Time Domain Reflectometry is an inexpensive, highly robust, and accurate tool for measuring the air content of turbulent air:water mixtures in natural settings.

The air contents of natural hydraulic jumps on the American River vary dramatically through time over the full range possible (0-100%), but typically average ~25%.

Small hydraulic jumps have significantly lower air contents than large air hydraulic jumps, consistent with the understanding that a threshold velocity is needed in order to entrain air into the water and turbulently mix it up producing bubbles.

Background - Objectives - Air Content Measurements - Conclusions - Lab Methods - Single Phase Test Results - Air-Water Mixture Calibrations - Turbulent Air-Water Mixture Time Series
Field Methods - Field Site - Field Results


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