Late Holocene sediment dynamics in a human-dominated fluvial landscape: The Wiesent River catchment in Bavaria, Germany

Central European floodplains represent dynamic and sensitive socio-environmental hotspots significantly reshaped by human activity, particularly since the Early Middle Ages. This transformation fundamentally changed fluvial morphology, dynamics and sedimentary systems, raising questions about when and to what extent these landscapes can be understood as a ‘Fluvial Anthroposphere’. Our study focuses on the Wiesent River catchment in Northern Bavaria, Germany, as a case study to investigate the transition from naturally controlled to human-dominated floodplain systems.

Utilizing a multi-proxy approach including sedimentological, geophysical and chronostratigraphical analyses, we explore how direct (e.g. hydrotechnical installations) and indirect influences (e.g. catchment-wide soil erosion due to agriculture) have altered the fluvial morphology and sedimentary dynamics of the area. Detailed examination of floodplain architecture reveals thick overbank deposits and shifts in sediment dynamics that serve as proxies for anthropogenic activity. Optically stimulated luminescence (OSL) dating allowing us to link increases in sedimentation rates directly to the intensification of human activities within the catchment.

Sedimentation patterns along the Wiesent River correlate well with the Aufsess River sub-catchment (Fuchs et al. 2010, 2011). OSL ages show elevated sedimentation rates during the Migration Period (375-500 CE) and Early Middle Ages (500-1000 CE). Interestingly, while sedimentation was high, substantial human influence, like deforestation appears more prominent from the High Middle Ages on (1000 CE onwards). This temporal disconnection highlights the inherent time lag in the sediment cascade model, suggesting material eroded during the High Middle Ages may still be moving through the sediment cascade system, yet to be deposited in floodplains.