SURFACE AERATION

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