simulation of armouring process in river bed

abstract the concept of armouring is used to discuss the coarse surface layer in rivers. selective erosion in an alluvial channel reach for which there is no upstream sediment supply can lead to formation of a layer coarser than the under laying material. this phenomenon inhibits sediment transport from the reach.numerical modeling of armouring river bed, provides an approach to simulation of this phenomenon, however, these models are complicated in application. in addition, discretisation errors, affect the solution. herein this paper, an analytical-based model has been developed; it is a simple one layer, 1-d, model to analysis different parameters in development of an armour layer, to predict depth of erosion and bed gradation curve of an armour bed. differential equations describing armouring process, have been solved analytically, for each time step. the time steps are selected small enough to solve the equations analytically, for uniform flow, by avoiding discretisation errors.predicted results are then compared by experimental data and numerical model results. this has shown reasonable validation of the model.