Author(s): Adam Kiczko; Adam Krajewski; Pawel Marcinkowski

Linked Author(s):

Keywords: Anastomosing river; Sediment transport; Random walk algorithm; Lagrangian modeling; Pydorado; Narew River

Abstract: Anastomosing rivers represent unique multichannel systems that are increasingly rare in temperate zones due to human-induced degradation. These systems, characterized by interconnected channels and flood basins, are vulnerable to channel disappearance, where minor anabranches degrade into single-channel meandering forms. Sediment transport plays a critical role in this process, influencing channel morphology through unbalanced material distribution between branches. This study explores the application of Lagrangian random walk algorithms, implemented via the pydorado Python library, to model passive particle transport (e.g., suspended sediments) in such systems. By integrating depth -averaged hydraulic simulations with statistical particle tracking, the approach links river geometry to transport dynamics. Applied to the Upper Narew River within Narew National Park (Poland), the study uses field measurements of suspended sediment concentrations and flow velocities to investigate particle sorting and deposition patterns. Preliminary results indicate that the depth-sensitivity parameter θ significantly affects particle routing, with values around 0-0.5 aligning with observed sediment distributions. This method offers a computationally efficient alternative to Eulerian models, enabling predictions of conservation measures' impacts on ecohydraulic processes, including potential extensions to biota transport like fish larvae.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.196

Year: 2026