Fundamental features of transitional distributions of velocity and shear in a run-up wave have been experimentally identified in this paper. In the run-up front, vertically uniform shore-ward velocity is predominant, while typical free-surface shearing flow with a bottom boundary layer is formed behind the front. Depending on local surface gradients and fluid acceleration, reverse streaming occurs within the boundary layer despite the shore-ward flow still dominates above the layer. In the later stage, another shear layer has also been formed beneath the surface.
