An interesting observation

An interesting observation made by Prof. Iadevaia on 7 Jan 2012 suggests that a disturbance in a moving medium does not result in a change of wavelength as a result of the moving medium but a distortion of the disturbance. The stream used for the experiment is found just above the Sabino Canyon Dam. It is wide and shallow with a constant velocity. The flow is laminar. Anyone have any ideas? Maybe a more controlled experiment would reveal what is happening. A curious result non the less.