Published online by Cambridge University Press: 20 April 2006
A narrow flow passing over an obstacle in a rotating channel is analysed. When the upstream Froude number of the flow approaches unity and the obstacle height is sufficiently small, stationary Kelvin waves may appear in the channel. Under these conditions the usual nonlinear hydraulic theory (e.g. Gill 1977) must be replaced by a nonlinear dispersive theory. When the flow upstream of the obstacle is subcritical, the nonlinear dispersive theory produces three solutions, two of which resemble the solutions of hydraulic theory and a third which contains cnoidal lee waves. Upstream influence due to the obstacle becomes a function of obstacle shape as well as height. The ‘controlled’ solution is distinguished by the presence of a partial solitary wave in the lee of the obstacle.