Reconstructing Reach-Scale Sediment Regime Shifts Across Successive Stages of Industrialization

Industrialization has reshaped the availability, transport, and storage of fluvial sediments, with direct consequences for long-term geomorphic development and for ecological and socioeconomic conditions. A central feature of this shift is the transition between supply- and transport-limited states, which influences river channel stability, floodplain functioning, and habitat dynamics. Reconstructing such sediment regime changes before the mid-20^th century is, however, difficult due to sparse or missing data on river geometry, hydraulics, and sediment characteristics.

We propose a probabilistic modeling framework to infer reach-scale tendencies toward supply- or transport-limited behavior across successive phases of industrialization under tight data constraints. The approach links sub-catchment sediment delivery to a reach-scale sediment mass balance, accounting for sediment supply, transport capacity and possible retention.

Sediment delivery to individual sections is estimated with a RUSLE-SDR scheme, incorporating temporal variability through historical land cover reconstructions and by scaling hydrological and climatic inputs based on instrumental and reconstructed discharge and precipitation data. Channel hydraulics and transport capacity are approximated without explicit bathymetry by assigning a planform channel type to each section for each industrialization phase and linking those types to probabilistic distributions of width, depth and roughness drawn from empirical parameter libraries. The present, well-documented river state is used as geometric and hydraulic reference, while historical states are reconstructed according to their map-derived channel type using process-based translation rules.

Uncertainty from incomplete geometry, historical reconstructions, and parameter variability is propagated through Monte Carlo sampling, yielding distributions of sediment transport capacity, export, and retention rather than individual deterministic values. Resulting reach-scale sediment mass balances are evaluated probabilistically to classify reaches based on their likelihood of aggradation, erosion, or near-equilibrium conditions for each industrialization phase.

By emphasizing relative sediment regime tendencies instead of absolute fluxes, this approach enables a systematic comparison of how different phases of industrialization are reflected in sediment dynamics, channel stability, and disturbance regimes of ecological relevance across different river types.