Comparison of the propane-area tracer method and predictive equations for determination of stream-reaeration coefficients on two small streams in Wisconsin
This study was made to identify the best predictive equations for a stream's reaeration-rate coefficient. Reaeration-rate information is needed in dissolvedoxygen modeling work, but an actual tracer measurement is not always possible. The propane-area gas-tracer method and predictive equations were compared for determination of stream-reaeration coefficients (K.2) for reaches of two small streams in Wisconsin. The study was made by the U.S. Geological Survey in cooperation with the Wisconsin Department of Natural Resources. The reaeration-rate coefficients actually measured by the propane-area tracer technique were 14.0 per day and 10.5 per day for two reaches of Honey Creek near Monroe, Wisconsin, with 6.98 per day and 0.98 per day measured at separate reaches on Mill Creek near Marshfield, Wisconsin. Of 20 predictive equations evaluated, the top five ranking equations were as follows: Tsivoglou-Neal with 34 percent mean error, Foree with 34.8 percent, Cadwallader with 45.5 percent, Isaacs-Gaudy with 45.8 percent, and Langbein- Durum with 49 percent.