Couplage de modèles 1D et 2D pour l’étude du transport sédimentaire en rivière et cours d’eau lors des crues
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Date
2021
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university of M'sila
Abstract
This study deals with one-dimensional, two-dimensional hydro-sedimentary numerical modeling and the coupled modeling of the 1D hydro-sedimentary model to a 2D hydrosedimentary model in rivers and streams. First, we show the theoretical basis. Next, the RubarBE, Rubar 20TS and Coupling codes of INRAE-Lyon are described, which are used to perform the 1D, 2D and coupling simulations respectively. The use of explicit numerical schemes permits to treat the cases in which the boundary becomes dry or wet without stability problems.
These codes use mean diameter and standard deviation to represent sediment transport which simplifies the study. They give many results like: the maximum water depths or the limit of a flood, the longitudinal and transverse evolution of the river bed and its floodplain, flow discharge, sediment discharge, velocities, diameters evolution, etc. .
In general, the results of the various modelizations are similar. The coupled model is stable even in the event of generalized overflow on the banks or through the dike breach. For lateral coupling, the coupled model saves computation time compared to a 2D model and provides valuable results concerning the flood characteristics as well as the evolution of the topography of the bed. However, the similar simplified representation of the sediment characteristics in the 1-D and 2-D models, revealed deviations in the case of the upstream / downstream coupling which takes place at a cross section perpendicular to the flow direction, because the assumption of homogeneous velocity and concentration is not valid for estimating sediment transport this time. Further research is needed to be able to define an appropriate sediment distribution for the 2D side of the boundary between the two models.
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Keywords
coupled model, RubarBE, Rubar 20TS, floods, numerical scheme, the transfer coefficient, river morphology, sediment, sediment transport, measurments, bed, plains