Effect of flow conditions on stream reaeration coefficients

Contrary to the findings of previous studies of channel-controlled stream reaches, it was found that, in four reaches of a small stream characterized by a series of pools and riffles, reaeration coefficients decrease with decreasing discharge. In the reach with the most pool-and-riffle development, the measured reaeration coefficient under low-flow conditions was 86 percent less than its value during average-flow conditions. A regression equation was developed which accurately predicted the measured values in the four study reaches. The equation appears to have applicability to other similar pool-and-riffle streams.