1D morphodynamic modelling using a simplified grain size description

B. Camenen (1) , C. Beraud (2) , Jérôme Le Coz (1) , André Paquier (1)

1 RiverLy - Fonctionnement des hydrosystèmes
2 Lowestoft Laboratory

This paper introduces an 1D numerical code RubarBE for hydraulic and mobile-bed simulations. The code's ability to reproduce the downstream fining of a gravel-sand mixture in response to bed aggradation is tested against laboratory experiments. Unlike in most numerical models, grain size distribution in each sediment layer is not represented using a multi-class model, but using the median diameter d50 and a sorting coefficient σ. The comparison of numerical results with experimental data shows that the adaptation length La, classically used for non-equilibrium sediment transport, is an essential parameter of the model to accurately reproduce the evolution of the deposit front. Empirical laws for adjustments of d50 and σ are proposed to reproduce sediment sorting through two grain-size related adaptation lengths (Ld, Lσ ). They are scaled by the length of the reach in morphological equilibrium, which is a useful result for field applications.

Mots clés: sediment; one-dimensional model; hydraulics

Mots clés: MODELE UNIDIMENSIONNEL; HYDRAULIQUE

Domaines: Sciences de l'environnement

B. Camenen, C. Beraud, Jérôme Le Coz, André Paquier. 1D morphodynamic modelling using a simplified grain size description. Journal of Hydraulic Research, 2018, 56 (2), pp.168-180. ⟨10.1080/00221686.2017.1312575⟩. ⟨hal-01945349⟩