It has been observed that the pattern of free surface in depth-limited flows in gravel bed rivers changes with the stage and channel geometry. It is hypothesised that these patterns are a reflection of the flow structure within the turbulent flow. This paper will report on the use of a mesh-free numerical approach that can be shown to be capable in simulating the free surface behaviour of a shallow flow over rough bed and was then used to attempt to predict the underlying flow. A numerical model based on the Smoothed Particle Hydrodynamics (SPH) approach has been used, by accounting for the flow turbulence and the description of the free surface. The model has attempted to predict the flow velocity profile and bed shear stress patterns. These results have been compared with careful laboratory measurements under different flow conditions. This comparison has demonstrated that this mesh-less SPH approach can simulate reasonably well the free surface flows over a rough bed with limited flow depth but that there are limitations to the method. In the paper the significance of these limitations is discussed.
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