A sediment budget of an intensively cultivated downslope area of the Seine River: The Pays de Caux loess plateaux
Abstract
In many cultivated areas of the loess belt in Northern Europe, loamy soils are particularly sensitive to runoff and erosion. The different erosion processes may not be continuous within a catchment, and runoff and erosion responses to rainfall events differ in function of the spatial scale of observation. Many of the underlying mechanisms of this scale effect are still unknown and/or not well described. In addition to spatial heterogeneities, erosion processes are also varying depending on the temporal resolution of measurements from the effect of the temporal dynamic of successive rainfall events to more seasonal variations either influenced by climate or anthropogenic land use changes. The objective of this study is to identify and quantify the scale effects on runoff and erosion, from the field scale to the regional scale. The first part of this study will consider the effect of the spatial organisation of the landscape, both in terms of connectivity and patchiness. The second part will investigate the relative importance of the different processes that emerge as we move from one scale to another. More specifically we will quantify the different form of sediment transfer from local hillslope laminar flow, to concentrated flows to karst areas or to the river systems and, finally, to regional river export to the sea. These different quantifications will be extrapolated at the regional scale, taking into account of the landscape spatial organisation, to establish a regional sediment budget.