SURFACE AERATION

A model is proposed for calculating surface reaeration flux for dissol ved oxygen (DO) calculations in a river. It is based on a two-film app roach, where film thickness is estimated from turbulent length scale a nd diffusivity considerations, and requires only one calibration coeff icient. Equivalent values of the reaeration coefficient are calculated and shown to compare well with previous empirical or semiempirical mo dels tested against extensive data sets under well-mixed (vertically) conditions. The present approach allows a simple calculation of surfac e oxygen flux and provides a means of modeling DO in a density-stratif ied river, in which many previous formulations are inadequate since th ey are based on vertically averaged conditions.