Hydrodynamic modelling of lateral outflow of non-cohesive sediment over a side weir

In the realm of open channel hydraulics, there are several models to account for the lateral outflow of water over side weirs. However, there are no rigorous experimental and analytical methods on the analogous outflow of non-cohesive sediments over side weirs. The common practice in 1D sediment transport models is as follows: the non-cohesive sediment load is divided between the channels according to the water discharge ratio of the branches. This manuscript proposes a new model to address the side-load of non-cohesive particles from a channel based on basic concepts of fluid mechanics including the law of the wall and the conservation of mass. The calculation procedure for implementation of this model for usage by practitioners is presented including a praxis example of sand transport over a side weir. The new method can be implemented in 1D shallow water wave computer packages to avoid using 3D modelling.