Abstract
In recent decades, a variety of morphodynamic model systems have been developed to improve our understanding of sediment transport and the resulting changes in riverbed topography. Despite progress in the description of physical processes, the degree of accuracy of morphodynamic model results remains difficult to assess and are also less than for hydrodynamics alone. In this paper, three different 2D morphodynamic systems have been applied to simulate a complex hydrodynamic and morphodynamic situation. These model systems were validated using data of sediment sorting and bed deformation conducted in a 180° channel bend under unsteady-flow conditions. The calculations obtained by each modeling system were compared with the available observed data. The simulated results showed that all applied morphodynamic models could precisely calculate the bed level changes and the areas of deposition and scour. However, the models are not efficient enough to predict the distribution of the mean grain size in the channel bend.
Highlights
Rivers are present in nature in a variety of forms, such as straight, sinuous, meandering, and braided, because of interacting processes among water flow, sediment transport, and vegetation.Modeling of hydro-morphodynamics, known as river morphodynamics, is vital to understand how the mentioned interacting processes work
Several formulations for the same process exist. Most of these formulations employ an empirical relation for the equilibrium transport rate, which corresponds to the transport capacity of the flow, i.e., the bed material load discharge is equal to the sediment transport capacity of the flow
Sediment transport equations are equilibrium relationships based upon laboratory and field data collected under uniform flow conditions in shallow water bodies
Summary
Rivers are present in nature in a variety of forms, such as straight, sinuous, meandering, and braided, because of interacting processes among water flow, sediment transport, and vegetation. Schemes, flux-corrected transport scheme, monotonic upstream-centered schemes for conservation laws (MUSCL) based on [8], and the piecewise parabolic method (PPM) Another important class of high-resolution schemes belongs to the approximate Riemann solvers from previous work [9]. ECOMSed [22], Mike-21 [23], Delft3D [24], ROMS [25], FAST3D (developed at the Institute of Hydromechanics, University of Karlsruhe, Germany), HYDRO-FT, TELEMAC-MASCARET, and BASEMENT are some examples of hydro-morphodynamic modeling systems, which generally include different flow modules (from 1D to 3D), a wave propagation model, and a sediment transport model, including bed-load and suspended load. In order to evaluate the efficiency and accuracy of each model system, the simulation results are compared with measured bed topography and sediment sorting in the channel bend obtained in the laboratory in a previous study [28]
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