A hydro-morphodynamic model integrating extended sediment particle size distribution and flocculation processes for better simulating hydro-sedimentary fluxes

Many studies focusing on suspended sediment transport modelling in river systems only consider one class of sediment grain size. Rather recently, the SISYPHE sediment transport model has integrated sand-mud mixture transport processes using two classes of sediment. However, this new modelling framework still suffers from limitations, and increasing the number of sediment classes would arguably improve sediment transport and therefore riverbed evolution simulations. Moreover, current sediment transport models do not simulate sediment particle aggregation and disaggregation processes while these can play an important role in sediment transport. Integrating these new concepts would then contribute to significant improvements to river bed morphodynamics and sediment transport modelling. In this study, we further develop the SISYPHE model by extending the sediment particle size distribution to ten classes and integrating flocculation processes (coupling with the flocculation FLOCMOD model). The preliminary results we present in this paper are based on a large-scale flood event, which occurred in river Orne, north-eastern France. We clearly show that the proposed developments of SYSIPHE improves qualitatively and quantitatively the predictions of sediment transport and riverbed morphodynamics