Oscillations of the Sintone River in Japan

Acoustic flowmeters, like the AFFRA, provide continuous data about velocity, stage and discharge, such revealing the history or the `signature´ of the specific site. Often the data is somewhat confusing, sometimes cluttered with spikes or jumps; those seem to have no correlation with the expectations of the operator. Even negative flow is observed and-according to the flowmeter-water runs up-hill. A system error of the flowmeter is then blamed for the obvious disagreement. The author investigated the fluid dynamics of this artificial channel and discovered that the strange current meter readings were due to oscillatory flow phenomena