ESurfD Earth Surface Dynamics Discussions ESurfD Earth Surf. Dynam. Discuss. 2196-6338 Göttingen, Germany 10.5194/esurf-2018-64 Theoretical Interpretation of the Exceptional Sediment Transport of Fine-grained Dispersal Systems Associated with Bedform Categories Zhao Tian https://orcid.org/0000-0002-6532-5944 1 Yu Qian 1 Wang Yunwei 2 Gao Shu 3 Ministry of Education Key Laboratory of Coast and Island Development, Nanjing University, Nanjing 210023, China College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China National Natural Science Foundation of China 41676081, 41676077 2016B00814 03 09 2018 2018 1 14 Copyright: © 2018 Tian Zhao et al. 2018 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://esurf.copernicus.org/preprints/esurf-2018-64/ The full text article is available as a PDF file from https://esurf.copernicus.org/preprints/esurf-2018-64/esurf-2018-64.pdf

<p>Being a widespread source-to-sink sedimentary environment, the fine-grained dispersal system (FGDS) features remarkably high sediment flux, interacting closely with local morphology and ecosystem. Such exceptional transport is believed to be associated with changes in bedform geometry, which further demands theoretical interpretation. Using van Rijn (2007a) bed roughness predictor, we set up a simple numerical model to calculate sediment transport, classify sediment transport behaviors into dune and (mega-)ripple dominant regimes, and discuss the causes of the sediment transport regime shift linked with bedform categories. Both regimes show internally consistent transport behaviors, and the latter, associated with FGDSs, exhibits considerably higher sediment transport rate than the previous. Between lies the coexistence zone, the sediment transport regime shift accompanied by degeneration of dune roughness, which can considerably reinforce sediment transport and is further highlighted under greater water depth. This study can be applied to modeling of sediment transport and morphodynamics.</p>