The generation and trapping of solitary waves over topography.

Observations of tidal flow over a sill show that upstream solitary wave generation occurred in conjunction with the downstream movement of a streamline bifurcation over the obstacle crest. Solitary waves appeared upstream of the bifurcation, riding on the surface stratification. Shear flow instabilities on the plunging interface were also evident and may contribute to wave generation through subharmonic interaction. Nonlinear waves generated downstream of an internal control became trapped in the supercritical flow.