Reaeration rate estimation using the lag in dissolved oxygen concentration.

Michael G. Waldon

Abstract: Two new methods are derived for the estimation of the reaeration coefficient in a stream. The first method, termed the ' peak lag method ' (PLM), calculates the reaeration coefficient, K, using the observed time lag between solar noon and the maximum afternoon dissolved oxygen concentration. Computer simulation demonstrates that this technique is less accurate for small values of K or short day length. By using a correction term calculated from the observed time lag and the day length, a second technique, termed the ' modified PLM, ' is developed which has improved accuracy in these situations. These methods require only 3 to 5 hours of monitoring to determine the time of the peak, avoiding the logistical problems associated with monitoring throughout the night. Moreover, the PLM does not require data on stream temperature or light intensity, and requires dissolved oxygen data only during the afternoon around the time of its peak value. The PLM also may provide secondary estimates of the reaeration coefficient to corroborate the estimates of older and more widely accepted techniques.

Journal of Environmental Science and Health Part A--Env. Sci. and Eng., (1985) A20(6):661-79.