Holocene sediment fluxes in a fragile loess landscape (Saxony, Germany)

Abstract

The loess region of the Central Saxon Hill Country is characterized by a relief of gently rolling hills, whose most distinctive landscape elements are well-defined shallow valleys, called dells. The aim of this research is to gather morphodynamic information on the dells in a qualitative and quantitative way by means of high-resolution field mapping and laboratory-based analyses. The intensity of sediment shifting has been modelled via sediment budgeting on a small catchment scale. Research objectives are to determine the character and magnitude of geomorphic processes for a Holocene time frame. Concerning the absence of currently obtainable dating, this study represents a reflection, which summarises all sediment shifting related to anthropogenic land use during the Holocene. As a specific parameter in terms of landscape development, the relief is considered to be strongly associated with varying process intensities. Agrarian land use of the loess region since the late Neolithic has resulted in severe soil erosion. Lower middle slope positions are the apparent spots were soil erosion processes take place in terms of rill erosion. A detailed survey of three dells provided a very heterogeneous pattern of the relocation of soil material. Dell 1 (Zehren) shows medial Holocene soil profile truncation of 1090 mm. In contrast, dell 3 (Löbschütz) shows soil loss of around 660 mm. All systems have similarly high slope gradients up to 12°. Actually, the deepening of the dell´s depth contours and therewith the extent of erosive slope lengths is varying. Thus, a higher longitudinal decline of the valley floors and a more intensive incision, lead to enlarged erosive slope lengths, which causes increasing sediment transport. Hence, land-use patterns trigger the process of material displacement, whereas relief modifies the intensity of geomorphic processes.