Unravelling the history of bar kinematics and channel morphodynamics from braided bar stratigraphy

The fluvial stratigraphic record is an important resource for exploring, understanding, and reconstructing the history of Earths surface environments. The complex feedback between flow hydrodynamics and sediment transport largely controls the evolution of channel beds; by understanding the influence of this feedback in building stratigraphy, we can leverage fluvial deposits for creating detailed paleoenvironmental reconstructions and improving landscape evolution models. While significant efforts have helped make these connections in meandering rivers, the connections between morphodynamics and sedimentary deposits are less understood for braided channels. Observations from satellite imagery and repeat field surveys have documented episodes of bar deformation and reworking in active braided rivers. Similarly, the internal architecture of ancient channel bodies has been qualitatively and quantitatively interpreted to infer channel morphodynamic processes in ancient fluvial systems. Here we aim to connect planview kinematics to stratigraphic preservation of braided river bars. We use the numerical model NAYS2DH to provide context into the processes controlling preservation of bar deposits in channel bodies and investigate the degrees to which the internal features of bar packages record bar kinematics and channel morphodynamic processes observed in steady state braided rivers. We document characteristic facies assemblages, architectures, and preservation dynamics that correspond to instances of channel widening, thread reorganization, and scour migration preserved as trends in bar preservation. We compare these trends to examples from ancient deposits and show how this insight can be used to interpret ancient braided-river deposits. Our results provide important context for establishing an expected or statistical baseline level of stratigraphic variability that results from the internal dynamics of braided rivers which will help geologists differentiate deposits that could have resulted from quasi-steady-state braided river conditions from deposits that reflect highly variable discharge regimes. Finally, these models also help to provide insight into the sensitivity of active fluvial systems to local and reach scale changes in sediment supply and hydrology.