Modeling DO Conditions in Streams with Dispersion

The tightening of dissolved oxygen (DO) standards in recent years suggests the employment of an accurate predictive method of the BOD‐DO conditions in streams. An advanced method should account for dispersion, which can be significant under transient loadings and attendant large concentration gradients. Such a numerical algorithm is presented in this paper; it is based on the premise that advection is the dominant but not exclusive transport mechanism. The method is accurate (can resolve steep fronts), efficient, robust, and easy to implement. The proposed model has been validated against exact and perturbation‐derived analytical solutions. It has been shown to perform well under quite severe transient source loadings, conditions in which the error of the classical Streeter‐Phelps model is sizeable.