Longitudinal profiles of rivers with a composite cross-section

Abstract

In one-dimensional river modelling it is common to schematise the cross-section into a rectangular cross-section with a constant width. If a quasi-steady flow is assumed, the equilibrium longitudinal profile is known and unique: the bottom slope is constant and equals the water surface slope. However, numerical calculations at DELFT HYDRAULICS suggest that for rivers with a composite cross-section more equilibrium longitudinal profiles can exist. In addition, it appears that a stable curved equilibrium can exist. As an example, a river with floodplains can be mentioned to have a composite crosssection. This report contains a study on the equilibrium longitudinal profiles of rivers with a composite cross-section. In order to calculate these profiles, and their stability, three different models are applied to a schematised river. Calculations are done both analytically and numerically, and all results are visualized in phase diagrams.Hydraulic EngineeringCivil Engineering and Geoscience