Erosion and sediment budget across scale: A case study in a catchment of the European loess belt

In many cultivated areas of the loess belt in Northern Europe, loamy soils are particularly sensitive to runoff and erosion. Those processes may not be continuous within a catchment, and runoff and erosion responses to rainfall events differ depending on the study scale at which they are examined. Many of the underlying mechanisms of this scale effect are still unknown and/or not well described. The objective of this paper is to identify and quantify the scale effects on runoff and erosion, from the field scale to the catchment scale in the context of the Austreberthe catchment, located in Normandy, in an agricultural area of the loess belt. Based on extensive information compiled at the hillslope and the catchment scales, the runoff and erosion budgets are compared between both scales, showing a more important decreasing effect for erosion (95%) than for runoff (85%) when moving from the hillslope to the catchment scale. The reduction due to the scale change is linear for runoff but not for erosion, underlining the complexity of erosion processes. Comparison of these budgets between both scales shows a significant effect of the vegetation cover as an important connectivity parameter at the hillslope scale, but not at the catchment scale.