Late Holocene alluvial sediment dynamics of the Wiesent River catchment (NE-Bavaria, Germany): Insights from high-resolution OSL dating and bayesian age-depth modelling

Floodplains are key geoarchives for reconstructing long-term human–environment interactions, particularly during the Late Holocene when anthropogenic influence increasingly rivalled natural controls on fluvial systems. In Central Europe, centuries of land-use change, deforestation, agriculture and hydrotechnical interventions have fundamentally reshaped river morphology, sediment dynamics and floodplain architecture. This study investigates the Wiesent River catchment in northern Bavaria, Germany, as a representative example of the transition from a predominantly natural to a human-dominated fluvial landscape.

We apply a multi-proxy approach combining sedimentological, geophysical and paleoenvironmental analyses with optically stimulated luminescence (OSL) dating to establish a robust chronological framework for floodplain development. Bayesian age–depth modelling of OSL ages significantly reduces chronological uncertainty and enables the identification of successive phases of sediment accumulation and stratigraphic reorganisation. This improved temporal resolution facilitates comparison between floodplain sedimentation patterns and archaeological and historical evidence for land-use change within broader socio-environmental developments.

The floodplains of the Wiesent River catchment are characterised by laterally extensive and locally thick overbank deposits that record pronounced shifts in sediment dynamics during the Late Holocene. Chronostratigraphic patterns indicate that sediment deposition within the floodplain is not synchronous with documented phases of intensified land use in the catchment. Instead, the results point to pronounced temporal offsets between sediment mobilisation in upland areas and its eventual incorporation into floodplain stratigraphy. These offsets highlight the importance of sediment storage and delayed transfer within the catchment, consistent with a sediment cascade framework in which mobilised material may remain stored in hillslopes, colluvial deposits or tributary systems for extended periods before final floodplain deposition.

The chronostratigraphic record demonstrates that floodplain sedimentation does not directly mirror phases of peak human activity, but rather reflects the cumulative and time-transgressive nature of sediment transfer processes. Comparisons with already studied sub-catchments support the regional relevance of these delayed responses. By integrating high-resolution OSL chronologies with sedimentological evidence, this study provides a nuanced reconstruction of fluvial transformation that emphasises temporal lags and internal system feedbacks.

These findings underline the value of well-constrained chronostratigraphy for interpreting fluvial geoarchives in human-modified landscapes. Understanding the timing and pathways of sediment redistribution is essential for disentangling natural processes from indirect human influence and for placing archaeological and historical land-use signals into their geomorphological and geoarchaeological context.