy season at the two spatial scales and from different soils, vegetation cover, geology and topographic conditions were used to identify the main controlling factors of sheet erosion. Scale ratios for SC and SL were subsequently calculated to assess the level of contribution of rain-impacted flow (RIF) to overall sheet erosion. The average runoff rate (n?=?17 events) ranged between 4.9 +/- 0.4?L?m-2 on 1?m2 and 5.4 +/- 0.6?L?m2 on 10?m2, which did not correspond to significant differences at P?