Fully coupled modelling of non-uniform sediment transport in sewer systems

Flushing is considered as a cost-effective technique for mitigating sediments and constraining environmental problems in sewer systems. Previous mathematical models are almost exclusively based upon simplified governing equations and weak sediment transport assumptions, of which the applicability remains to be theoretically justified. Here a fully coupled one-dimensional model is presented for non-uniform sediment transport in sewer systems, as adapted from recently established shallow water hydro-sediment-morphodynamic models for fluvial processes. The present model is tested for an experimental flushing case in the Des Coteaux catchment system of Paris city. The computational results are compared with measured data, and satisfactory agreements are acquired. It is revealed that the adaptation of bedload sediments to capacity regime can be fulfilled quickly, while the adaptation of suspended sediment transport to capacity regime requires a relatively long time and space, thereby underpinning and warranting the non-capacity modelling paradigm for sewer systems.