Two-dimensional finite element river morphology model

We report the development and application of a river morphology model based on the two-dimensional depth-averaged hydrodynamic model River2D. This new movable bed version of River2D was applied to simulate the bed elevation changes in four experiments: bed aggradation due to sediment overload, bed degradation by sediment supply shut-off, knickpoint migration, and bar formation in a variable-width channel. Some conditions in these experiments involved quick changes in the upstream boundary conditions, rapidly varied flow, supercritical flow, hydraulic jumps, and secondary flows. The results of the model agreed well with measured data. Notable features of the model are the use of a flexible unstructured mesh based on triangular finite elements to provide higher spatial resolution in areas of interest and transcritical flow capabilities to simulate supercritical flow and hydraulic jumps over movable beds. Key words: numerical modeling, rivers, scour, sedimentation, two-dimensional, finite elements.