Discontinuities in sediment connectivity controlled by human-environment interaction along the sediment cascade of a mesoscale catchment in Central Germany

In many Central European river catchments changes in long-term sediment dynamics are caused by external driving forces (e.g. human impact, climate change). In addition, the sensitivity of fluvial systems to environmental change is controlled by the catchment’s geomorphic connectivity of individual sediment sinks. In this study, we reconstruct the temporal evolution of different types of sediment reservoirs along the sediment cascade in a mesoscale upland catchment to assess its sensitivity to external changes. The chronological evolution of hillslope and floodplain sediments is based on 79 OSL and 83 C¹⁴ ages. Our results show that deposition of hillslope sediments coincides with the first evidence for human-induced soil erosion triggered by the earliest European farmers, but were decoupled from the river network for more than two millennia when the aggradation of overbank fines started and steadily increased. Therefore, the connectivity between the colluvial and alluvial sediment sinks of the catchment is mainly controlled by the landscape geometry and frequency and magnitude of erosion, transport and deposition processes.