On the Range of Validity of the Exner-based Models for Mobile-bed River Flow Simulations

The limits of applicability of sediment transport models based on the Exner equation are studied by means of a systematic eigenvalue analysis and numerical simulations. An accurate and efficient numerical model for sediment transport modelling in variable section prismatic channels is introduced. The limits proposed by the authors in previous work, consisting in a 1% upper bound for the sediment concentration, are confirmed and validated. Above this value, the Exner-based model leads to significant differences with respect to heavy sediment transport models, even if concentration values higher than this threshold arise only locally.