ABSTRACT
This study examined the morphological behavior of the bed in an open channel flow with vegetation effects by means of a depth-averaged two-dimensional numerical model. We simulated the river morphodynamics under various vegetation densities and angles of repose in order to examine whether the aforementioned relations between the angle of repose and characteristics of river morphology can be reproduced numerically. We employed a computational model with depth-averaged two-dimensional shallow flow equations and an equilibrium bedload sediment transport model. In order to take into account the effect of angle of repose, a bank failure model is also incorporated. The numerical results showed that general characteristics of the bed morphology simulated by the present model are in compatible with the features pointed out in the previous papers. Namely, if the angle of repose is larger or smaller, the river becomes meandered or braided, respectively. The present computational results are also compared with the theoretical results by Muller. The agreements between the computations and the theory were generally good. The present computations, not only support the previous empirical and theoretical results on river morphology depending on angle of repose, but also show that the present computational model is a powerful tool to predict river morphology under effects of vegetation.
